Topic 7 - Rates Of Reaction

Question 1

Equation for the rate of reaction?

Answer 1

Rate of reaction = amount used or product formed / time

Question 2

Explain the precipitation experiment ?

Answer 2

Mix reactant solutions (which produce a precipitate ) and under the beaker place a piece of paper with a mark. After adding the substances together measure how long it takes for the mark to disappear - although test is subjective beacause of human error.

Question 3

Describe the step of the change in mass experiment ?

Answer 3

We can measure rate of reaction using a mass balance. The quicker the reading on the balance drops the faster the reaction is. We know the reaction has finished when the balance stops changing.

Question 4

Describe the volume of gas given off experiment…

Answer 4

This involves using a gas syringe to measure the volume given off. The more gas is given off during a set time interval the faster the reaction. We can tell it’s finished when no more gas is being produced.

Question 5

How to work out the gradient of a curvy graph?

Answer 5

Change in y/change in x

Question 6

Define a successful collision.

Answer 6

Collision with enough energy to react.

Question 7

Describe an experiment to check how the surface area affects the rate of reaction.

Answer 7

Using a gas syringe take readings of gas produced by marble chips With HCl and CO2. Repeat the experiment with the same volume of acid , mass of chips but crunch them up more . Compare

Question 8

Does the concentration of acid affects the rate and in what way ?

Answer 8

Higher concentration means higher rate. So yes

Question 9

Describe how you could investigate how surface area of calcium carbonate affects the rate of reaction? Between calcium carbonate and hydrochloric acid..

Answer 9

Place a volume of acid with knows concentration in a conical flask. Add a known mass of calcium carbonate and join a gas syringe to the beaker. Take readings at regular time intervals. Repeat the experiment with the same volume,concentration and mass but increase surface area.

Question 10

How can surface area be increased?

Answer 10

Cutting the object or elements in half.

Question 11

How does the temperature effect rate of reaction. Why?

Answer 11

Higher temperature will mean faster rate of reaction. This is beacause particles move after so there is more frequent collisions and so successful collisions.

Question 12

What does the rate of reaction depend on ?

Answer 12

Collision frequency and energy transferred during a collision.

Question 13

Factors affecting rate of reaction ?

Answer 13

Temperature
Concentration or pressure(only for gases)
Surface area

Question 14

How does the concentration or pressure increase rate of reaction ?

Answer 14

Higher concentration means there is more particles, therefore there is a higher chance for a collision

Question 15

How does surface area increase rate of reaction?

Answer 15

More area means there is more space for particles to collide against. This means frequency of collisions will increase.

Question 16

How does the temperature increase rate of reaction?

Answer 16

Particles move faster and so there is more collisions. Also this means there will be more energy per collisions since they’re moving faster .

Question 17

Function of a catalyst?

Answer 17

Increases rate without being chemically changed or used up. They decrease the activation energy necessary.

Question 18

Provide an example for a catalyst and explain it…

Answer 18

ENZYMES! They’re biological catalysts that speed up the reactions in living cells. Like respiration,photosynthesis or protein synthesis.

Question 19

What is an exothermic reaction?

Answer 19

A reaction that gives out energy to the surroundings, usually as heat. This can be checked as temperature of surrounding should increase.

Question 20

What is an endothermic reaction?

Answer 20

A reaction that take in energy from surroundings.

Question 21

What labels need to be shown on a graph for exothermic reaction?

Answer 21

Activation energy, energy released ,products and reactants.

Question 22

What labels need to be shown on a graph for endothermic reaction ?

Answer 22

Activation energy,energy absorbed,react and and products.

Question 23

Equation for overall energy change ?

Answer 23

Energy to break bonds - energy to make bonds

Question 24

What does a negative answer in the bond calculations mean?

Answer 24

Means an exothermic so a loss of energy.

Question 25

What does a positive answer in the bond calculation mean?

Answer 25

It means an endothermic so energy is taken in.