Unit 2.2 - Acids, Bases and Salts

Question 1

Which particular ions can be found in acids and alkalis?

Answer 1

Acids contain Hydrogen (H+) ions, alkalis contain Hydroxide (OH-) ions.

Question 2

What is the general equation for ACID + METAL?

Answer 2

Acid + Metal -> Metal Salt (Solution) + Hydrogen

Question 3

What is the general equation for ACID + METAL CARBONATE?

Answer 3

Acid + Metal Carbonate -> Metal Salt (Solution) + Carbon Dioxide + Water

Question 4

What is the general equation for ACID + METAL OXIDE?

Answer 4

Acid + Metal Oxide -> Metal Salt (Solution) + Water

Question 5

What is the general equation for ACID + METAL HYDROXIDE?

Answer 5

Acid + Metal Hydroxide -> Metal Salt (Solution) + Water

Question 6

Are oxides and hydroxides more likely to be an insoluble base or an alkali?

Answer 6

Many oxides are bases, while most hydroxides are alkalis.

Question 7

Give the general ion equation for a neutralisation reaction between an acid and a hydroxide.

Answer 7

(H+) + (OH-) -> H20

Question 8

What type of reaction is a neutralisation reaction in terms of energy/temperature before and after?

Answer 8

Exothermic (gives of heat/energy).

Question 9

What would be observed in a reaction between an acid and a metal carbonate?

Answer 9

Effervescence (fizzing) as bubbles of CO2 are produced.

Question 10

Explain the difference between strong and weak acids.

Answer 10

Strong acids dissociate fully in water to produce the maximum number of H+ ions. Weak acids (e.g. Ethanoic Acid) do not dissociate fully. This means the pH values of strong acids are lower, they have a faster rate of reaction, and their reactions have a greater temperature rise.

Question 11

Describe the process of preparing crystals of a soluble salt from the reaction of a metal/carbonate/base and an acid.

Answer 11

• Add excess base to use up all the acid
• Filter the mixture to remove the excess base
• Evaporate the water to leave behind solid salt crystals

Question 12

What reaction is a test for acidic substances and what is the observation?

Answer 12

Reaction with a carbonate - effervescence (as CO2 is produced).

Question 13

When preparing crystals of a salt from a reaction between an acid and a metal/carbonate/base, what affects the size of the crystals?

Answer 13

If the pure solution is heated to evaporate some of the water, the crystals will be smaller. If it is left for longer (without heating), they will be larger.

Question 14

Describe the test for the presence of SO4^2- ions and describe the positive result.

Answer 14

When barium chloride is added to a solution containing sulphate ions, a white precipitate is formed.

Question 15

What are the salts formed by reactions involving ethanoic acid called?

Answer 15

Ethanoates e.g. sodium ethanoate.