chem ch14/15 exam

4 factors affecting rate

• physical state

• Reactant temp

• Reactant concentration

• Catalyst

As rate of rxn increases, surface area…?

Increases

As concentration increases, rxn rate…?

Increases

As temperature increases, rxn rate…?

Increases

When a catalyst is present rxn rate…?

Increases

What is the rate law

rate=k[A]^m[B]^n

What are the differences in rate law graphs

0th order - most downward

First order - sloped downwards

Second order - sloped upwards

If the activation energy is high, rxn rate…?

Decreases

What is half life

0.693/k. (t1/2) Time it takes for reactant to be half its initial concentration

What is the rate determining step

Slowest step in a reaction

How do catalysts effect rxn rate?

Lowers activation energy and increase rxn rate

What is equilibrium?

Opposing chemical rxn’s (equal rates) reversable

Rate formula

Rate = k [A]^m[B]^n

Rate of appearance/disappearance

-[A]/c(t) = [D]/c(t)

Half life eq

.693/k

1st order concentration over time

ln[R],t, = -kt + ln[R],0,

Arrhenius eq

ln k = (-Ea/R)(1/T) + ln A

Arrhenius eq over T

ln(K1/K2) = Ea/R (1/T2 - 1/T1)

Kc eq and Kp eq

Kc = [D]^d[C]^c/[B]^b[A]^a

Kp = (PD)^d?(PC)^c/(PB)^b(PA)^a

Conversion between Kp and Kc

Kp = Kc (RT)

How does rxn expression change if the rxn is reversed

K = 1/K1

How does rxn expression change when the rxn is multiplied

K = K^n

How does rxn expression change if rxn is multiple steps

K3 =(K1)(K2)

Le Chat equilibrium shift bc of temperature

Endothermic - R-P+heat

Exothermic - R+heat-P

Change in K due to change in Temp

Endothermic = directly proportional (R side)

Exothermic = indirectly proportional (P side)

Catalyst effect on equilibrium

Reaches equilibrium faster