4.4.2 Reactions of acids

Question 1

What is the general equation for a reaction between metals and
acids? What type of reaction is this?

Answer 1

Metal + acid → salt + hydrogen
Redox reaction, also a displacement reaction

Question 2

Which metals in the reactivity series will react with acid?

Answer 2

Those above hydrogen

Question 3

What is the general equation for a neutralisation reaction?

Answer 3

Base + acid → salt + water

Question 4

What is the general equation for the reaction between metal
carbonate and acid?

Answer 4

Metal carbonate + acid → salt + water + carbon dioxide

Question 5

What is the general equation for the reaction between metal oxides
and acids?

Answer 5

Metal oxide + acid → a salt + water

Question 6

What is a redox reaction?

Answer 6

A reaction where both oxidation and reduction occurs

Question 7

How is a soluble salt formed?

Answer 7

a) React the excess acid with some insoluble chemical (e.g. metal oxide)
b) Filter off the leftovers
c) Crystallise the product

Question 8

What do acids and alkalis produce in aqueous solutions?

Answer 8

Acids produce hydrogen ions, alkalis produce hydroxide ions

Question 9

What are bases, acids and alkalis?

Answer 9

Bases are compounds that neutralise acids, acids produce hydrogen ions in aqueous solutions, alkalis are soluble bases - produce hydroxide ions in aqueous solutions

Question 10

What is the pH scale and what does a pH of 7 show?

Answer 10

The measure of acidity/alkalinity of a solution; neutral solution

Question 11

State the general equation for a neutralisation reaction in a short, ionic form.

Answer 11

H+ + OH− → H2O

Question 12

What is a strong acid? What is a weak acid?

Answer 12

Strong acid is completely ionised in aqueous solution; weak acid is only partially ionised in aqueous solution

Question 13

What happens to pH as concentration of H+ increases?

Answer 13

The pH decreases

Question 14

What is a concentrated acid and what is a dilute acid? Is this the same as a strong and weak acid?

Answer 14

• Concentrated acid has more moles of acid per unit volume than dilute (dilute refers to solutions of low concentrations)
• It is not the same - concentration is not the same thing as strength of an acid.
• Strength refers to whether the acid is completely ionised in water (strong) or
  only partially (weak).

Question 15

As the pH is decreased by one unit, what change is seen in the
hydrogen ion concentration?

Answer 15

Increases by a factor of 10

Question 16

Name the following salts: LiNO3, K2CO3, MgBr2, BaSO4

Answer 16

Lithium nitrate Potassium carbonate Magnesium bromide Barium sulfate