Topic 9 - Reactions Of Acids

1. What is a neutraliser?

A substance that can neutralise an acid only

A substance that can neutralise an alkali only

A substance that can neutralise an acid or an alkali

A neutralizer is a substance that has the ability to neutralize both acids and alkalis. It can react with an acid to form a salt and water, or with an alkali to form a salt and water. This means that a neutralizer can effectively balance the pH levels of both acidic and alkaline solutions, bringing them closer to a neutral pH of 7.

Explanation

A neutralizer is a substance that has the ability to neutralize both acids and alkalis. It can react with an acid to form a salt and water, or with an alkali to form a salt and water. This means that a neutralizer can effectively balance the pH levels of both acidic and alkaline solutions, bringing them closer to a neutral pH of 7.

2. Name the salt produced when sodium carbonate reacts with sulphuric acid.

Sodium carbide

Carbon sulphide

Sodium sulphate

Sodium sulphide

acid + metal carbonate --> salt + water + CO2
Suphuric acid produce salts with the ending sulphate.

Explanation

acid + metal carbonate --> salt + water + CO2
Suphuric acid produce salts with the ending sulphate.

3. Complete the following equation: Magnesium oxide + hydrochloric acid -->

Magnesium chloride + hydrogen

Magnesium chloride + water

Magnesium chloride + water + CO2

metal oxide + acid --> salt + water

Explanation

metal oxide + acid --> salt + water

4. A salt is a substance in which the ___________ ion of the acid has been replaced by a metal (or ammonium) ion.

A salt is formed when the hydrogen ion (H+) of an acid is replaced by a metal or ammonium ion. This replacement results in the formation of a new compound known as a salt. The options "hydrogen," "H+," "Hydrogen," and "H2" all refer to the hydrogen ion present in the acid. Therefore, any of these options can be used to complete the given statement correctly.

Explanation

A salt is formed when the hydrogen ion (H+) of an acid is replaced by a metal or ammonium ion. This replacement results in the formation of a new compound known as a salt. The options "hydrogen," "H+," "Hydrogen," and "H2" all refer to the hydrogen ion present in the acid. Therefore, any of these options can be used to complete the given statement correctly.

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5. When lime is added to acidic soil, the pH will get lower.

True

False

If the soil is pH 4, when lime is added, the soil pH will increase towards pH 7 as the alkaline lime neutralises the acidity in the soil.

Explanation

If the soil is pH 4, when lime is added, the soil pH will increase towards pH 7 as the alkaline lime neutralises the acidity in the soil.

6. Name the gas produced when magnsium reacts with nitric acid

Hydrogen

Carbon dioxide

Nitrogen

Oxygen

(Reactive) metal + acid --> salt + H2

Explanation

(Reactive) metal + acid --> salt + H2

7. How many moles of HCl acid will be used if the volume is 20 cm³ and the concentration is 0.1 mol/l.

0.02

0.002

2

0.0002

n = c x v where v must be in litres, 0.1 x 20/1000 = 0.002 moles of acid

Explanation

n = c x v where v must be in litres, 0.1 x 20/1000 = 0.002 moles of acid

8. What is the average volume of acid used during the following titration.

Rough titre - 25.2 cm³1st titre - 22.3 cm³2nd titre - 22.1 cm³

22.2

23.2

44.4

69.6

Ignore the rough titre - average of 1st and 2nd (22.3 + 22.1 = 44.4 / 2 = 22.2)

Explanation

Ignore the rough titre - average of 1st and 2nd (22.3 + 22.1 = 44.4 / 2 = 22.2)

9. What would be the concentration of magnesium hydroxide solution if 25 cm³ was needed to neutalise the HCl acid (conc 0.1, vol 20 cm³ ).

Hint: You will need to write a balanced equation

0.4 mol/l

0.04 mol/l

0.08 mol/l

0.1 mol/l

Mg(OH)2 + 2HCl --> MgCl2 + 2H2O
2 moles HCl --> 1 mole Mg(OH)2
0.002 moles HCl -> 0.001 moles Mg(OH)2
c = n/v = 0.001/(25/1000) = 0.04 mol/l

Explanation

Mg(OH)2 + 2HCl --> MgCl2 + 2H2O
2 moles HCl --> 1 mole Mg(OH)2
0.002 moles HCl -> 0.001 moles Mg(OH)2
c = n/v = 0.001/(25/1000) = 0.04 mol/l

10. Name the type of reaction when sodium carbonate solution is added to copper (II) sulphate solution. (You may wish to use page 5 of the data booklet).

Neutralisation

Addition

Precipitation

Oxidation

Na2CO3(aq) + CuSO4(aq) --> CuCO3(s) + Na2SO4(aq)

Explanation

Na2CO3(aq) + CuSO4(aq) --> CuCO3(s) + Na2SO4(aq)

11. Which box or boxes are examples of neutralisation.

Adding lime to acidic soil

Using toothpaste to neutralise mouth alkalinity

Using lemon juice to neutralise bee stings

Using lemon juice to neutralise wasp stings.

lime (calcium hydroxide - not the fruit) is an alkali, so will neutralise acidic soil. Lemon juice is acidic so will only neutralise alkaline wasp stings, (bee stings as they are acidic). The pH of the mouth is acidic not alkaline.

Explanation

lime (calcium hydroxide - not the fruit) is an alkali, so will neutralise acidic soil. Lemon juice is acidic so will only neutralise alkaline wasp stings, (bee stings as they are acidic). The pH of the mouth is acidic not alkaline.

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