Relative formula mass

This question is about energy changes of reactions.

Zinc reacts with copper sulfate solution.

The word equation for the reaction is:

zinc + copper sulfate → zinc sulfate + copper

What type of reaction is the reaction between zinc and copper sulfate solution?

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Calculate the percentage (%) by mass of copper in copper sulfate (CuSO₄).

Give your answer to 3 significant figures.

Relative atomic mass (A_r): Cu = 63.5

Relative formula mass (M_r): CuSO₄ = 159.5

A student investigated the energy change in the reaction between zinc and copper sulfate solution.

This is the method used.

1. Measure 25 cm³ of copper sulfate solution into a polystyrene cup.

2. Weigh 0.20 g of zinc powder.

3. Add the zinc powder to the copper sulfate solution.

4. Measure the highest temperature reached by the mixture.

5. Repeat steps 1 to 4 using different masses of zinc powder.

Control variables are used to make an investigation a fair test.

Which is a control variable in the investigation?

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Figure 6 shows the results.

What is the minimum mass of zinc powder needed to react with all the copper sulfate solution?

Use Figure 6.

What is the maximum temperature change in the reaction between zinc powder and 25 cm³ of copper sulfate solution?

Use Figure 6.

25 cm³ of copper sulfate solution contained 6.75 g of copper sulfate.

Calculate the concentration of the solution in g/dm³.

You should:

calculate the volume of the solution in dm³ (1000 cm³ = 1 dm³)

use the equation:

Another student investigated the energy change of the reaction between sodium hydrogencarbonate and hydrochloric acid.

This is the method used.

1. Measure 25 cm³ of hydrochloric acid.

2. Weigh 1.0 g of sodium hydrogencarbonate.

3. Add the sample of sodium hydrogencarbonate to the hydrochloric acid.

4. Measure the lowest temperature reached by the mixture.

5. Repeat steps 1 to 4 using different masses of sodium hydrogencarbonate.

Figure 7 shows the results.

Draw two straight lines of best fit on Figure 7.

The lines should cross.

Which statement describes the energy change in the reaction shown in Figure 7 ?

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This question is about electrolysis and the extraction of metals.

Why can some molten substances be electrolysed?

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Table 3 shows the products of the electrolysis of some molten compounds.

Complete Table 3.

Aluminium is extracted by electrolysing molten aluminium oxide.

Balance the equation for the reaction.

Choose numbers from the box.

Calculate the relative formula mass (M_r) of aluminium oxide (Al₂O₃).

Relative atomic masses (A_r): O = 16 Al = 27

Figure 13 shows part of the reactivity series of metals.

The non-metal carbon has been included.

Metals can be extracted from their compounds by:

electrolysis

reduction with carbon.

Electrolysis is more expensive than reduction with carbon.

Predict one metal that would be extracted by each method.

Use Figure 13.

This question is about iron.

Iron is a metal.

Describe how iron conducts thermal energy.

Pure iron is too soft for many uses.

Explain why mixing iron with other metals makes alloys which are harder than pure iron.

When iron reacts with chlorine, 0.12 mol of iron reacts with 0.18 mol of chlorine (Cl₂).

Which is the correct equation for the reaction?

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The most common oxides of iron are Fe₂O₃ and Fe₃O₄

What is the ratio of the numbers of ions in Fe₃O₄?

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Calculate the percentage (%) by mass of iron in Fe₃O₄

Relative atomic masses (A_r): O = 16 Fe = 56

Fe₂O₃ reacts with carbon to produce carbon dioxide.

The equation for the reaction is:

Calculate the volume of carbon dioxide gas at room temperature and pressure that is produced from 40.0 kg of Fe₂O₃ using excess carbon.

Relative formula mass (M_r): Fe₂O₃ = 160

The volume of 1 mole of any gas at room temperature and pressure is 24 dm³.

This question is about displacement reactions.

Iron is extracted from iron oxide by a displacement reaction with carbon.

Balance the equation for the reaction.

Iron oxide is reduced in this reaction. How does the equation show that iron oxide is reduced?

Calculate the relative formula mass (M_r) of Fe₂O₃ Relative atomic masses (A_r): O = 16 Fe = 56

Copper oxide reacts with hydrogen to produce copper. The equation for the reaction is:

Calculate the percentage atom economy for obtaining copper from this reaction. Use the equation:

Relative atomic mass (A_r): Cu = 63.5 Relative formula masses (M_r): H₂ = 2 CuO = 79.5

A student investigated the reactivity of four different metals, A, B, C and D. The student:

• added each metal to aqueous solutions of each of the metal sulfates

• observed whether a reaction took place.

Give one observation that would show a reaction took place.

Table 4 shows the results.

shows that a displacement reaction took place. × shows that a displacement reaction did not take place. Write metals A, B, C and D in order of reactivity. Give a reason for your order of reactivity.

This question is about carbon and compounds of carbon.

Figure 9 shows diagrams that represent different structures.

Use Figure 9 to answer questions 06.1 and 06.2.

Which diagram represents graphite?

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Which diagram represents poly(ethene)?

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Figure 10 represents the structure of diamond.

How many covalent bonds does each carbon atom form in diamond?

Which is a property of diamond?

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Figure 11 shows a model of a molecule.

Complete the molecular formula of the molecule.

Molecular formula = C__ H__

Carbonic acid is a compound of carbon.

The formula of carbonic acid is H₂CO₃

Which ion is produced by carbonic acid in aqueous solution?

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Calculate the relative formula mass (M_r) of carbonic acid (H₂CO₃).

Relative atomic masses (A_r): H = 1 C = 12 O = 16

This question is about the extraction of metals.

Element R is extracted from its oxide by reduction with hydrogen.

The equation for the reaction is:

The sum of the relative formula masses (M_r) of the reactants (3 H₂ + RO₃) is 150

Calculate the relative atomic mass (A_r) of R.

Relative atomic masses (A_r): H = 1 O = 16

Identify element R.

You should use:

• your answer to question 10.1

• the periodic table.

Carbon is used to extract tin (Sn) from tin oxide (SnO₂).

The equation for the reaction is:

Calculate the percentage atom economy for extracting tin in this reaction.

Relative atomic masses (A_r): C = 12 O = 16 Sn = 119

Tungsten (W) is a metal.

Tungsten is extracted from tungsten oxide (WO₃).

All other solid products from the extraction method must be separated from the tungsten.

Table 9 shows information about three possible methods to extract tungsten from tungsten oxide.

Evaluate the three possible methods for extracting tungsten from tungsten oxide.

This question is about the extraction of metals.

Element R is extracted from its oxide by reduction with hydrogen. The equation for the reaction is:

The sum of the relative formula masses (M_r) of the reactants (3 H₂ + RO₃) is 150 Calculate the relative atomic mass (A_r) of R. Relative atomic masses (A_r): H = 1 O = 16

Identify element R. You should use:

• your answer to question 03.1

• the periodic table.

Identity of R =

Carbon is used to extract tin (Sn) from tin oxide (SnO₂). The equation for the reaction is:

Calculate the percentage atom economy for extracting tin in this reaction. Relative atomic masses (A_r): C = 12 O = 16 Sn = 119

Tungsten (W) is a metal. Tungsten is extracted from tungsten oxide (WO₃). All other solid products from the extraction method must be separated from the tungsten. Table 2 shows information about three possible methods to extract tungsten from tungsten oxide.

Evaluate the three possible methods for extracting tungsten from tungsten oxide.

This question is about the elements in Group 7 of the periodic table. Table 1 shows the melting points and boiling points of some of the elements.

What is the state of bromine at 100 °C? Use Table 1. Tick (✓) one box.

What temperature does chlorine gas condense at to form a liquid? Use Table 1.

Complete the sentences.

This is because the size of the molecules increases so the

A teacher investigated the reaction of iron with chlorine. Figure 1 shows the apparatus used.

Why did the teacher do the investigation in a fume cupboard? Tick (✓) one box.

The word equation for the reaction is: iron + chlorine → iron chloride Iron chloride is a solid. The teacher weighed the glass tube and contents:

• before the reaction

• after the reaction.

What happened to the mass of the glass tube and contents during the reaction? Give one reason for your answer.

The mass of the glass tube and contents.

The teacher repeated the investigation with bromine gas and with iodine gas. Table 2 shows the results.

Fluorine is above chlorine in Group 7. Predict what you would observe when fluorine gas reacts with iron. Use Table 2.

Balance the equation for the reaction between iron and bromine.

2 Fe + _____ Br 2 → 2 FeBr 3

Calculate the relative formula mass (M_r) of FeBr₃ Relative atomic masses (A_r): Fe = 56 Br = 80

This question is about the extraction of metals.

Tungsten is a metal. The symbol of tungsten is W Tungsten is produced from tungsten oxide by reaction with hydrogen. The equation for the reaction is:

Calculate the percentage atom economy when tungsten is produced in this reaction. Use the equation:

Relative formula masses (M_r): WO₃ = 232 H₂ = 2

Aluminium is extracted from aluminium oxide.

38% of a rock sample is aluminium oxide. Calculate the mass of aluminium oxide in 40 kg of the rock sample.

The formula of aluminium oxide is Al₂O₃ Calculate the relative formula mass (M_r) of aluminium oxide. Relative atomic masses (A_r): O = 16 Al = 27

60.0 kg of aluminium oxide produces a maximum of 31.8 kg of aluminium. In an extraction process only 28.4 kg of aluminium is produced from 60.0 kg of aluminium oxide. Calculate the percentage yield. Give your answer to 3 significant figures.

Use the equation:

Extracting metals by electrolysis is a very expensive process. Explain why aluminium is extracted using electrolysis and not by reduction with carbon.

The halogens are elements in Group 7.

Bromine is in Group 7.

Give the number of electrons in the outer shell of a bromine atom.

Bromine reacts with hydrogen. The gas hydrogen bromide is produced.

What is the structure of hydrogen bromide?

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What is the formula for fluorine gas?

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A student mixes solutions of halogens with solutions of their salts.

Table 1 shows the student’s observations.

Explain how the reactivity of the halogens changes going down Group 7.

Use the results in Table 1.

A company uses chlorine to produce titanium chloride from titanium dioxide.

What is the relative formula mass (M_r) of titanium dioxide, TiO₂ ?

Relative atomic masses (A_r): O = 16 Ti = 48

Tick one box.

The company calculates that 500 g of titanium dioxide should produce 1.2 kg of titanium chloride.

However, the company finds that 500 g of titanium dioxide only produces 900 g of titanium chloride.

Calculate the percentage yield.