Chemistry 2b

Question 1

What is electrolysis?

Answer 1

To split something up with electricity.

Question 2

What is the limerick that tells you whether the change of electrons is oxidisation or reduction.

Answer 2

OILRIG:
Oxidsation
Is 
Loss
Reduction
Is 
Gain

Question 3

What state must the electrolyte be to be electrolysed?

Answer 3

Liquid.

Question 4

In the electrolysis of lead bromide, which electrode do the lead ions go to, what happens there are are they oxidised or reduced?

Answer 4

The positive lead ions go to the cathode (negative electrode) and gain electrons. They are reduced.

Question 5

How is electrolysis used to extract aluminium?

Answer 5

As aluminium has a very high boiling point (2000 degrees), cryolite (an aluminium ore) is added, bringing the temperature down to 900 degrees. Aluminium forms at the negative electrode. See page 71 of the chemistry revision guide.

Question 6

What is electroplating?

Answer 6

This involves dipping an object into molten metal and using it as an electrode in order to plate it with metal.

Question 7

What is formed when we react an acid with a metal?

Answer 7

A salt and hydrogen.

Question 8

What type of salt is produced with the following acids:

a) Hydrochloric?
b) Sulphuric?
c) Nitric?

Answer 8

a) Chloride salts
b) Sulphate salts
c) Nitrate salts.

Question 9

How is fertiliser made from ammonia?

Answer 9

It’s neutralised (with nitric acid)

Question 10

What is the name given to a reaction that takes in energy?

Answer 10

Endothermic.

Question 11

Can reversible reactions be both exothermic and endothermic?

Answer 11

Yes

Question 12

What is represented by he pH scale?

Answer 12

How acidic/alkaline a chemical is.

Question 13

Is pH 8 acidic or alkaline?

Answer 13

Weak alkaline.

Question 14

What is an indicator?

Answer 14

A substance that changes colour due to a change in pH.

e.g. Phenolphthalein

Question 15

What can be used to neutralise an acid?

Answer 15

A base/alkali

Question 16

What is meant by the state symbol (aq)?

Answer 16

Aqueous - Dissolved in water.

Question 17

What 4 things affect the rate of reaction?

Answer 17

• Temperature
• The concentration
• Surface area of reactants
• Whether a catalyst has been used.

Question 18

Why does an increase in temperature increase the rate of reaction?

Answer 18

The particles have more energy, meaning that they collide at faster speeds, making the activation energy easier to achieve.

Question 19

What is activation energy?

Answer 19

The minimum amount of energy needed for a reaction to be carried out when two particles collide.

Question 20

Why is the rate of reaction increased if we increase the surface area of the reactants?

Answer 20

There is more chance of particle collision, speeding the reaction.

Question 21

What is a catalyst?

Answer 21

A substance that speeds up a reaction by lowering the activation energy by providing an alternative route. They are not used up or changed in the reaction.

Question 22

Why does an increase in concentration lead to an increase in the RofR?

Answer 22

There are more particles to collide with each other, so more collisions occur.

Question 23

What equation is used to calculate the rate of reaction?

Answer 23

Products formed/Reactants used divided by the time taken.

Question 24

How is the rate of reaction measured where a precipitate will be formed?

Answer 24

Observe an ‘x’ through the solution in a conical flask, time how long it takes for said ‘x’ to disappear.

Question 25

How is the rate of reaction measured where a gas is given off?

Answer 25

1 - Measure a change in mass.

2 - Measure the volume of gas given off using a gas syringe.