Rates Of Reaction

Question 1

What are 5 experimental methods of obtaining rate data?

Answer 1

• Mass change
• Volume of gas evolved
• Titration
• Colorimetry
• pH meter

Question 2

How is rate calculated on a graph?

Answer 2

• Gradient of the line change in y/change in x
• Draw a tangent where curve meets specific point if curved

Question 3

Rate reaction equation

Answer 3

Rate = k[A]^a [B]^b

Question 4

What are units for rate?

Answer 4

mol-1dm-3s-1

Question 5

What does the orders of reaction tell us?

Answer 5

Tells us how the concentration of the substance affects the rate

Question 6

Orders of reaction

Answer 6

Zero - no change
First- Rate Doubles
Second- Rate quadruples

Question 7

What happens to the rate constant if you increase the temperature

Answer 7

The particles have more kinetic energy and they collide more often, this increases the rate. The larger the value of ‘k’ the faster the rate of reaction.

Question 8

Different between rate-concentration graph and concentration time graph

Answer 8

• R-C are created by knowing the rate.
• The rate is found by taking the gradient at various points on a C-T graph

Question 9

What is half life?

Answer 9

Half life is the time it takes for half of the reactant to be used up

Question 10

What does it mean for the rate constant if there is a constant half life?

Answer 10

It is 1st order

Question 11

Half life equation

Answer 11

• k = ln (2) / t1/2
• t1/2 = ln (2)/ k

Question 12

How to word comparing experiment questions

Answer 12

Comparing Experiments X and Y, [A] is (x) order with respect to [A]

Question 13

Rate determining step

Answer 13

The slowest step in a multi-step reaction (e.g putting a cake in the oven)

Question 14

What does the orders indicate about the rate determining step?

Answer 14

• The orders indicate the number of molecules of each substance involved

Question 15

What does the arrehnius equation tell us?

Answer 15

Shows how k and temperature are related exponentially and links activated energy

Question 16

What happens to the rate constant as the activation energy gets smaller

Answer 16

The rate constant gets bigger because the rate of reaction increases. More particles have enough energy to react when they collide.

Question 17

Arrhenius plot to find out activation energy and Arrhenius constant

Answer 17

LnK = -Ea/R x 1/T + lnA
y = mx + c

Question 18

What do we assume about the rate of reaction in clock experiments?

Answer 18

The rate of reaction remains constant so the average rate is same as the initial rate

Question 19

What do we assume about the temperature in clock experiments?

Answer 19

Remains consatnt

Question 20

What do we assume about the concentration in clock experiments?

Answer 20

The concentration of reactant doesn’t change significantly during the time period of the reaction

Question 21

What do we assume about the reaction in clock experiments?

Answer 21

Reaction has not proceeded too far when the end point is seen

Question 22

What does the reactants that appear in rate equation tell us about the rate determining step?

Answer 22

Reactants that appear in the rate equation affect the rate of reaction, therefore these reactants must appear in the rate determining step.