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ChemExam 2

Ch.5, 19, 15

The law of conservation of mass States that matter can be neither created nor destroyed it explains why equations must balance and is the basis for stoichiometry and equilibrium calculations
The law of conservation of energy States that energy can be neither created nor destroyed; energy takes various forms that can be converted from one to the other
Thermodynamics Independent of path (All state functions); uses the gibb's free energy equation ^G=^H-T^S; Used to describe whether the overall properties will or not will happen (spontaneity)
Thermochemistry A branch of thermodynamics which focuses on the study of heat given or absorbed in a chemical reaction.
Temperature An intensive property of matter; a quantitive measurement of the degree to which an object is either "hot" or "cold"....it is not heat. There are three scales: Fahrenheit, Celsius, and Kelvin.
Thermochemical standard state conditions -T=25C=298K -P=1 atm -Concentration=1 M
Thermochemical standard states of matter -For pure substances in their liquid or solid phase the standard state is the pure liquid or solid -For gases 1 atm of pressure -For gaseous mixtures 1 atm -For aqueos solutions 1 M concentration
Closed system Can exchange energy but not matter with its surroundings
Open system Exchanges energy and matter with its surroundings
Isolated system Doesn't exchange energy and matter with its surroundings
State function The property of a system that depends only on the present state of the system and not on its history; doesn't depend on the pathway used (indep. of path) -T(temperature), P(pressure), V(volume), ^E(change in energy), ^H(change in enthalpy), ^S(entropy)
Non-state function -n (moles), q (heat), w (work), d (distance)
Sensible heat Heat that can be detected by a change in the temperature of a system
Latent heat Heat that cannot be detected because there is no change in temperature of the system. e.g. The heat that is used to melt ice or to evaporate water
Heat of fusion The heat that must be absorbed to melt a mole of a solid e.g. melting ice to liquid water
Heat of vaporization The heat that must be absorbed to boil a mole of a liquid e.g. boiling liquid water to steam
Thermochemical equations Are balanced chemical reaction plus the ^H value for the reaction
Heat(q) A form of energy associated with the random motion of the elementary particles in matter
Heat capacity the amount of heat needed to raise the temperature of a defined amount of a pure substance by one degree
Specific heat The amount of heat needed to raise the temperature of one gram of a substance by 1C (or 1 K)...unit is (J/g*K)
Calorie The specific heat of water= 4.184 (J/g*K)
Molar heat capacity The amount of heat required to raise the temperature of one mole of a substance by 1C (or 1K)....unit is (J/mol*K)
Caloric Theory of Heat Known to be obsolete; the only valid part is that heat is weightless, heat is not a fluid and it is not conserved.
Kinetic Theory of Heat Divides the universe into two parts-system and surrounding A boundary separates the system and the surroundings from each other and can be tangible or imaginary
System The substances involved in the chemical and physical changes under investigation
Surroundings Everything not included in the system, the rest of the universe
First law of thermodynamics Law of conservation of energy, energy is neither created nor destroyed in chemical reactions and physical changes; the energy of the universe does not change
Internal energy Also known as the energy of the system, is the sum of the kinetic and potential energies of the particles
Second law of thermodynamics In spontaneous changes the universe tends towards a state of greater disorder
Entropy (S) The measure of the disorder in a system
Entropy of Reaction (^S) The difference between the sum of the entropies of the products and the sum of the entropies of the reactants.
Third law of thermodynamics The entropy of a pure, perfect, crystallin solid at 0 K is zero
Free energy change (^G) Gibbs free energy, a reliable indicator of spontaneity of a physical process or chemical reaction; it does not tell us how quickly the process occurs
Kinetics Depend on the path (non-state functions); contain the equations-> general rate law, differential rate law and integrated rate laws
Reaction rate The change in concentration of a reactant or product with time
Differential rate law Expresses the rate of a reaction in terms of changes in the concentration of one or more reactants, over a specific time; Rate=k[A][B][C]
Integrated rate law Describes the rate of a reaction in terms of the initial concentration, and the measured concentration of one or more reactants after a given amount of time
Zeroth-order reaction Reaction whose rate is independent of concentration (the change in rate is not affected by the change of reaction)
First-order reaction Reaction rate is directly proportional to the concentration of one of the reactants; these are very common
Second-order reaction 1.Reaction rate is proportional to the square of the concentration of the reactant and has the from 2A->products 2.Reaction rate that is proportional to the product of the concentrations of two reactants and has the form A+B->products
Arrhenius equation An equation with relationship among temperature(T), activation energy(Ea) and specific rate constant(k)
Solvent effects The nature of the solvent can affect the reaction rates of solute particles
Catalyst Increases rate, no matter what by lowering the activation energy and taking different paths; it is not used up in a reaction and is always regenerated; they are often solids (enzymes)
Homogenous catalysts Catalyst exist in the same phase as the reactant
Heterogenous catalysts Catalyst exist in different phase of reactant
Enzymes Are catalysts that occur naturally in living organisms and are almost all protein molecules with typical molecular masses of 20,000-100,000 amu....they are very specific
Substrate Another word for reactant-enzyme
Inhibitor Block activity of enzyme or slow down activity of enzyme
Heat of formation reaction (^Hrxn = ^Hf) 1.must have one product produced 2.must have one mole of this product 3.this product must be made from elements on the reactant side 4.these elements must be in the correct phase at 25C
Created by: ansecaballero