Chapter y- Rates of Reaction

Question 1

What is the rate equation?

Answer 1

rate = k [A]^n [B]^m
k: rate constant/ units vary
[A], [B]: conc. of reactants A and B/ mol/dm^3
n,m: order of reaction with respect to their species

Question 1

What do the orders m and n show and how is the total order of the reaction found?

Answer 1

The order of the reaction with respect to that species, telling you how a reactant’s conc. will affect the rate of reaction.
Total order= sum of orders of species

Question 2

What is the impact of the concentration of the reactant and graph of rate v conc. for order 0?

Answer 2

Concentration of species has no effect on rate
Graph is a horizontal line

Question 3

What is the impact of the concentration of the reactant and graph of rate v conc. for order 1?

Answer 3

Concentration of species is directly proportional to rate
Graph is a straight line passing through origin

Question 4

What is the impact of the concentration of the reactant and graph of rate v conc. for order 2?

Answer 4

Rate is proportional to concentration squared
Graph is like a quadratic

Question 5

What is the rate constant and when is it constant?

Answer 5

A constant that relates the rate of a chemical reaction at a given temperature to the product of the concentrations of reactants.
Constant at constant temperature

Question 6

What does the Arrhenius equation show?

Answer 6

How k varies with temperature, related exponentially

Question 7

What is the Arrhenius equation?

Answer 7

k = Ae^ -Ea/RT
k: rate constant
A: pre-exponential factor
Ea: activation energy/ kJ/mol
R: gas constant
T: temperature/ K

Question 8

What is the rate determining step and how is it linked to the rate equation?

Answer 8

The slowest step in a reaction that determines the rate of the overall reaction
The species’ orders in the rate equation are the number of molecules of the species involved up to and including the rate determining step in the reaction

Question 9

What is the initial rate method for measuring rates and finding orders of species?

Answer 9

RP 7a: -multiple experiments in which all variables other than [X] you investigate are kept constant
-Record [X], time and rate for each reaction
-Plot rate against [X], observe graph for relationship

Question 10

What is the continuous method for measuring rates and finding orders of species?

Answer 10

RP 7b: -multiple experiments in which all variables other than [X] you investigate are kept constant
-measure volume of gas produced at regular time intervals
-plot graph of volume against time, using a tangent at a point to find the rate
-repeat with different [X] to find multiple rates and plot a graph of rate against [X], observe graph