Making soluble salts

Zinc reacts with iodine to produce the salt zinc iodide.

The reaction is done in a solution using ethanol as the solvent.

Ethanol is a flammable liquid with a boiling point of 78 °C.

Table 5 shows the solubility of zinc, iodine and zinc iodide in ethanol.

Plan a method to obtain crystals of zinc iodide from zinc and iodine.

A student used 6.35 g of iodine in the reaction.

6.29 g of zinc iodide was produced.

The equation for the reaction is:

Calculate the percentage yield of zinc iodide.

Give your answer to 3 significant figures.

Relative formula masses (M_r): I₂ = 254 ZnI₂ = 319

A student produced a salt by reacting copper carbonate with sulfuric acid.

This is the method used.

1. Measure 50 cm³ of sulfuric acid into a beaker.

2. Add copper carbonate powder.

3. Stir the mixture.

4. Repeat steps 2 and 3 until copper carbonate is in excess.

5. Filter the mixture.

6. Warm the filtrate gently until crystals start to appear.

7. Leave the solution to cool and crystallise.

Complete the word equation for the reaction.

copper + sulfuric → + + carbon

Give one observation the student could make during Step 4 which shows that the copper carbonate is in excess.

Give one reason for filtering the mixture in Step 5.

Name the equipment that can be used to warm the filtrate gently in Step 6.

The maximum theoretical mass of the salt that could be produced using 50 cm³ of the sulfuric acid is 12.5 g.

The percentage yield of the salt is 92.8%.

Calculate the mass of salt actually produced.

Use the equation:

Some salts can be produced by reacting sulfuric acid with a metal.

Neither copper nor sodium is used to produce a salt with sulfuric acid.

Give one reason why each metal is not used.

A student produced a salt by reacting copper carbonate with sulfuric acid.

This is the method used.

1. Measure 50 cm³ of sulfuric acid into a beaker.

2. Add copper carbonate powder.

3. Stir the mixture.

4. Repeat steps 2 and 3 until copper carbonate is in excess.

5. Filter the mixture.

6. Warm the filtrate gently until crystals start to appear.

7. Leave the solution to cool and crystallise.

Complete the word equation for the reaction.

copper + sulfuric → + + carbon

Give one observation the student could make during Step 4 which shows that the copper carbonate is in excess.

Give one reason for filtering the mixture in Step 5.

Name the equipment that can be used to warm the filtrate gently in Step 6.

The maximum theoretical mass of the salt that could be produced using 50 cm³ of the sulfuric acid is 12.5 g.

The percentage yield of the salt is 92.8%.

Calculate the mass of salt actually produced.

Use the equation:

Some salts can be produced by reacting sulfuric acid with a metal.

Neither copper nor sodium is used to produce a salt with sulfuric acid.

Give one reason why each metal is not used.

This question is about making a soluble salt.

Plan a method to make pure, dry crystals of zinc chloride from zinc carbonate and a dilute acid.

Name two other substances that can each be reacted with a dilute acid to make zinc chloride. Do not refer to zinc carbonate in your answer.

This question is about making a soluble salt.

Plan a method to make pure, dry crystals of zinc chloride from zinc carbonate and a dilute acid.

Name two other substances that can each be reacted with a dilute acid to make zinc chloride. Do not refer to zinc carbonate in your answer.

This question is about zinc and compounds of zinc. A student produces pure crystals of zinc chloride by reacting zinc oxide with hydrochloric acid. The equation for the reaction is:

The student adds zinc oxide to hydrochloric acid until the zinc oxide is in excess. Give one observation that the student could make to show that the zinc oxide is in excess.

Why is excess zinc oxide used rather than excess hydrochloric acid?

Name one other compound that the student could add to hydrochloric acid to produce zinc chloride.

Describe how the student should obtain crystals of zinc chloride from a solution of zinc chloride.

Zinc chloride is also produced in a displacement reaction between zinc and copper chloride solution. The equation for the reaction is:

Complete the ionic equation for this reaction.

Why is zinc described as being oxidised in this reaction?

Zinc and copper can be used with another substance to produce electricity. Complete Figure 7 to show how zinc, copper and another substance can be used to light a lamp. Label:

• zinc

• copper

• the other substance used.

The symbol represents the lamp.

This question is about metal carbonates.

A student investigated the reaction of copper carbonate with an acid.

Figure 8 shows the apparatus.

This is the method used.

1. Pour 25 cm³ of the acid into a conical flask.

2. Weigh 0.10 g of copper carbonate.

3. Remove the stopper and add the copper carbonate to the flask.

4. Quickly replace the stopper.

5. Record the maximum volume of gas collected in the gas syringe.

6. Repeat steps 1 to 5 with different masses of copper carbonate.

Figure 9 shows the gas syringe during the experiment.

What is the reading on the gas syringe?

The student plotted the results on a graph.

Figure 10 shows the student’s graph.

Determine the gradient of the line of best fit.

You should:

• calculate the values of the change in y and the change in x

• calculate the gradient of the line of best fit.

Copper chloride was produced in the reaction.

Which acid reacts with copper carbonate to produce copper chloride?

Tick (✓) one box.

The reaction between copper carbonate and the acid produced a gas.

What was the gas?

Tick (✓) one box.

A different student produced a pure, dry sample of copper chloride using the same reaction.

This is the method used.

1. Add excess copper carbonate to the acid.

2. Filter the mixture.

3. Heat the solution gently until crystals start to form.

4. Leave for 24 hours.

5. Remove the crystals.

6. Rinse with water and dry the crystals.

Why was the solution heated gently in step 3 ?

Tick (✓) one box.

How should the solution be heated gently in step 3 ?

This question is about salts.

Name the salt produced by the neutralisation of hydrochloric acid with potassium hydroxide.

Write an ionic equation for the neutralisation of hydrochloric acid with potassium hydroxide.

Soluble salts can be produced by reacting dilute hydrochloric acid with an insoluble solid. Copper, copper carbonate and copper oxide are insoluble solids. Which of these insoluble solids can be used to make a copper salt by reacting the solid with dilute hydrochloric acid? Tick (✓) one box.

A student makes crystals of magnesium sulfate. This is the method used.

1. Add sulfuric acid to a beaker.

2. Warm the sulfuric acid.

3. Add a spatula of magnesium oxide to the beaker.

4. Stir the mixture.

5. Repeat steps 3 and 4 until there is magnesium oxide remaining in the beaker.

6. Filter the mixture.

7. Evaporate the filtrate gently until crystals start to form.

8. Leave the solution to finish crystallising.

Give one reason for:

• step 2

• step 5

• step 6.

How should the filtrate be evaporated gently in step 7 ?

Iron chloride is produced by heating iron in chlorine gas. The equation for the reaction is:

Calculate the volume of chlorine needed to react with 14 g of iron. You should calculate:

• the number of moles of iron used

• the number of moles of chlorine that react with 14 g of iron

• the volume of chlorine needed.

Relative atomic mass (A_r): Fe = 56 The volume of 1 mole of gas = 24 dm³

Soluble salts are formed by reacting metal oxides with acids.

Give one other type of substance that can react with an acid to form a soluble salt.

Calcium nitrate contains the ions Ca²⁺ and NO₃^–

Give the formula of calcium nitrate.

Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and a dilute acid.

Soluble salts are formed by reacting metal oxides with acids.

Give one other type of substance that can react with an acid to form a soluble salt.

Calcium nitrate contains the ions Ca²⁺ and NO₃^– Give the formula of calcium nitrate.

Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and a dilute acid.