Rate and Equilibrium

Question 0

Definition of rate constant

Answer 0

The constant that links the rate of reaction with the concentrations of the reactants raised to the power of the orders in the rate equation

Question 1

Definition of rate of reaction

Answer 1

The change in concentration of a reactant or product per unit time

Question 2

Definition of half-life

Answer 2

The time taken for the concentration of the reactant to reduce by half

Question 3

Definition of rate-determining step

Answer 3

The slowest step in the reaction mechanism of a multi-step reaction

Question 4

The half life of a first-order reaction is…

Answer 4

Independent of the concentration

Question 5

Formula of the rate equation

Answer 5

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

Question 6

What is the effect of temperature change on a rate constant?

Answer 6

-raising the temperature speeds up the rate of most reactions by increasing the constant, k.

Question 7

Expression for Kc

Answer 7

Kc=[products]/[reactants]

Question 8

What is the effect of increasing temperature on the value of Kc for exothermic reactions?

Answer 8

Shifts to the left (endothermic direction)

Question 9

What is the effect of increasing temperature on the value of Kc for endothermic reactions?

Answer 9

Shifts position to the right (endothermic direction)

Question 10

What is the effect of decreasing temperature on the value of Kc for exothermic reactions?

Answer 10

Shifts to the right (exothermic direction)

Question 11

What is the effect of decreasing temperature on the value of Kc for endothermic reactions?

Answer 11

Shifts to the left (exothermic direction)

Question 12

What is Kc unaffected by?

Answer 12

Concentration, pressure and catalysts

Question 13

What is Kc affected by?

Answer 13

Changes in temperature

Question 14

Zero-order concentration-time graph

Answer 14

• Concentration decreases at a constant rate.

- half-life decreases with time

Question 15

First order concentration-time graph

Answer 15

• Concentration halves in equal time intervals.

- half-life is constant

Question 16

Second order concentration-time graph

Answer 16

• concentration decreases rapidly, but the rate of decrease then slows down.
• half-life increases with time

Question 17

Zero order rate-concentration graphs

Answer 17

• Rate is proportional to [A]^0
• The rate is unaffected by changes in concentration.
• As x increases, y stays constant

Question 18

First order rate-concentration graphs

Answer 18

The rate is proportional to [A]^1

-If conc increases by 2 times, the rate does as well.

Question 19

Second order rate-concentration graphs

Answer 19

rate is proportional to [A]^2

• if A increases by 2 times, rate increases by 4
• if A increases by 3 times, the rate increases by 9 times.

Question 20

How to calculate pH from strong acids

Answer 20

pH=-log[acid]

because strong acids fully dissociate so [H+]=[acid]

Question 21

How to calculate pH of weak acids

Answer 21

Use Ka:
-For weak acids, [H+]=[A-] because the acid dissociates to the both ions equally
- Ka=([H+]^2)/[HA]
pH= -log(root(Ka x [HA]))

Question 22

How do we calculate Ka for weak acids?

Answer 22

Ka= [H+][A-]/[HA]

Ka=[H+]^2/[HA]

Question 23

Calculate the pH of strong bases using Kw

Answer 23

Kw=[H+][OH-]=1.00 x10^-14

Gives you pOH or pH
pH=14-pOH