18.3- DETERMINING THE RATE EQUATION

Question 1

What does the rate expression tell you?

Answer 1

how rate of reaction depends on concentration of species involved

Question 2

What does the rate expression only include?

Answer 2

species that affect rate of reaction

Question 3

What is a species zero order?

Answer 3

if rate not affected by conc. of that species

Question 4

If the order is zero for a species, is it included in the rate expression?

Answer 4

no

Question 5

What is the first order of a species?

Answer 5

rate directly proportional to conc. of species

Question 6

What is the second order of a species?

Answer 6

rate proportional to square of conc. of species

Question 7

What is one method of finding the order of a reaction with respect to a particular species?

Answer 7

by plotting graph of rate against conc.

Question 8

How to find reaction rates at different concentrations using a graph?

Answer 8

plot graph of conc. of species against time, and draw tangents at different values of conc of species
gradient of tangents are reaction rates at diff. conc.

Question 9

What can the values of reaction rate from the concentration-time graphs be used to construct?

Answer 9

second graph of rate against concentration

Question 10

What does the rate against conc. graph being a horizontal straight line show?

Answer 10

means rate unaffected by conc. if that species and so order zero

Question 11

What does the rate against conc. graph being a sloping straight line through the origin show?

Answer 11

order is 1

Question 12

What does the rate against conc. graph not being a straight line mean?

Answer 12

order cannot be found directly- could be two
try plotting rate against [species]²
if this is straight line, then order two

Question 13

How do small changes in temperature change reaction rates?

Answer 13

produce large changes in reaction rates

Question 14

What is a rough rule for how temperature affects reaction rates?

Answer 14

for every 10K rise in temp, rate of reaction doubles

Question 15

What dies a larger value of k (rate constant) show?

Answer 15

larger the value of k, faster the reaction

Question 16

How does the value of k change with temp?

Answer 16

value of k increases with temp

Question 17

What is temperature a measure of?

Answer 17

measure of average KE of particles

Question 18

When will particles only reaction together?

Answer 18

if their collisions have enough energy to start bond breaking

Question 19

What is the energy to start bond breaking called?

Answer 19

activation energy

Question 20

As temperature increases, what happens to the number of molecules with enough energy to react?

Answer 20

as temp increases, greater proportion of molecules have enough energy to react