KINETICS

Question 1

what is the rate of reaction? (1)

Answer 1

the speed at which a chemical reaction takes place, the units are mol dm-3 s-1

Question 2

how can we calculate the rate of reaction? (1)

Answer 2

rate of reaction = change in the amount of products-reactants / time

Question 3

what occurs during a reaction? (1)

Answer 3

reactants are used up and changed into products, this means that as the reaction proceeds the concentration of the reactants decreases and the concentration of the products increases

Question 4

what factor must be kept constant to ensure non erroneous results? (1)

Answer 4

temperature should be kept constant as a change in temperature can effect the rate of reaction.

Question 5

how can the rate of reaction be found? (2)

Answer 5

-measuring the decrease of the concentration of a reactant over time
-measuring the increase of the concentration of a product over time

Question 6

how can rate equations be determined? (1)

Answer 6

rate equations can only be determined experimentally and cannot be found from stoichiometric equations

Question 7

what are the types of order of reaction? (3)

Answer 7

order 0
order 1
order 2

Question 8

when can a catalyst appear in a rate equation? (3)

Answer 8

-it must have a measurable and quantifiable effect on the rate of reaction
-the catalyst must be homogenous
-if a chemical appears in the rate equation that is not a reactant it is a catalyst

Question 9

what does the order of reaction show? (1)

Answer 9

shows how the concentration of the reactant affects the rate of reaction.

Question 10

when does a reactant have an order of 0? (1)

Answer 10

this means that it has no effect on the rate of reaction and therefore is not included in the rate equation at all.

Question 11

when does a reactant have an order of 1? (1)

Answer 11

the rate is directly proportional to the concentration of the reactant

Question 12

when does a reactant have an order of 2? (1)

Answer 12

the rate is directly proportional to the square of the concentration of the reactant.

Question 13

what is the overall order of reaction equation? (1)

Answer 13

the overall order of reaction is the sum of the reactants in a rate equation.

Question 14

what is the half-life? (1)

Answer 14

the time taken for the concentration of the limiting reactant to become half of its initial value.

Question 15

what is a zero order graph? (3)

Answer 15

the concentration of the reactant is inversely proportional to the time, this means that the concentration of the reactant decreases with increasing time (the graph is a straight time going down)

Question 16

what is a first order graph? (2)

Answer 16

the concentration of the reactant decreases with time - the graph is a curve going downwards and eventually plateaus

Question 17

what is a second order graph? (2)

Answer 17

the concentration of the reactant decreases more steeply with time (the graph is a steeper curve going downwards)

Question 18

what is the rate of reaction graph for a zero order reactant? (3)

Answer 18

the reaction rate does not depend on the concentration of the reactant, the rate of reaction therefore remains constant (the graph is a horizontal line)

Question 19

what is the rate of reaction graph for a first order reactant? (2)

Answer 19

the rate is directly proportional to the concentration of the reactant - the graph is a straight line

Question 20

what is the rate of reaction graph for a second order reactant? (2)

Answer 20

the rate is directly proportional to the square of the concentration of the reactant - the graph is a curved line