exam 2

Question 1

activation energy Ea

Answer 1

difference in energy between the reactants and the activated complex

Question 2

Effective collisions

Answer 2

Collisions that result in a reaction

Question 3

Transition State

Answer 3

temporary, high energy, unstable configuration that occurs during chem rxns

Question 4

Rate constant

Answer 4

proportionality constant in a chemical reaction’s rate law

Question 5

Rate law

Answer 5

equation in chemistry that shows how the rate of a chemical reaction depends on the concentration of its reactants

Rate = k[A]m [B]n

Question 6

Reaction order

Answer 6

describes how a chemical reaction’s rate depends on the concentration

m+n

Question 7

Half-life

Answer 7

length of time it takes for the concentration of the reactant to fall to ½ its initial value

t½

Question 8

Reaction mechanism

Answer 8

the step-by-step sequence of elementary reactions by which a chemical reaction occurs

Question 9

Elementary reactions

Answer 9

Each step in a reaction mechanism

Question 10

Intermediate

Answer 10

a temporary molecular species formed and consumed during a chemical reaction

Question 11

Molecularity

Answer 11

the number of reactant molecules or ions that participate in a single elementary step of a chemical reaction

Question 12

Rate-Determining Step

Answer 12

slowest step

Question 13

Catalyst

Answer 13

speeds up a chem rxn without being consumed

Question 14

Homogeneous catalysis

Answer 14

in the same phase as the reactants

Question 15

Heterogeneous catalysis

Answer 15

in a diff phase than the reactants

Question 16

Enzyme

Answer 16

Protein molecules that catalyze biological reactions

Question 17

4 main factors that can increase the rate of a reaction

Answer 17

higher temp
inc reactant conc
surface area/orientation
presence of a catalyst

Question 18

reversible process

Answer 18

A process that reverses direction upon an infinitesimally small change in some property.

Question 19

when is a reaction reversible

Answer 19

not all sp are in the same phase (heterogeneous)

Question 20

Dynamic chemical equilibrium

Answer 20

rate of forward rxn=rate of reversible rxn

Question 21

Reaction quotient

Answer 21

The concentration ratio of the products (raised to the power of their coefficients) to the reactants (raised to the power of their coefficients)

Question 22

Law of mass action

Answer 22

The relationship between the balanced chemical equation and the expression of the equilibrium constant

Question 23

Equilibrium constant

Answer 23

value that expresses ratio of products and reactants

Question 24

Equilibrium expression

Answer 24

ratio of products to reactants

Question 25

LeChatelier’s Principle

Answer 25

when a stress is applied to a system at equilibrium, the system, will respond by shifting in the direction that minimizes the effect of the stress

Question 26

what is equal when a chemical reaction is in equilibrium

Answer 26

rates of the forward and reverse reactions

Question 27

qc is < kc

Answer 27

reaction has a higher concentration of reactants than products and will shift to the right (favors reactants)

Question 28

qc is > kc

Answer 28

the reaction has a higher concentration of products than reactants and will shift left (favors products)

Question 29

heterogeneous equilibrium

Answer 29

not all sp in rxn are in same phase

Question 30

homogenous equilibrium

Answer 30

all sp in rxn are in same phase

Question 31

which way does rxn shift if pressure is added

Answer 31

away from side with more moles of gas

Question 32

which way does rxn shift if pressure is added

Answer 32

towards side with more moles of gas

Question 33

what happens to Kc in an exothermic rxn when temp inc

Answer 33

Kc dec

Question 34

what happens to Kc in an endothermic rxn when temp inc

Answer 34

Kc inc

Question 35

what happens to a rxn in equilibrium when an inert sp is added

Answer 35

nothing

Question 36

what happens to a rxn in equilibrium when a catalyst is added

Answer 36

doesn't effect position of equilibrium

Question 37

Does temperature affect the value of the equilibrium constant (Kc)?

Answer 37

yes it effects it differently based on if its endothermic or exothermic