chem exam 2

Question 1

what effect reaction rates

Answer 1

temperature
catalysts
concentration of reactants
state/type of reactants

Question 2

what is a half life

Answer 2

the amount of time needed to reduce a substance by 50%

Question 3

how do the orders relate to half lives

Answer 3

0th order- half life decreases as concentration decreases
1st order- half life is constant
2nd order- hlaf life time increases as concentration decreases

Question 4

what is little k

Answer 4

the rate law constant

Question 5

what is the rate law general equation

Answer 5

rate law = k[a]^x[b]^y

Question 6

what is collision theory

Answer 6

it explains why different reactions occur at different rates

Question 7

what equation is used in collision theory

Answer 7

arrhenius - k=Ae^(-Ea/RT)

Question 8

what does each letter stand for in the arrhenius equation

Answer 8

A- orentation
-Ea= activation energy
T- temperature
R- gas constant

Question 9

what are the parts of the collision theory

Answer 9

-molecules must collide
- need enough energy
-orientation

Question 10

how does A describe the orientation

Answer 10

the smaller a= the “pickier” reaction

Question 11

explain molecules colliding in collision theory

Answer 11

if concentration increases then collisions increase then reaction increases

Question 12

explain energy in collision theory

Answer 12

-if activation energy is higher then the rate decreases
-if temp increases the the rate increases

Question 13

if a reaction is single step, how should the orders look

Answer 13

the orders should match the stoichiometric coefficient

Question 14

what is an intermediate

Answer 14

a species that is produced in one step and consumed in another
- doesnt appear in overall reaction

Question 15

how do you determine the higher order

Answer 15

by the slowest step

Question 16

for an elementary step what do the reaction orders equal and proved an example

Answer 16

they equal the stiochiometric coefficients
ex: a->b = k[a]
ex: b+2c-> d+e = k[b][c]^2

Question 17

what is physical equilibrium

Answer 17

forward and reverse reactions happen at the same rate but there is no chemical reaction
ex: phase changes and solubility

Question 18

chemical equilibrium

Answer 18

forward and reverse reactions are equal and a chemical change is occuring

Question 19

do equilibrium concentrations have to be the same

Answer 19

no

Question 20

what is K

Answer 20

equilibrium constant

Question 21

what is the general equation for K

Answer 21

products
_________
Reactants

Question 22

how do you know if a reaction has more products or reactants

Answer 22

if K>1 then more products
if K<1 then more reactants

Question 23

what is Kf

Answer 23

formation constant

Question 24

what is Kd

Answer 24

dissociation constant

Question 25

how are Kf and Kd related

Answer 25

Kd is the inverse of Kf

Question 26

how do Q and K relate

Answer 26

if Q=K then products and reactants stay the same
if Q>k then there are too many products and reaction will shift to reactants
if Q<K then there are too many reactants and will shift to make more products

Question 27

how does adding heat to the reactants effect equilibrium

Answer 27

it will shift to the right and is endothermic