5.1.1 - How Fast

Question 1

What is the reaction rate?

Answer 1

The change in the amount of reactants or products per unit time.

Question 2

What does the order of reaction tell you?

Answer 2

How the reactant’s concentration affects the rate.

Question 3

If the order is 0 what will happen to the rate if the concentration of the reactant is doubled?

Answer 3

Rate stays the same.

Question 4

If the order is 1 what will happen to the rate if the concentration of the reactant is doubled?

Answer 4

Rate also doubles.

Question 5

If the order is 2 what will happen to the rate if the concentration of the reactant is doubled?

Answer 5

The rate quadruples.

Question 6

Rate =

Answer 6

k[A]^m [B]^n

Question 7

What is k, and what does it mean if it is bigger?

Answer 7

k is the rate constant and the bigger it is, the faster the reaction.

Question 8

What are m and n in the rate equation?

Answer 8

The orders of reaction with respect to reactant A and reactant B.

Question 9

On a concentration-time graph what does 0 order look like?

Answer 9

Straight line downwards (negative gradient) \

Question 10

On a concentration-time graph what does 1st order look like?

Answer 10

Curve downwards like a curly l.

Question 11

What is the half life of a reaction?

Answer 11

The time it takes for half of the reactants to be used up.

Question 12

What can you use the half life to calculate?

Answer 12

The order of the reactant, and the rate constant k.

Question 13

What happens to the half life in for 0 order?

Answer 13

The half life decreases.

Question 14

What happens to the half life for 1st order?

Answer 14

Same length.

Question 15

What happens to half life in a second order reaction?

Answer 15

Increases.

Question 16

What is the equation for calculating k using the half life? (Only 1st order)

Answer 16

k = In2 / half life

Question 17

What is the rate concentration graph for 0 order?

Answer 17

Straight horizontal line.

Question 18

What is the rate concentration graph for 1st order?

Answer 18

Straight line through origin, directly proportional.

Question 19

What is the rate concentration graph for 2nd order?

Answer 19

Curve upwards.

Question 20

What 4 ways can you measure the rate of reaction?

Answer 20

• measure the volume of gas evolved.
• measure the loss in mass of a gas evolved.
• use colorimetry to measure the colour change of a reaction.
• measure the pH change of a reaction.

Question 21

What is the rate determining step?

Answer 21

The slowest step in a reaction.

Question 22

How do you know what reactants are in the rds?

Answer 22

They are in the rate equation.

Question 23

How many moles of each reactant is in the rate equation?

Answer 23

You look at the order and that tells you how many moles of each of the reactant.

Question 24

What are intermediates?

Answer 24

Not shown in the overall equation as they are created and used up.

Question 25

What must occur to particles in order for a reaction to take place?

Answer 25

They must collide with energy equal to or above the activation energy and they must collide with the right orientation.

Question 26

What happens to the rate constant when the temperature increases?

Answer 26

It also increases.

Question 27

In the Arrhenius equation what is activation energy measured in?

Answer 27

J mol-1

Question 28

In the Arrhenius equation what is temperature measured in and how do you calculate this?

Answer 28

Kelvin (+273)

Question 29

When you log the Arrhenius equation what graph do you plot? What is the gradient and what is the y intercept?

Answer 29

ln against 1/T. -Ea/R. InA