End Of Unit Questions

Question 1

Dilute nitric acid is added to sodium hydroxide solution. What type of reaction happens?

Answer 1

Neutralisation

Question 2

Dilute nitric acid is added to sodium hydroxide solution. Why is an indicator used to show when the reaction is complete?

Answer 2

There is no visible change and it will show when the pH is 7

Question 3

Dilute nitric acid is added to sodium hydroxide solution. Write a word equation for the reaction

Answer 3

Nitric acid + sodium hydroxide –> sodium nitrate + water

Question 4

Describe the main steps to make zinc sulfate crystals from zinc oxide and dilute sulphuric acid

Answer 4

Add zinc oxide, little by little, to dilute sulfuric acid until there is an excess, evaporate the water to leave the excess, leave the salt to cool and crystallise

Question 5

Describe how you could make some insoluble lead sulfate from solutions of lead nitrate and sodium sulfate

Answer 5

1. Mix the solution
2. Filter the mixture or leave to settle and decant
3. Separate the precipitate
4. Wash it with distiller water and dry

Question 6

Why are some items of jewellery made of gold plated nickel?

Answer 6

They are less expensive than pure gold and also so they don’t corrode

Question 7

Name the products when sodium chloride is electrolysed and give one use for each

Answer 7

• hydrogen, used for margarine manufacturing
• chlorine, used to make bleach
• sodium hydroxide, used to as a cleaning agent

Question 8

Aluminium is manufactured from aluminium oxide, which is inexpensive. Why is manufacturing aluminium an expensive?

Answer 8

It needs larger amounts of electricity as it needs high temps to melt

Question 9

Aluminium is manufactured from aluminium oxide, which is inexpensive. Why is cryolite used in the process to make aluminium?

Answer 9

To lower the melting temperature of the electrolyte

Question 10

Explain as fully as you can what happens at the electrodes when molten sodium chloride is electrolysed

Answer 10

At the negative electrode the sodium ions gain electrons so are reduced to sodium atoms. At the positive electrode the chloride ions lose electrons so are oxidised to chlorine molecules

Question 11

Write half equations for the reactions at the electrodes when magnesium chloride solutions MgCl2(aq) is electrolysed using carbon electrodes.

Answer 11

Positive: 2Cl- –> Cl2 + 2e-
Negative: 2H+ + 2e- –> H2

Question 12

Dilute nitric acid is added to sodium hydroxide solution. What type of substance is sodium hydroxide?

Answer 12

An alkali