Acid bases theory

Question 1

State which substance turns yellow when an alkali is added.

Answer 1

Methyl orange

Question 2

Complete the word equation for the reaction of magnesium oxide with hydrochloric acid.

Answer 2

Magnesium chloride + water

Question 3

Which of the following compounds is insoluble in water: magnesium carbonate, magnesium chloride, magnesium nitrate, magnesium sulfate?

Answer 3

Magnesium carbonate

Question 4

Complete the word equation: sulfuric acid + sodium carbonate →

Answer 4

Sodium sulfate + carbon dioxide + water

Question 5

State the colour of thymolphthalein indicator in dilute sulfuric acid.

Answer 5

Colourless

Question 6

Complete the word equation for the reaction of dilute sulfuric acid with sodium carbonate.

Answer 6

Sodium sulfate + carbon dioxide + water

Question 7

Complete the word equation for the reaction of ethanoic acid with magnesium.

Answer 7

Magnesium ethanoate + hydrogen

Question 8

Which pH value is alkaline: pH 1, pH 5, pH 7, or pH 10?

Answer 8

pH10

Question 9

Give the formula of the ion present in all alkaline solutions.

Answer 9

OH⁻

Question 10

Which pH value is alkaline: pH 1, pH 4, pH 7, or pH 13?

Answer 10

pH13

Question 11

Complete the word equation: ammonium chloride + calcium hydroxide →

Answer 11

Ammonia + calcium chloride + water

Question 12

Explain why the reaction CaO + SiO₂ → CaSiO₃ can be described as an acid–base reaction.

Answer 12

Calcium oxide is a basic oxide and silicon dioxide is an acidic oxide, and they react to form calcium silicate (a salt).

Question 13

Define the term base.

Answer 13

A base is a proton acceptor.

Question 14

State what is meant by the term alkali.

Answer 14

A soluble base that produces OH⁻ ions in aqueous solution.

Question 15

State the colour of thymolphthalein in NaOH(aq).

Answer 15

Blue

Question 16

State the colour of thymolphthalein in CH₃COOH(aq).

Answer 16

Colourless

Question 17

Identify the substance with the highest concentration of H⁺(aq) ions and explain your answer.

Answer 17

HNO₃; it has the lowest pH (pH1), indicating the highest [H⁺].

Question 18

Name an indicator that can be used to identify the substance with the highest concentration of H⁺(aq) ions.

Answer 18

Methyl orange

Question 19

Write the dissociation equation for ethanoic acid: CH₃COOH(aq) →

Answer 19

H⁺(aq) + CH₃COO⁻(aq)

Question 20

Write the ionic equation for a neutralisation reaction between any acid and any alkali.

Answer 20

H⁺(aq) + OH⁻(aq) → H₂O(l)

Question 21

Calculate the number of moles of Ca(OH)₂ used: 20.0 cm³ of 0.0150 mol/dm³.

Answer 21

0.000300 mol

Question 22

Determine the number of moles of HNO₃ which react with the Ca(OH)₂.

Answer 22

0.000600 mol

Question 23

Calculate the concentration of HNO₃ in mol/dm³.

Answer 23

0.0240 mol/dm³

Question 24

Calculate the concentration of HNO₃ in g/dm³.

Answer 24

1.512 g/dm³

Question 25

Name the type of bonding in lithium, sodium and potassium.

Answer 25

Metallic bonding

Question 26

State the test for hydrogen gas and the positive result.

Answer 26

Pop test; a squeaky pop is heard.

Question 27

Suggest the pH of a solution of a strong alkali.

Answer 27

Approximately 14

Question 28

Name a substance that can be used to confirm the pH of a solution of a strong alkali.

Answer 28

Phenolphthalein

Question 29

Write the symbol equation for the reaction between sodium and cold water.

Answer 29

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

Question 30

Which equation letter A–J represents a neutralisation reaction?

Answer 30

B

Question 31

Which gas from the list forms an alkaline solution when dissolved in water?

Answer 31

Ammonia

Question 32

State what is meant by the term acid.

Answer 32

A proton donor.

Question 33

State the meaning of 'weak' in the term weak acid.

Answer 33

Partially dissociates in solution.

Question 34

Determine the oxidation number of phosphorus in the PO₄³⁻ ion.

Answer 34

5