All Saints Secondary Standard Grade Chemistry

Topic 9 Homework – Reactions of Acids

(Credit Level)

1. Many pairs of chemicals react together.

A / B / C
ammonium chloride
+
sodium hydroxide solution / silver
+
dilute hydrochloric acid / copper oxide
+
dilute sulphuric acid
D / E / F
sodium hydroxide solution
+
dilute nitric acid / sodium
+
water / zinc
+
copper sulphate solution

(a)Identify the pair(s) of chemicals which react to produce a gas.

1 mark (KU)

(b)Identify the pair of chemicals which will not react.

1 mark (KU)

2. The grid shows the names of some soluble compounds.

A / B / C
magnesium bromide / sodium bromide / lithium hydroxide
D / E / F
sodium iodide / potassium sulphate / lithium chloride

(a) Identify the base.

1 mark (PS)

(b) Identify the two compounds whose solutions would form a precipitate when mixed.

You may wish to use the data booklet to help you.

1 mark (PS)

(c) Identify the compound with a formula of the type XY2, where X is a metal.

1 mark (PS)

3. The grid below shows pairs of chemicals.

A / B
Mg(s) + HCl(aq) / NaOH(aq) + H2SO4(aq)
C / D
Cu(s) + H2SO4(aq) / Zn(s) + AgNO3(aq)
E / F
CuSO4(aq) + Na2CO3(aq) / CaCO3(s) + HCl(aq)

(a)Identity the pair(s) which would react to produce water.

1 mark (KU)

(b)Identify the pair which would not react

1 mark (KU)

4. The grid shows some statements which could be applied to a solution.

A / It / does not / react with magnesium.
B / It / has a pH / less than 7.
C / It / does not / conduct electricity.
D / It / produces chlorine gas when electrolysed.
E / It / contains / more H+ ions than pure water.

Identify the two statements which are true for both dilute hydrochloric acid and dilute sulphuric acid.

2 marks (KU)

5. Clare carried out an experiment to make copper chloride crystals.

Instructions for preparation of copper chloride crystals Step 1Add 25 cm3 of dilute hydrochloric acid to a beaker.

Step 2Add a spatulaful of copper carbonate powder to the acid and stir.

Step 3Continue adding copper carbonate until some of the solid remains.

Step 4 Step 5

(a)Why did Clare continue to add copper carbonate until some solid remained?

1 mark (PS)

(b)Name the two techniques which Clare would have carried out in steps 4 and 5 to prepare a sample of copper chloride crystals.

2 marks (PS)

6. Stuart wanted to prepare ammonium sulphate.

He carried out a titration using 0-3 mol/1 sulphuric acid and 0.5 mol/1 ammonia solution.

The equation for the reaction is

2NH3(aq) + H2SO4(aq) (NH4)2SO4(aq)

(a)Calculate the volume of sulphuric acid Stuart used to neutralise the ammonia solution.

2 marks (KU)

(b)The indicator was removed from the ammonium sulphate solution by filtering the solution through charcoal.

How would Stuart then obtain a sample of solid ammonium sulphate from the solution?

1 mark (PS)

7. Common salt is extracted from salt mines by pumping in water to dissolve it.

The salt solution which is obtained contains magnesium sulphate as an impurity.

The magnesium ions are removed by adding sodium hydroxide solution.

Mg2+(aq) + SO42-aq) + 2Na+(aq) + 2OH-(aq) Mg2+(OH-)2(s) + 2Na+(aq) + SO42- (aq)

(a)(i) Name the type of reaction taking place between the magnesium sulphate solution and the sodium hydroxide solution.

1 mark (KU)

(ii) Name the spectator ions in the reaction.

1 mark (KU)

(b)The products of the reaction can be separated by filtration.

Draw and label the apparatus you would use in the laboratory to carry out this process.

Indicate on the diagram where each product is collected.

2 marks (PS)

8. Vinegar is a dilute solution of ethanoic acid in water.

Rough / 1st / 2nd
titre / titre / titre
Initial burette reading/cm3 / 1.0 / 21.7 / 11.7
Final burette reading/cm3 / 21.7 / 41.7 / 31.9
Volume used/cm3 / 20.7 / 20.0 / 20.2


Karen carried out a titration to find out the concentration of ethanoic acid in some vinegar.

(a) Karen used data from the table to calculate an average volume of sodium

hydroxide solution. She used this average volume to calculate the number of moles of sodium hydroxide needed to neutralise the acid in 25 cm3 of the vinegar.

(i)What average volume of sodium hydroxide should she have used?

1 mark (PS)

(ii)Calculate the number of moles of sodium hydroxide in this average volume.

Show your working clearly.

1 mark (KU)

(b) 1 mole of ethanoic acid reacts with 1 mole of sodium hydroxide. Calculate the concentration, in mol/l, of ethanoic acid in the vinegar.

Show your working clearly.

1 mark (KU)


9. Silver nitrate solution can be used to determine the mass of chloride ions in 1 litre of sea water.

Volume of silver nitrate solution used to reach the end-point = 10.8 cm3.

(a)(i) How many moles of silver nitrate does 10.8 cm3 of 0.05 mol/l silver nitrate solution contain?

Show your working clearly.

1 mark (KU)

(ii) One mole of silver nitrate solution reacts with one mole of chloride ions.

How many moles of chloride ions are there in 1 litre of the sea water?

Show your working clearly.

1 mark (KU)

(iii) Calculate the mass of chloride ions in 1 litre of the sea water.

Show your working clearly.

1 mark (KU)

(b) The end point of the titration is indicated by the formation of red silver(I)

chromate.

Write the formula for silver(I) chromate.

1 mark (KU)


10. Sodium carbonate reacts with hydrochloric acid to form carbon dioxide. Brian measured the volume of carbon dioxide given off over a period of time and recorded his results.

(a)Complete and label the diagram to show how Brian measured the volume of carbon dioxide.

2 mark (PS)

(b) Brian's results are shown below.

Time/s / 0 / 10 / 30 / 40 / 50 / 60 / 70
Volume of carbon
dioxide/cm3 / 0 / 12 / 29 / 34 / 36 / 37 / 37

Draw a line graph of the results.

Use appropriate scales to fill most of the graph paper.

2 marks (PS)

Suggest a value for the volume of carbon dioxide collected during the first 20 seconds.

1 mark (PS)

(c) Write the ionic formula for sodium carbonate.

1 mark (KU)

11. Gillian investigated the ability of different substances to conduct electricity

when dissolved in water.

Here are her results.

Substance / Concentration of solution / Current
(mol/1) / (mA)
sodium chloride / 0.005 / 21
sodium chloride / 0.002 / 11
sodium chloride / 0.001 / 7
hydrochloric acid / 0.005 / 62
hydrochloric acid / 0.002 / 27
hydrochloric acid / 0.001 / 20
sodium hydroxide / 0.005 / 32
sodium hydroxide / 0.002 / 15
sodium hydroxide / 0.001 / 11

(a)What name is used to describe a solution which conducts electricity?

1 mark (KU)

(b)Identify two variables which she would have kept constant to make sure that her results were fair.

1 mark (PS)

(c)From the results, state the effect of changing concentration on the ability of a substance to conduct electricity when dissolved in water.

1 mark (PS)

(d)Arrange the three substances in order of their ability to conduct electricity when dissolved in water.

(Put the best conductor first.)

1 mark (PS)


12.A pupil carried out a titration using the chemicals and apparats shown below.

Rough / 1st / 2nd
titre / titre / titre
Initial burette reading/cm3 / 0.5 / 21.7 / 0.3
Final burette reading/cm3 / 21.7 / 42.4 / 20.8
Volume used/cm3 / 21.2 / 20.7 / 20.5

(a)How would the pupil know when to stop adding acid from the burette?

1 mark (PS)

(b)(i) What average volume should be used to calculate the number of moles of sulphuric acid needed to neutralise the potassium hydroxide solution?

1 mark (PS)

(ii) Calculate the number of moles of sulphuric acid in this average volume.

Show your working clearly.

1 mark (KU)

(iii) The equation for the titration reaction is

H2S04 + 2KOHK2S04 + 2H20

Calculate the number of moles of potassium hydroxide in 20 cm' of the potassium hydroxide solution.

Show your working clearly.

1 mark (KU)

Topic 9 Homework – Credit Level