1. X pure material is solid at room temperature. if the substance is heated to 230 C melted gradually. if it is then cooled to room temperature, the liquid can not be frozen.
a. that x may be from an element or compound. explain it!
b. Is it a chemical change occurs? if so could be said to undergo change endotherm, based on the information provided?
c.can said that the liquid is an element, based on the information provided Answer:
a.X
is the element (sulfur), because at temperatures below 95.5 C he would
stabilyang dinamakn rombik sulfur was the temperature is above him akn
kristaldan transformed into monoclinic form, so that does not freeze at
room temperature is monoclinic sulfur because he akn stable and frozen at temperatures above 95.5 C while rombik not.
b. Chemical
changes that occur are changes in the endothermic reaction because the
element X to convert solid to liquid heat transfer resulting from the
environment to the system (heat absorbed by the system from its
environment), a marked drop in the ambient temperature around the
system.
c. Yes,
because the fluid including elements At room temperature (25 C)
elements can be solid, liquid or gas, and the elements of X changes as
heated
2. When
the candle that weighs 10 g burned in oxygen, carbon dioxide and water
vapor formed by the combustion of more than 10 g weight. This was the case in accordance with the law of conservation of mass. Explain!
Answer:because
the wax that has mass of 10 grams when it reacts with oxygen to form
water and carbon dioxide, the mass of wax will react with oxygen mass
and it will add weight to the results obtained are water and oxygen.
3. When carbon burns under a limited amount of oxygen, it forms two gaseous compounds. Suggest ways to diffrerentiate two compounds with one another
Answer:to
distinguish compounds resulting from one compound to another compound,
is to look at the properties of chemical, odor, and color can also
denagn if distinguish compounds resulting from the burning of carbon
with oxygen was also reacting carbon monksida bias (CO) with lime water (
Ca
(OH) 2), and carbon dioxide (CO2) with lime water, the carbon monoxide
can not react, while the carbon dioxide will memebentuk calcium
carbonate (CaCO3)
4. After
mendeev preparing the periodic table, he concluded that the atomic
weights of some elements was the wrong decision, and this conclusion
appears to be true. How mendeelev able to predict some of the atomic weights is wrong? why his predictions are not always right. Explain!
Answer:In
1869 a Russian scholar named Dmitri Ivanovich Mendeleev, based on
observations of 63 elements known at the time, concluded that the
properties of elements are a periodic function of the relative atomic
mass. That
is, if the elements are arranged according to their relative atomic
mass increases, the specific properties will be repeated periodically. Mendeleev placed elements that have similar properties in vertical columns called class. Row-column
horizontal line element that increases the relative atomic mass, called
the Mendeleev periodic period in 1872 published a list displayed on the
table.
As can be seen in the picture above, Mendeleev mengkosongkan some places. This is done to establish the nature of equality in the classroom. For
example, placing Mendelev Ti (Ar = 48) in group IV and group III were
left empty because Ti is more similar to C and Si, compared with B and
Al. Mendeleev predicted the properties of elements that have not known it. Estimates
are based on the nature of the other elements that have been
recognized, which is adjacent either horizontally or upright. If these elements are predicted to have been found, is in accordance with the predictions Mendeleev. One example is germanium (Ge), which was found in 1886, which Mendeleev called ekasilikon.The weakness of this theory is still contained elements of a larger mass that lies in front of a smaller mass elements. Co: Tellurium (te) = 128 in kiriIodin (I) = 127. this is because the elements have properties kemirpan placed in one class. The weakness of this theory is the atomic mass correction. Previous atomic mass. In previous atomic mass = 76-113. besides Be, 13.5 to 9. N 120-240.The advantage is forecasting a new element predictable elements and their properties.
5. When the mercury chloride solution is added a solution of silver nitrate, a white solid forms. Identification of a white solid and write a balanced equation for the reaction that occurs
Answer:HgCl2 + 2AgNO3 ---> Hg (NO3) 2 + 2AgCl
The resulting white powder is (AgCl)
Rabu, 14 November 2012
Selasa, 30 Oktober 2012
atomic structure and quantum numbers
The
structure of an atom is the basic unit of matter consisting of a
nucleus and its negatively charged electron cloud surrounding it. [1]
The nucleus contains a mix of positively charged protons and
electrically neutral neutrons (except in Hydrogen-1 which has no
neutrons). The electrons in an atom bound to the nucleus by the electromagnetic force. Similarly, a collection of atoms can bind to each other to form a molecule. Atoms
containing the number of protons and electrons of the same neutral,
while containing the number of protons and electrons of different
positive or negative and is ion. Atoms are grouped based on the number of protons and neutrons in the atomic nucleus. The
number of protons in an atom determines the chemical element the atom,
and the number of neutrons determine the isotope of the element.The term atom comes from the Greek, which means it can not be cut or something that can not be divided again. The
concept of the atom as a component that can not be divided again was
first proposed by the philosophers of India and Greece. In
the 17th century and into the 18th, the chemists laid the foundations
of this idea by showing that certain substances can not be broken down
further using chemical methods. During
the late nineteenth century and early twentieth century, physicists
have managed to find the structure and subatomic components inside the
atom, to prove that the 'atom' is not never be divided again. [1] The
principles of quantum mechanics are used The physicists then successfully model the atom. [1]Relative to daily observations, the atoms are very small objects with masses as minor anyway. Atoms can only be monitored using special equipment such as tunneling microscope Microscopy. More than 99.9% of the mass of the atom is concentrated in the nucleus, the proton and neutron are almost the same mass. Each element has at least one isotope with unstable nuclei that can undergo radioactive decay. This can lead to transmutation that changes the number of protons and neutrons in the nucleus. Electrons
are bound to the atom contains a number of energy cedar, or orbital,
which is stable and can undergo transitions between these cedar by
absorbing or emitting photons that match the energy difference between
the levels. The electrons in the atom determines the chemical properties of an element and affect the magnetic properties of the atom.
Ban Pauli principle is the principle of quantum mechanics formulated by Austrian physicist Wolfgang Pauli in 1925. In its simplest form for electrons in a single atom, this rule states that no two electrons having the same quantum numbers. So if n, l, and ml both electrons are all the same, ms must be different, so that the two electrons have opposite spin. More generally, there is no two identical fermions (particles with fractional spin) may occupy the same quantum state simultaneously.
Periodic systems and rule Aufbau; Block s, p, d, and fThe link between the periodic table with electron configuration (Aufbau principle) can be seen as in the picture below.We can see that the Aufbau principle moves from left to right throughout the period, and then increased to the next period. Each period begins with a sub-shell and closed subshell ns np (n = number of periods).1s 2s 2p 3s, 3p 4s, 3d, 4p 5s, 4d, 5p 6s, 4f, 5d, 6p 7s, 5f, 6dPeriod 1 2 3 4 5 6 7Based on the type of electron orbitals occupied by the last elements in the periodic system is divided into blocks of s, p-block, d-block, and the block f.a. Block s: class IA and IIAS-block metal classified as active, except H and He. H classified as non-metallic, while the noble gases He classified.b. Block p: group IIIA to VIIIAP-block elements called representative because there are all kinds of metals, non-metals, and metalloids.c. Block D: group IIIB to IIBBlock D is also called transition elements, all belonging to the metal.d. Block f: lanthanides and actinides
1. The principal quantum number (n): realizing the trajectory of electrons in atoms.n has a price of 1, 2, 3, .....- N = 1 corresponds to the K shell- N = 2 correspond to the L shell- N = 3 corresponds to the skin M- And so onEach skin or any number of energy levels occupied by electrons. The number of electrons that can occupy maksimmm energy levels must satisfy the Pauli formula = 2N2.Example:skin-to-4 (n = 4) can be occupied by a maximum = 2 x 42 electrons = 32 electrons2. Azimuthal quantum number (l): indicate sub skin where the electron also shows sub skin which is a constituent of skin.Azimuthal quantum number have prices from 0 to (n-1).n = 1; l = 0; corresponding K shelln = 2, l = 0, 1; corresponding L shelln = 3; l = 0, 1, 2; appropriate skin Mn = 4; l = 0, 1, 2, 3; appropriate skin Nand so onSub leather prices vary is given a special name:l = 0; fit leather sub s (s = sharp)l = 1; fit leather sub p (p = principle)l = 2; fit leather sub d (d = diffuse)l = 3; fit leather sub f (f = fundamental)Magnetic quantum number (m): realizing the presence of one or several levels of energy in a sub shell. Magnetic quantum number (m) has a price (-l) to price (+ l).For:l = 0 (sub leather s), price m = 0 (having 1 orbital)l = 1 (p sub shell), price m = -1, O, +1 (have 3 orbitals)l = 2 (sub skin d), price m = -2, -1, O, +1, +2 (have 5 orbitals)l = 3 (sub kwit f), price m = -3, -2, O, +1, +2, +3 (has 7 orbitals)4. Spin quantum number (s): indicates the direction of rotation of the electron on its axis.In one orbital, maximum of 2 electrons can circulate and the two electron spins through the axis in the opposite direction, and each is priced spin +1 / 2 or -1 / 2.
Question : according to the theory of quantum mechanics, electrons in the atom does not have a definite orbit, why?
Ban Pauli principle is the principle of quantum mechanics formulated by Austrian physicist Wolfgang Pauli in 1925. In its simplest form for electrons in a single atom, this rule states that no two electrons having the same quantum numbers. So if n, l, and ml both electrons are all the same, ms must be different, so that the two electrons have opposite spin. More generally, there is no two identical fermions (particles with fractional spin) may occupy the same quantum state simultaneously.
Periodic systems and rule Aufbau; Block s, p, d, and fThe link between the periodic table with electron configuration (Aufbau principle) can be seen as in the picture below.We can see that the Aufbau principle moves from left to right throughout the period, and then increased to the next period. Each period begins with a sub-shell and closed subshell ns np (n = number of periods).1s 2s 2p 3s, 3p 4s, 3d, 4p 5s, 4d, 5p 6s, 4f, 5d, 6p 7s, 5f, 6dPeriod 1 2 3 4 5 6 7Based on the type of electron orbitals occupied by the last elements in the periodic system is divided into blocks of s, p-block, d-block, and the block f.a. Block s: class IA and IIAS-block metal classified as active, except H and He. H classified as non-metallic, while the noble gases He classified.b. Block p: group IIIA to VIIIAP-block elements called representative because there are all kinds of metals, non-metals, and metalloids.c. Block D: group IIIB to IIBBlock D is also called transition elements, all belonging to the metal.d. Block f: lanthanides and actinides
1. The principal quantum number (n): realizing the trajectory of electrons in atoms.n has a price of 1, 2, 3, .....- N = 1 corresponds to the K shell- N = 2 correspond to the L shell- N = 3 corresponds to the skin M- And so onEach skin or any number of energy levels occupied by electrons. The number of electrons that can occupy maksimmm energy levels must satisfy the Pauli formula = 2N2.Example:skin-to-4 (n = 4) can be occupied by a maximum = 2 x 42 electrons = 32 electrons2. Azimuthal quantum number (l): indicate sub skin where the electron also shows sub skin which is a constituent of skin.Azimuthal quantum number have prices from 0 to (n-1).n = 1; l = 0; corresponding K shelln = 2, l = 0, 1; corresponding L shelln = 3; l = 0, 1, 2; appropriate skin Mn = 4; l = 0, 1, 2, 3; appropriate skin Nand so onSub leather prices vary is given a special name:l = 0; fit leather sub s (s = sharp)l = 1; fit leather sub p (p = principle)l = 2; fit leather sub d (d = diffuse)l = 3; fit leather sub f (f = fundamental)Magnetic quantum number (m): realizing the presence of one or several levels of energy in a sub shell. Magnetic quantum number (m) has a price (-l) to price (+ l).For:l = 0 (sub leather s), price m = 0 (having 1 orbital)l = 1 (p sub shell), price m = -1, O, +1 (have 3 orbitals)l = 2 (sub skin d), price m = -2, -1, O, +1, +2 (have 5 orbitals)l = 3 (sub kwit f), price m = -3, -2, O, +1, +2, +3 (has 7 orbitals)4. Spin quantum number (s): indicates the direction of rotation of the electron on its axis.In one orbital, maximum of 2 electrons can circulate and the two electron spins through the axis in the opposite direction, and each is priced spin +1 / 2 or -1 / 2.
Question : according to the theory of quantum mechanics, electrons in the atom does not have a definite orbit, why?
Kamis, 18 Oktober 2012
THERMOCHEMICAL
The enthalpy change is the change in energy that accompany chemical changes incident at a constant pressure.a. Termination of the bond requires energy (= endothermic)Example: H2 → 2H - a kJ; DH = + AKJb. Bond formation provides energy (= exothermic)Example: H2 → 2H + a kJ; DH =-a kJThe term used in the enthalpy change:1. Standard Enthalpy Pembentakan (DHF):DH animal lays to form 1 mole of compound directly from its elements were measured at 298 K and pressure of 1 atm.Example: H2 (g) + 1/2 O2 (g) → H20 (l); DHF = -285.85 kJ2. Enthalpy of decomposition:DH from the decomposition of 1 mole of the compound directly into its elements (= opposite of DH formation).Example: H2O (l) → H2 (g) + 1/2 O2 (g), DH = +285.85 kJ3. Standard Enthalpy of Combustion (DHC):DH to burn 1 mole of compound with O2 from the air measured at 298 K and pressure of 1 atm.Example: CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l); DHC = -802 kJ4. Enthalpy of reaction:DH of an equation in which substances contained in the equation is expressed in units of moles and the coefficients of the equation is simple round.Example: + 2AL 3H2SO4 → Al2 (SO4) 3 + 3H2; DH = -1468 kJ5. Enthalpy of Neutralization:DH generated (always exothermic) in acid or base neutralization reaction.Example: NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l), DH = -890.4 kJ / mol6. Lavoisier-Laplace law"The amount of heat released in the formation of one mole of a substance from the elements unsurya = amount of heat required to decompose the substance into its constituent elements."Meaning: If the reaction is reversed the sign of the heat that is formed is also reversed from positive to negative or vice versaExample:N2 (g) + 3H2 (g) → 2NH3 (g), DH = - 112 kJ2NH3 (g) → N2 (g) + 3H2 (g), DH = + 112 kJ• Enthalpy of Formation, Combustion and DecompositionThermochemical Data are generally set at a temperature of 25 0 C and a pressure of 1 atm, hereinafter referred to standard conditions. Enthalpy changes were measured at a temperature of 25 0 C and a pressure of 1 atm is called the standard enthalpy change and is expressed with the symbol Δ H 0 or ΔH298. While the changes in enthalpy measurement not refer to the condition of measurement is expressed with the symbol ΔH alone.Is the molar enthalpy of the reaction enthalpy change associated with the quantity of the substance involved in the reaction. In the known thermochemical various molar enthalpy, such as enthalpy of formation, enthalpy of decomposition, and the enthalpy of combustion.Enthalpy of FormationThere are a variety of important thermochemical equation associated with the formation of one mole of unsurunsurnya. The enthalpy change associated with this reaction is called the heat of formation or the enthalpy of formation of a given symbol ΔH f. For example, the thermochemical equation for the formation of water and steam at 100 0 C and 1 atm, respectively.
How can we use this equation to get the heat of evaporation of water? What is clear equation (1) we must reverse and then summed with the equation (2). Do not forget to change the sign of ΔH. (If the formation of H 2 O (l) exothermic, as reflected by a negative ΔH f, the reverse process must be endothermic), which means a positive exothermic which means being endothermic.Exothermic
Exothermic (heat producing)
Endothermic
If we add the equations (1) and (2), we can
And the hot reaction =
Note that the heat of reaction to all the changes with the heat of formation reaction proceeds minus the heat of formation of the reactants. In general it can be written:
Enthalpy change for reaction rates can be affected by the temperature and pressure conditions when measurements. Therefore, the necessary conditions of temperature and pressure must be specified for each data thermochemical.• Enthalpy of CombustionThe reaction of a substance with oxygen reaction called combustion. Substances that are combustible elements carbon, hydrogen, sulfur, and various compounds of these elements. Said to be perfect if the combustion of carbon (c) burned to CO2, hydrogen (H) burned into H2O, sulfur (S) burned to SO2.Enthalpy change for the combustion of 1 mol of a substance is measured at 298 K, 1 atm is called the standard enthalpy of combustion (standard enthalpy of combustion), which is expressed by Δ Hc 0. Enthalpy of combustion is also expressed in kJ mol -1.Price enthalpy of combustion of various substances at 298 K, 1 atm are given in Table 3 below.Table 3. Enthalpy of combustion of various substances at 298 K, 1 atm
Burning gasoline is an exothermic process. If gasoline is considered consisting of isooctane, C8H18 (a component of gasoline) determine the amount of heat released in the combustion of 1 liter of gasoline. Given the enthalpy of combustion of isooctane = -5460 kJ mol -1, and the density of isooktan = 0.7 kg L -1 (H = 1 and C = 12).Answer:Enthalpy of combustion of isooctane is - 5460 kJ mol -1. The mass of 1 liter of gasoline = 1 liter x 0.7 kg L-1 = 0.7 kg = 700 grams. Isooctane mole = 700 g mol -1 gram/114 = 6.14 mol. So the heat is released in the combustion of 1 liter of gasoline is: 6.14 x 5460 kJ mol = 33524.4 kJ mol -1.• Burning Perfect and ImperfectFuel combustion in vehicle engines or the industry does not burn completely. Complete combustion of hydro-carbon compounds (fossil fuels) to form carbon dioxide and water vapor. While imperfect combustion to form carbon monoxide and water vapor. For example:a. Complete combustion of isooctane:C8H18 (l) +12 ½ O2 (g) -> 8 CO2 (g) + 9 H2O (g) ΔH = -5460 kJb. Incomplete combustion of isooctane:C8H18 (l) + 8 ½ O2 (g) -> 8 CO (g) + 9 H2O (g) ΔH = -2924.4 kJThe impact is not perfect BurningAs seen in the example above, incomplete combustion produces less heat. Thus, imperfect combustion reduces fuel efficiency. Another disadvantage of incomplete combustion produces gases are carbon monoxide (CO), which are toxic. Therefore, incomplete combustion will pollute the air.• Enthalpy of DecompositionDecomposition reaction is the opposite of a reaction formation. Therefore, in accordance with the principle of conservation of energy, equal to the value of the enthalpy of decomposition enthalpy of formation, but opposite sign.Example:Given Δ Hf 0 H2O (l) = -286 kJ mol -1, the enthalpy of decomposition of H2O (l) into hydrogen gas and oxygen gas is + 286 kJ mol -1H2O (l) -> H2 (g) + ½ O2 (g) ΔH = + 286 kJ• Energy AssociationA chemical reaction involving the breaking and formation of chemical bonds. Termination of chemical bonds causing substances reagent separated into their constituent atoms. These atoms would be rearranged and regrouped to form chemical bonds in these substances the reaction products. Termination of a bond requires energy. Conversely, a bond formation would release some energy. Energy associated with the termination or formation of chemical bonds is called bond energy.Energy bond dissociation energy to be divided into compound molecules, and lattice energy for ionic compounds. Dissociation energy (D) related to the energy required to break the bond compound molecular / covalent. While the lattice energy associated with the energy released to the formation of ionic bond compound. In berikutknya discussion focused on the dissociation energy.• Institute for Energy Calculating Reaction Enthalpy ChangeAs described above, the chemical reaction will involve energy for breaking the bond between atoms bond formation between the reactants and reaction products atom. The difference between the energy for breaking and bond formation is ΔH. Can be formulated as follows:ΔHreaksi = Σ (bond energy reactants) - Σ (bonding energy of the reaction product)Consider an example of decomposition reaction H2O (endothermic reaction) and formation of CH4 (exothermic reaction) below.1. H2O decomposition reactionH2O can be broken down into gaseous H2 and O2 gases, with the help of the energy gained from the electric current.There are two stages in the reaction as shown in enthalpy diagram in Figure 2:
1. Termination 2 bond H - O into atoms H and O. energy required is equal to Σ (bond energy reagent)2. The formation of two bonds H - H and 1 O = O bond of atom H and O. the energy released is equal to Σ (bond energy reaction product).From the diagram, we see that Σ (bond energy of the reactants) <Σ (bond energy of the reaction product). Using the formula ΔH above, the obtained reaction ΔH is positive (+) or the reaction is endothermic.
2.Reaksi formation of CH4Combustion reaction CH4 with O2, CO2 and gas produced H2O
QUESTION:
mengapa (-DH/mol=+Q),and (+DH/mol= -Q) ?
Selasa, 16 Oktober 2012
stoichiometric
Stoichiometry
is the branch of chemistry that studies the quantitative relationship
of the composition of chemical substances and reactions.1. LAW OF CONSERVATION OF MASS = Lavoisier LAW"The mass of substances before and after the reaction is fixed".Example:hydrogen oxide hydrogen + oxygen
(4g) (32g) (36g)2. COMPARATIVE LAW = LEGAL PERMANENT Proust"Comparison of the mass of the elements in each compound is fixed"Example:a. In the compound NH3: N mass: mass of HAr = 1. N: 3 Ar. H= 1 (14): 3 (1) = 14: 3b. On the compound SO3: S mass: mass 0Ar = 1. S: 3 Ar. O= 1 (32): 3 (16) = 32: 48 = 2: 3Advantages of the law Proust:if known mass of a compound or a mass of one of the elements that make up the compound make-masses of other elements can be determined.Example:How many levels of C in 50 grams of CaCO3? (Ar: C = 12; 0 = 16; Ca = 40)Mass C = (Ar C / Mr CaCO3) x mass of CaCO3= 12/100 x 50 grams = 6 gramsmass CLevels of C = mass C / mass x 100% CaCO3= 6/50 x 100% = 12%3. COMPARATIVE LAW LAW MULTIPLE = DALTON"When the two elements can form two or more compounds to the mass of one element as much the second element of the mass ratio in value as integers and simple".Example:If the element nitrogen fertilized den oxygen can be formed,NO where mass N: 0 = 14: 16 = 7: 8NO2 which the mass N: 0 = 14: 32 = 7: 16For the same amount of nitrogen mass ratio of the mass of oxygen in the compound NO: NO2 = 8: 16 = 1: 2GAS LAWSTo apply the ideal gas equation: PV = nRTwhere:P = gas pressure (atmospheric)V = gas volume (liters)n = moles of gasR = universal gas constant = 0082 lt.atm / mol KelvinT = absolute temperature (Kelvin)The changes of P, V and T from state 1 to state 2 with certain conditions reflected by the following laws:A.BOYLE LAWThis law is derived from the ideal gas equation of state withn1 = n2 and T1 = T2; thus obtained: P1 V1 = P2 V2Example:What is the pressure of 0 5 mol O2 with a volume of 10 liters when the temperature is 0.5 mol NH3 has a volume of 5 liters den 2 atmospheric pressure?Answer:P1 V1 = P2 V22.5 = P2. 10 P2 = 1 atmosphereB. LEGAL Gay-Lussac"The volume of gases that react den gas volume bile reaction products were measured at the same temperature and pressure, will be compared as integers modest den".So for: P1 = P2 and T1 = T2 holds: V1 / V2 = n1 / n2Example:Calculate the mass of 10 liters of nitrogen gas (N2) if the condition is 1 liter of hydrogen gas (H2) mass of 0.1 g.Given: Ar for H = 1 and N = 14Answer: V1/V2 = n1/n2 10/1 = (x/28) / (0.1 / 2) x = 14 gramsSo mass = 14 grams of nitrogen gas.C. BOYLE LAW-Gay LussacThis law is an extension of the previous law is spoken with the state price den n = n2 to obtain the equation:P1. V1 / T1 = P2. V2 / T2D. Avogadro's law"At the same temperature and pressure, gases equal volume containing the same number of moles. From this statement it is determined that the state of STP (0o C 1 atm) 1 mole of any gas volume of 22.4 liters of volume is referred to as the molar volume of gas.Example:What volume of 8.5 grams of ammonia (NH3) at a temperature of 27o C and a pressure of 1 atm?(Ar: H = 1, N = 14)Answer:85 g of ammonia = 17 mol = 0.5 molThe volume of ammonia (STP) = 0.5 x 4.22 = 2.11 litersAccording to Boyle-Gay Lussac equation:P1. V1 / T1 = P2. V2 / T21 x 112.1 / 273 = 1 x V2 / (273 + 27) liter V2 = 12:31
in chemistry, stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the study and calculate the quantitative relationships of the reactants and products in chemical reactions (chemical equations). The word is derived from the Greek stoikheion (elements) and metriā (size).Stoichiometry is based on the fundamental laws of chemistry, the law of conservation of mass, the law of comparative fixed, and multiple comparative law.Example:
Stoichiometric gas is a particular form, in which the reactants and products entirely in the form of gas. In this case, the coefficient of substance (mole ratio stating the reaction stoichiometry) also has stated volume ratio between the substances involved. a. The initial phase of stoichiometricAt the beginning of chemistry, quantitative aspects of chemical change, the chemical reaction stoichiometry, did not get much attention. Even when attention has been given, experimental techniques and tools do not produce correct results.One example involves the theory of phlogiston. Flogistonis tried to explain the phenomenon of combustion with the term "flammable substance". According to the flogitonis, arson is a release of a substance can be etrbakar (from the burning substance). This substance was later called "phlogiston". Based on this theory, they defined as the release of phlogiston combustion of flammable substances. Mass changes when burning wood fits well with this theory. However, the change in mass of metal when calcined does not match the theory. However flogistonis accept that the two processes are essentially identical. Increasing the mass of calcined metal is a fact. Flogistonis tried to explain this anomaly by stating that phlogiston negative mass.Philosophers of Flanders January Baptista van Helmont (1579-1644) experimented "willow" famous. He is growing seedlings of willow after measuring the mass of flower pots and soil. Since there is no mass change flower pots and soil when the seed grows, it assumes that the masses were obtained only because of water coming into the ore. He concludes that "the root of all matter is water". Based on the current outlook, hypothesis and experiment are far from perfect, but the theory is a good example of the attitude of the quantitative aspects of chemistry that are growing. Helmont recognize the importance of stoichiometry, and clearly ahead of his time.In the late 18th century, German chemist Jeremias Benjamin Richter (1762-1807) invented the concept of equivalent (in terms of modern chemistry chemical equivalent) with a reaction carefully acid / base, the quantitative relationship between acids and bases in the neutralization reaction. Equivalent Richter, or what is now called the chemical equivalent, indicating a certain amount of material in the reaction. The neutralization equivalent in regard to the relationship between the number of acid and a base for mentralkannya. Proper knowledge is essential to produce the equivalent of soap and gunpowder good. Thus, such knowledge is very important in practice.At the same time Lavoisier established the law of conservation of mass, and provide a basis equivalent to the concept of an accurate and creative experiments. Thus, the stoichiometry handle the quantitative aspects of chemical reactions into chemical basic methodology. All the fundamental laws of chemistry, of the law of conservation of mass, the law of comparative law remains until all based gas reaction stoichiometry. Fundamental laws are the basis of the atomic theory, and consistently explained by atomic theory. However, it is interesting to note that the concept of equivalent used before atomic theory was introduced.b. The relative atomic mass and atomic massDalton recognized that it is important to determine the mass of each atom as mass varies for each type of atom. Atom is very small so it is not possible to determine the mass of a single atom. So he focuses on the relative masses and create a table atomic mass (Figure 1.3) for the first time in human history. In the table, the mass of the lightest element, hydrogen adoption as a standard one (H = 1). Atomic mass is a relative value, meaning that a dimensionless ratio. Although several different atomic masses with modern values, most of the proposed values in the range of compatibility with the current value. This shows that the idea and the experiment right.Then the Swedish chemist Jons Jakob Berzelius Baron (1779-1848) to determine the mass of the oxygen atom as the standard (O = 100). Because Berzelius get this value based on the analysis of oxide, it has a clear reason to choose oxygen as standard. However, the standard hydrogen is clearly superior in terms of simplicity. Now, after much discussion and modification, carbon standard is used. In this method, the mass of 12C carbon with 6 protons and 6 neutrons is defined as 12.0000. Atomic mass is the mass of an atom relative to this standard. Although carbon has been declared as standard, this can actually be considered as a standard hydrogen is modified.Problem Exercise 1.1 Change due to change in the standard atomic mass. Calculate the mass of hydrogen and carbon atoms by the standards of Berzelius (O = 100). Please answer using one decimal place.Answer.The mass of hydrogen atoms = 1 x (100/16) = 6.25 (6.3), the mass of carbon atoms = 12 x (100/16) = 75.0Atomic mass of almost all the elements very close to integers, ie integer multiples of hydrogen atomic mass. This is a natural kosekuensi fact that the hydrogen atom mass equal to the mass of a proton, which in turn is almost equal to the mass of a neutron, and electron mass is very small to negligible. However, most of the naturally occurring element that is a mixture of several isotopes, and atomic mass depends on the distribution of isotopes. For example, the atomic mass of hydrogen and oxygen is 1.00704 and 15.9994. The mass of the oxygen atom is very close to the value of 16 is a bit smaller.Solved Problem 1.2 Example Calculation of atomic mass. Calculate the atomic mass of magnesium using the following distribsui isotopes: 24Mg: 78.70%, 25 mg: 10.13%, 26Mg: 11.17%.Answer:0.7870 x 24 + 0.1013 +0.1117 x 25 x 26 = 18.89 +2.533 +2.904 = 24.327 (amu; see section 1.3 (e))Atomic mass of Mg = 18.89 + 2.533 + 2.904 = 24,327 (amu).A small difference of atomic masses found on the periodic table (24 305) the result of differences in the way in round numbers.Molecular mass and formula massEach compound is defined enumerated by a chemical formula that indicates the type and number of atoms menyususn compound. The mass formula (or formula mass) is defined as the sum of the atomic masses based on the type and number of atoms in the chemical formula defined. The chemical formula of molecules called molecular formula, chemical formula and mass is called the mass molekul.5 example, the molecular formula of carbon dioxide is CO2, and the molecular mass is 12 + (2x 6) = 44. As the mass of the atom, both mass and molecular mass formula should not be an integer. For example, the molecular mass of hydrogen chloride HCl is 36.5. Even if the type and number of atoms that make up molecules are identical, the two molecules may have different molecular masses when there are different isostop involved.It is impossible to define molecules for compounds such as sodium chloride. Mass formula for sodium chloride is used instead of molecular mass.Example Problem 1.3 mokelul containing molecular mass of the isotope.Calculate the molecular mass of water H2O and D2O heavy water (2H2O) in integers.AnswerMolecular mass of H2O = 1 x 2 + 16 = 18, D2O molecular mass = (2 x 2) + 16 = 20The difference in molecular mass of H2O and D2O are very substantial, and these differences are physical and chemical properties anatara both types of compounds can not be ignored. H2O than D2O electrolysed easier. Thus, the remaining water after electrolysis tends to contain more D2O than in natural water.d. Quantity of matter and moleQuantitative methods most suited to express the amount of matter is the number of particles such as atoms, molecules that make up the material being discussed. However, to calculate the atomic or molecular particles are very small and can not be seen very difficult. Instead of counting the number of particles is directly the number of particles, we can use the mass of a certain number of particles. Then, how does a certain amount of numbers chosen? Forlong story short, the number of particles in a 22.4 L of gas at STP (0 ℃, 1ATM) was selected as the standard amount. This number is called Avogadro's number. Name number Loschmidt also proposed to honor the Austrian chemist Joseph Loschmidt (1821-1895) who first with the experiment (1865).Since 1962, according to the SI (Systeme Internationale) decided bahwam in the world of chemistry, mole is used as a unit of the amount of matter. Defined Avogadro's number of carbon atoms in 12 g 126C and renamed Avogadro constant.There are several definitions of "mole":(I) The amount of material that contains a number of particles contained in 12 g of 12C. (Ii) one mole of material that contains Avogadro constant number of particles.(Iii) A material that contains 6.02 x 1023 particles in one mole.e. Atomic mass units (sma)Because the standard atomic mass is the mass of hydrogen Dalton system, standard mass in the right SI 1/12 the mass of 12C. This value is called the atomic mass unit (sma) and is equal to 1.6605402 x 10-27 kg, and D (Dalton) is used as a symbol. Atomic mass is defined as the ratio of the average sma elements with natural isotopic distribution with 1/12 sma 12C
question:
in law charles (at trial balloon), if a balloon is inserted into the refrigerator can be deflated, whereas when heated can expand, why is that???
(4g) (32g) (36g)2. COMPARATIVE LAW = LEGAL PERMANENT Proust"Comparison of the mass of the elements in each compound is fixed"Example:a. In the compound NH3: N mass: mass of HAr = 1. N: 3 Ar. H= 1 (14): 3 (1) = 14: 3b. On the compound SO3: S mass: mass 0Ar = 1. S: 3 Ar. O= 1 (32): 3 (16) = 32: 48 = 2: 3Advantages of the law Proust:if known mass of a compound or a mass of one of the elements that make up the compound make-masses of other elements can be determined.Example:How many levels of C in 50 grams of CaCO3? (Ar: C = 12; 0 = 16; Ca = 40)Mass C = (Ar C / Mr CaCO3) x mass of CaCO3= 12/100 x 50 grams = 6 gramsmass CLevels of C = mass C / mass x 100% CaCO3= 6/50 x 100% = 12%3. COMPARATIVE LAW LAW MULTIPLE = DALTON"When the two elements can form two or more compounds to the mass of one element as much the second element of the mass ratio in value as integers and simple".Example:If the element nitrogen fertilized den oxygen can be formed,NO where mass N: 0 = 14: 16 = 7: 8NO2 which the mass N: 0 = 14: 32 = 7: 16For the same amount of nitrogen mass ratio of the mass of oxygen in the compound NO: NO2 = 8: 16 = 1: 2GAS LAWSTo apply the ideal gas equation: PV = nRTwhere:P = gas pressure (atmospheric)V = gas volume (liters)n = moles of gasR = universal gas constant = 0082 lt.atm / mol KelvinT = absolute temperature (Kelvin)The changes of P, V and T from state 1 to state 2 with certain conditions reflected by the following laws:A.BOYLE LAWThis law is derived from the ideal gas equation of state withn1 = n2 and T1 = T2; thus obtained: P1 V1 = P2 V2Example:What is the pressure of 0 5 mol O2 with a volume of 10 liters when the temperature is 0.5 mol NH3 has a volume of 5 liters den 2 atmospheric pressure?Answer:P1 V1 = P2 V22.5 = P2. 10 P2 = 1 atmosphereB. LEGAL Gay-Lussac"The volume of gases that react den gas volume bile reaction products were measured at the same temperature and pressure, will be compared as integers modest den".So for: P1 = P2 and T1 = T2 holds: V1 / V2 = n1 / n2Example:Calculate the mass of 10 liters of nitrogen gas (N2) if the condition is 1 liter of hydrogen gas (H2) mass of 0.1 g.Given: Ar for H = 1 and N = 14Answer: V1/V2 = n1/n2 10/1 = (x/28) / (0.1 / 2) x = 14 gramsSo mass = 14 grams of nitrogen gas.C. BOYLE LAW-Gay LussacThis law is an extension of the previous law is spoken with the state price den n = n2 to obtain the equation:P1. V1 / T1 = P2. V2 / T2D. Avogadro's law"At the same temperature and pressure, gases equal volume containing the same number of moles. From this statement it is determined that the state of STP (0o C 1 atm) 1 mole of any gas volume of 22.4 liters of volume is referred to as the molar volume of gas.Example:What volume of 8.5 grams of ammonia (NH3) at a temperature of 27o C and a pressure of 1 atm?(Ar: H = 1, N = 14)Answer:85 g of ammonia = 17 mol = 0.5 molThe volume of ammonia (STP) = 0.5 x 4.22 = 2.11 litersAccording to Boyle-Gay Lussac equation:P1. V1 / T1 = P2. V2 / T21 x 112.1 / 273 = 1 x V2 / (273 + 27) liter V2 = 12:31
in chemistry, stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the study and calculate the quantitative relationships of the reactants and products in chemical reactions (chemical equations). The word is derived from the Greek stoikheion (elements) and metriā (size).Stoichiometry is based on the fundamental laws of chemistry, the law of conservation of mass, the law of comparative fixed, and multiple comparative law.Example:
Stoichiometric gas is a particular form, in which the reactants and products entirely in the form of gas. In this case, the coefficient of substance (mole ratio stating the reaction stoichiometry) also has stated volume ratio between the substances involved. a. The initial phase of stoichiometricAt the beginning of chemistry, quantitative aspects of chemical change, the chemical reaction stoichiometry, did not get much attention. Even when attention has been given, experimental techniques and tools do not produce correct results.One example involves the theory of phlogiston. Flogistonis tried to explain the phenomenon of combustion with the term "flammable substance". According to the flogitonis, arson is a release of a substance can be etrbakar (from the burning substance). This substance was later called "phlogiston". Based on this theory, they defined as the release of phlogiston combustion of flammable substances. Mass changes when burning wood fits well with this theory. However, the change in mass of metal when calcined does not match the theory. However flogistonis accept that the two processes are essentially identical. Increasing the mass of calcined metal is a fact. Flogistonis tried to explain this anomaly by stating that phlogiston negative mass.Philosophers of Flanders January Baptista van Helmont (1579-1644) experimented "willow" famous. He is growing seedlings of willow after measuring the mass of flower pots and soil. Since there is no mass change flower pots and soil when the seed grows, it assumes that the masses were obtained only because of water coming into the ore. He concludes that "the root of all matter is water". Based on the current outlook, hypothesis and experiment are far from perfect, but the theory is a good example of the attitude of the quantitative aspects of chemistry that are growing. Helmont recognize the importance of stoichiometry, and clearly ahead of his time.In the late 18th century, German chemist Jeremias Benjamin Richter (1762-1807) invented the concept of equivalent (in terms of modern chemistry chemical equivalent) with a reaction carefully acid / base, the quantitative relationship between acids and bases in the neutralization reaction. Equivalent Richter, or what is now called the chemical equivalent, indicating a certain amount of material in the reaction. The neutralization equivalent in regard to the relationship between the number of acid and a base for mentralkannya. Proper knowledge is essential to produce the equivalent of soap and gunpowder good. Thus, such knowledge is very important in practice.At the same time Lavoisier established the law of conservation of mass, and provide a basis equivalent to the concept of an accurate and creative experiments. Thus, the stoichiometry handle the quantitative aspects of chemical reactions into chemical basic methodology. All the fundamental laws of chemistry, of the law of conservation of mass, the law of comparative law remains until all based gas reaction stoichiometry. Fundamental laws are the basis of the atomic theory, and consistently explained by atomic theory. However, it is interesting to note that the concept of equivalent used before atomic theory was introduced.b. The relative atomic mass and atomic massDalton recognized that it is important to determine the mass of each atom as mass varies for each type of atom. Atom is very small so it is not possible to determine the mass of a single atom. So he focuses on the relative masses and create a table atomic mass (Figure 1.3) for the first time in human history. In the table, the mass of the lightest element, hydrogen adoption as a standard one (H = 1). Atomic mass is a relative value, meaning that a dimensionless ratio. Although several different atomic masses with modern values, most of the proposed values in the range of compatibility with the current value. This shows that the idea and the experiment right.Then the Swedish chemist Jons Jakob Berzelius Baron (1779-1848) to determine the mass of the oxygen atom as the standard (O = 100). Because Berzelius get this value based on the analysis of oxide, it has a clear reason to choose oxygen as standard. However, the standard hydrogen is clearly superior in terms of simplicity. Now, after much discussion and modification, carbon standard is used. In this method, the mass of 12C carbon with 6 protons and 6 neutrons is defined as 12.0000. Atomic mass is the mass of an atom relative to this standard. Although carbon has been declared as standard, this can actually be considered as a standard hydrogen is modified.Problem Exercise 1.1 Change due to change in the standard atomic mass. Calculate the mass of hydrogen and carbon atoms by the standards of Berzelius (O = 100). Please answer using one decimal place.Answer.The mass of hydrogen atoms = 1 x (100/16) = 6.25 (6.3), the mass of carbon atoms = 12 x (100/16) = 75.0Atomic mass of almost all the elements very close to integers, ie integer multiples of hydrogen atomic mass. This is a natural kosekuensi fact that the hydrogen atom mass equal to the mass of a proton, which in turn is almost equal to the mass of a neutron, and electron mass is very small to negligible. However, most of the naturally occurring element that is a mixture of several isotopes, and atomic mass depends on the distribution of isotopes. For example, the atomic mass of hydrogen and oxygen is 1.00704 and 15.9994. The mass of the oxygen atom is very close to the value of 16 is a bit smaller.Solved Problem 1.2 Example Calculation of atomic mass. Calculate the atomic mass of magnesium using the following distribsui isotopes: 24Mg: 78.70%, 25 mg: 10.13%, 26Mg: 11.17%.Answer:0.7870 x 24 + 0.1013 +0.1117 x 25 x 26 = 18.89 +2.533 +2.904 = 24.327 (amu; see section 1.3 (e))Atomic mass of Mg = 18.89 + 2.533 + 2.904 = 24,327 (amu).A small difference of atomic masses found on the periodic table (24 305) the result of differences in the way in round numbers.Molecular mass and formula massEach compound is defined enumerated by a chemical formula that indicates the type and number of atoms menyususn compound. The mass formula (or formula mass) is defined as the sum of the atomic masses based on the type and number of atoms in the chemical formula defined. The chemical formula of molecules called molecular formula, chemical formula and mass is called the mass molekul.5 example, the molecular formula of carbon dioxide is CO2, and the molecular mass is 12 + (2x 6) = 44. As the mass of the atom, both mass and molecular mass formula should not be an integer. For example, the molecular mass of hydrogen chloride HCl is 36.5. Even if the type and number of atoms that make up molecules are identical, the two molecules may have different molecular masses when there are different isostop involved.It is impossible to define molecules for compounds such as sodium chloride. Mass formula for sodium chloride is used instead of molecular mass.Example Problem 1.3 mokelul containing molecular mass of the isotope.Calculate the molecular mass of water H2O and D2O heavy water (2H2O) in integers.AnswerMolecular mass of H2O = 1 x 2 + 16 = 18, D2O molecular mass = (2 x 2) + 16 = 20The difference in molecular mass of H2O and D2O are very substantial, and these differences are physical and chemical properties anatara both types of compounds can not be ignored. H2O than D2O electrolysed easier. Thus, the remaining water after electrolysis tends to contain more D2O than in natural water.d. Quantity of matter and moleQuantitative methods most suited to express the amount of matter is the number of particles such as atoms, molecules that make up the material being discussed. However, to calculate the atomic or molecular particles are very small and can not be seen very difficult. Instead of counting the number of particles is directly the number of particles, we can use the mass of a certain number of particles. Then, how does a certain amount of numbers chosen? Forlong story short, the number of particles in a 22.4 L of gas at STP (0 ℃, 1ATM) was selected as the standard amount. This number is called Avogadro's number. Name number Loschmidt also proposed to honor the Austrian chemist Joseph Loschmidt (1821-1895) who first with the experiment (1865).Since 1962, according to the SI (Systeme Internationale) decided bahwam in the world of chemistry, mole is used as a unit of the amount of matter. Defined Avogadro's number of carbon atoms in 12 g 126C and renamed Avogadro constant.There are several definitions of "mole":(I) The amount of material that contains a number of particles contained in 12 g of 12C. (Ii) one mole of material that contains Avogadro constant number of particles.(Iii) A material that contains 6.02 x 1023 particles in one mole.e. Atomic mass units (sma)Because the standard atomic mass is the mass of hydrogen Dalton system, standard mass in the right SI 1/12 the mass of 12C. This value is called the atomic mass unit (sma) and is equal to 1.6605402 x 10-27 kg, and D (Dalton) is used as a symbol. Atomic mass is defined as the ratio of the average sma elements with natural isotopic distribution with 1/12 sma 12C
question:
in law charles (at trial balloon), if a balloon is inserted into the refrigerator can be deflated, whereas when heated can expand, why is that???
Minggu, 07 Oktober 2012
chemical reaction
A chemical reaction is a natural process that always produces antarubahan chemical compounds. [1] The compound or compounds early in the reaction is referred to as the reactants. Chemical reactions are usually characterized by a chemical change, and will produce one or more products that typically have characteristics that are different from the reactants. Classically, chemical reactions involve changes involving the movement of electrons in the forming and breaking of chemical bonds, although the general concept is basically a chemical reaction can also be applied to the transformation of elementary particles such as the nuclear reaction.
Reactions with different chemical used in chemical synthesis to produce the desired compound. In biochemistry, series of chemical reactions catalyzed by enzymes form metabolic pathways, in which the synthesis and decomposition is usually not possible in the cell do.
In the late 1890s, Scottish chemist Sir William Ramsay discovered the element helium, neon, argon, krypton, and xenon. These elements, along with radon, placed in group VIIIA of the periodic table and called inert (or noble) gases because of their tendency to not react with other elements (see pages our periodic table). The tendency for the noble gases do not react with other elements to do with their electron configuration. All noble gases have a full valence shell, this configuration is a stable configuration and one of the other elements are trying to achieve by reacting together. In other words, the reason atoms react with each other is to reach a state where they are filled valence shell.Let's look at the reaction of sodium with chlorine. In the countries of their atoms, sodium has one valence electron and chlorine has seven.sodium-E configuration with chlorineSodium ChlorineChlorine, with seven valence electrons, needs one extra electron to complete the valence shell with eight electrons. Sodium is a bit tricky. At first it seemed that the sodium needed seven additional electrons to complete its valence shell. But this will give sodium -7 electric charge and makes it very balanced in terms of the number of electrons (negative charge) relative to the number of protons (positive charge). Apparently, it is much easier to give the sodium valence electrons and become ions +1. Thus, the sodium atom emptying third electron shell and now the outer shell containing electrons, the second shell, filled - agrees with our previous statement that atoms react as they try to fill their valence shell.sodium chloride - Sodium ChlorideSodium ChlorideThis trait, the tendency to lose electrons when entering a chemical reaction, it is common for all metals. The number of electrons of metal atoms will lose (and they will take the charge) is equal to the number of electrons in the valence shell of atoms. For all the elements in Group A of the periodic table, the number of valence electrons is equal to the number of groups (see pages our periodic table).Nonmetals, by comparison, tend to gain electrons (or share) to complete their valence shells. For all nonmetals except hydrogen and helium, they are complete with eight valence shell electrons. Therefore, nonmetals gain electrons in accordance with the formula = 8 - (group #). Chlorine, in a group of 7, will get 8-7 = 1 electron to form -1 ions.Hydrogen and helium have only electron in their first electron shell. The capacity of this shell is two. So helium, with two electrons, already has a full valence shell and crashed into a group of elements that are less likely to react with others, noble gases. Hydrogen, with one valence electron, will gain one electron when forming negative ions. However, hydrogen and metalloid elements on the periodic table labeled, can actually be a positive or negative ions are formed in accordance with the number of valence electrons they have. So hydrogen will form +1 ions when it loses one electron and ion -1 when gains one electron.Reaction energyAll chemical reactions are accompanied by energy changes. Some reactions release energy to their surroundings (usually in the form of heat) and is called exothermic. For example, sodium and chlorine react so hard that the fire can be seen as an exothermic reaction give off heat. On the other hand, some reactions need to absorb heat from their environment to continue. These reactions are called endothermic. A good example of an endothermic reaction is occurring in an instant '"cold pack." Commercial cold packs usually consist of two compounds - urea and ammonium chloride in a separate container in a plastic bag. When the bag is bent and damaged containers in two compounds mix together and begin to react. Because endothermic, absorbing heat from the surrounding environment and the bags get cold.The reaction was followed immediately when the two substances are mixed together (like the reaction of sodium with chlorine or urea with ammonium chloride) is called a spontaneous reaction. Not all reactions proceed spontaneously. For example, think about the game. When you strike a match you cause a reaction between the chemicals in the match head and the oxygen in the air. The match will not ignite spontaneously, though. You must first input of energy, called the activation energy of the reaction. In the case of a match, you supply the activation energy in the form of heat to light a match in the match, after activation energy is absorbed and the reaction starts, the reaction continues until you either extinguish the fire or you run out of material to react.
Types of chemical reactions
The diversity of chemical reactions and approaches taken in the study resulted in many ways to classify these reactions, which often overlap. Below are examples of classification of chemical reactions that are normally used.
• Isomerization, which are chemical compounds undergo structural rearrangement without any change in the composition of the atom
• Direct Combination or synthesis, in which two or more elements or compounds unite to form complex products: 3H2 + N2 → 2 NH3
• Decomposition kimiawiatauanalisis, In which a compound is broken down into smaller compounds: 2H2O → 2 H2 + O2
• Replacement tunggalatausubstitusi, at Characterize by an element is replaced by a more reactive element: 2 Na (s) + 2 HCl (aq) → 2 NaCl (aq) + H 2 (g)
• MetatesisatauReaksi double replacement, In which two ionic compounds or bond mutual changed to form different compounds: NaCl (aq) + AgNO3 (aq) → NaNO3 (aq) + AgCl (s)
• Reaksiasam base, widely is the reaction between an acid with a base. It has various definitions depending on the acid-base concepts digunakan.Beberapa most common definition is:
oDefinisiArrhenius: acid dissociates in water releasing H3O + ion; Bases dissociate in water releasing OH-ions
. ODefinisiBrønsted-Lowry: acid is a proton donor (H +) donors; bases is the recipient (acceptor) proton. Surrounding the Arrhenius definition.oDefinisiLewis: Acids are electron pair acceptors; bases are electron pair donors. This definition covers the Brønsted-Lowry definition.
• Redox reactions, in which a change in the oxidation compounds reacting atoms. This reaction can be interpreted as an electron transfer. Examples of redox reactions are: 2 S2O32-(aq) + I2 (aq) → S4O62-(aq) + 2 I-(aq), Which I2reduced to I-and S2O32-(Aniontiosulfat) oxidized menjadiS4O62-.
• Burning, is a kind of redox reaction in which materials can ignite join elements of an oxidant, usually oxygen, to generate heat and form oxidized products. Combustion term usually used to refer only to the large-scale oxidation of whole molecules. Controlled oxidation of only one single functional group is not included in the pembakaran.C10H18 + 12 O2 → 10 CO2 + 4 H2OCH2S + 6 F2 → CF4 + 2HF + SF 6
• Organic Reactions, covers various types of reactions involving compounds which have carbon as the main element.
QUESTION :
Reactions with different chemical used in chemical synthesis to produce the desired compound. In biochemistry, series of chemical reactions catalyzed by enzymes form metabolic pathways, in which the synthesis and decomposition is usually not possible in the cell do.
In the late 1890s, Scottish chemist Sir William Ramsay discovered the element helium, neon, argon, krypton, and xenon. These elements, along with radon, placed in group VIIIA of the periodic table and called inert (or noble) gases because of their tendency to not react with other elements (see pages our periodic table). The tendency for the noble gases do not react with other elements to do with their electron configuration. All noble gases have a full valence shell, this configuration is a stable configuration and one of the other elements are trying to achieve by reacting together. In other words, the reason atoms react with each other is to reach a state where they are filled valence shell.Let's look at the reaction of sodium with chlorine. In the countries of their atoms, sodium has one valence electron and chlorine has seven.sodium-E configuration with chlorineSodium ChlorineChlorine, with seven valence electrons, needs one extra electron to complete the valence shell with eight electrons. Sodium is a bit tricky. At first it seemed that the sodium needed seven additional electrons to complete its valence shell. But this will give sodium -7 electric charge and makes it very balanced in terms of the number of electrons (negative charge) relative to the number of protons (positive charge). Apparently, it is much easier to give the sodium valence electrons and become ions +1. Thus, the sodium atom emptying third electron shell and now the outer shell containing electrons, the second shell, filled - agrees with our previous statement that atoms react as they try to fill their valence shell.sodium chloride - Sodium ChlorideSodium ChlorideThis trait, the tendency to lose electrons when entering a chemical reaction, it is common for all metals. The number of electrons of metal atoms will lose (and they will take the charge) is equal to the number of electrons in the valence shell of atoms. For all the elements in Group A of the periodic table, the number of valence electrons is equal to the number of groups (see pages our periodic table).Nonmetals, by comparison, tend to gain electrons (or share) to complete their valence shells. For all nonmetals except hydrogen and helium, they are complete with eight valence shell electrons. Therefore, nonmetals gain electrons in accordance with the formula = 8 - (group #). Chlorine, in a group of 7, will get 8-7 = 1 electron to form -1 ions.Hydrogen and helium have only electron in their first electron shell. The capacity of this shell is two. So helium, with two electrons, already has a full valence shell and crashed into a group of elements that are less likely to react with others, noble gases. Hydrogen, with one valence electron, will gain one electron when forming negative ions. However, hydrogen and metalloid elements on the periodic table labeled, can actually be a positive or negative ions are formed in accordance with the number of valence electrons they have. So hydrogen will form +1 ions when it loses one electron and ion -1 when gains one electron.Reaction energyAll chemical reactions are accompanied by energy changes. Some reactions release energy to their surroundings (usually in the form of heat) and is called exothermic. For example, sodium and chlorine react so hard that the fire can be seen as an exothermic reaction give off heat. On the other hand, some reactions need to absorb heat from their environment to continue. These reactions are called endothermic. A good example of an endothermic reaction is occurring in an instant '"cold pack." Commercial cold packs usually consist of two compounds - urea and ammonium chloride in a separate container in a plastic bag. When the bag is bent and damaged containers in two compounds mix together and begin to react. Because endothermic, absorbing heat from the surrounding environment and the bags get cold.The reaction was followed immediately when the two substances are mixed together (like the reaction of sodium with chlorine or urea with ammonium chloride) is called a spontaneous reaction. Not all reactions proceed spontaneously. For example, think about the game. When you strike a match you cause a reaction between the chemicals in the match head and the oxygen in the air. The match will not ignite spontaneously, though. You must first input of energy, called the activation energy of the reaction. In the case of a match, you supply the activation energy in the form of heat to light a match in the match, after activation energy is absorbed and the reaction starts, the reaction continues until you either extinguish the fire or you run out of material to react.
Types of chemical reactions
The diversity of chemical reactions and approaches taken in the study resulted in many ways to classify these reactions, which often overlap. Below are examples of classification of chemical reactions that are normally used.
• Isomerization, which are chemical compounds undergo structural rearrangement without any change in the composition of the atom
• Direct Combination or synthesis, in which two or more elements or compounds unite to form complex products: 3H2 + N2 → 2 NH3
• Decomposition kimiawiatauanalisis, In which a compound is broken down into smaller compounds: 2H2O → 2 H2 + O2
• Replacement tunggalatausubstitusi, at Characterize by an element is replaced by a more reactive element: 2 Na (s) + 2 HCl (aq) → 2 NaCl (aq) + H 2 (g)
• MetatesisatauReaksi double replacement, In which two ionic compounds or bond mutual changed to form different compounds: NaCl (aq) + AgNO3 (aq) → NaNO3 (aq) + AgCl (s)
• Reaksiasam base, widely is the reaction between an acid with a base. It has various definitions depending on the acid-base concepts digunakan.Beberapa most common definition is:
oDefinisiArrhenius: acid dissociates in water releasing H3O + ion; Bases dissociate in water releasing OH-ions
. ODefinisiBrønsted-Lowry: acid is a proton donor (H +) donors; bases is the recipient (acceptor) proton. Surrounding the Arrhenius definition.oDefinisiLewis: Acids are electron pair acceptors; bases are electron pair donors. This definition covers the Brønsted-Lowry definition.
• Redox reactions, in which a change in the oxidation compounds reacting atoms. This reaction can be interpreted as an electron transfer. Examples of redox reactions are: 2 S2O32-(aq) + I2 (aq) → S4O62-(aq) + 2 I-(aq), Which I2reduced to I-and S2O32-(Aniontiosulfat) oxidized menjadiS4O62-.
• Burning, is a kind of redox reaction in which materials can ignite join elements of an oxidant, usually oxygen, to generate heat and form oxidized products. Combustion term usually used to refer only to the large-scale oxidation of whole molecules. Controlled oxidation of only one single functional group is not included in the pembakaran.C10H18 + 12 O2 → 10 CO2 + 4 H2OCH2S + 6 F2 → CF4 + 2HF + SF 6
• Organic Reactions, covers various types of reactions involving compounds which have carbon as the main element.
QUESTION :
- why Na with water can explode while the kerosene can not???
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