Obtaining & Using Metals (Edexcel GCSE Chemistry)

A student carried out an experiment to see how reactive different metals are when they are placed in dilute hydrochloric acid. A sample of each metal was placed in a separate test tube of acid.

When zinc reacts with dilute hydrochloric acid, a gas is given off and zinc chloride is formed.

i) Which gas is given off?

(1)

ii) What is the formula of zinc chloride?

(1)

In the experiment, the student used the same amount of each metal in a finely powdered form.

State two factors, concerning the hydrochloric acid, which should also be controlled to produce valid results.

Part of the reactivity series is shown in Figure 8.

Figure 8

Iron is extracted from its ore by heating with carbon. Aluminium is extracted from its ore using a different method.

i) Give the name of the method used to extract aluminium.

(1)

ii) Explain why aluminium is extracted by a different method rather than heating the ore with carbon.

(2)

The extraction of iron involves the reduction of iron oxide, Fe₂O₃, by carbon monoxide, CO. During this reaction, the iron oxide is reduced to iron, Fe, and the carbon monoxide is oxidised to carbon dioxide.

Write the balanced equation for the reaction.

Some metals, such as aluminium, are extracted from their ores using electrolysis. 

Why are some metals extracted using electrolysis? 

Most metals are extracted from ores found in the Earth’s crust.

The method used to extract a metal from its ore is linked to the reactivity of the metal.

Part of the reactivity series is shown in Figure 14.

Figure 14

Iron ore contains iron oxide.

Iron is extracted from iron oxide by heating the oxide with carbon.

iron oxide + carbon → iron + carbon dioxide

i) In this reaction

(1)

ii) The formula of the iron oxide is Fe₂O₃. Calculate the maximum mass of iron that can be obtained from 240 tonnes of iron oxide, Fe₂O₃. (relative atomic masses: O = 16, Fe = 56) (3)

Aluminium cannot be extracted by heating its oxide with carbon.

Aluminium has to be extracted from its oxide by electrolysis.

Explain why.

Predict the method that will have to be used to extract calcium from its ore.

Aluminium is extracted from its ore by electrolysis.

Iron is extracted from its ore by heating with carbon.

Both metals can also be obtained by recycling.

Explain the advantages of recycling aluminium and iron rather than extracting them from their ores.

Higher Only

In recent years, researchers have been investigating alternative methods of extracting metals from soils.

Researchers have found that growing certain plants in appropriate areas can result in the phytoextraction of copper.

Describe how growing plants can result in the phytoextraction of copper.

Which of the following metals can not be extracted from its ore by reduction?

Metals are extracted from substances naturally occurring in the Earth’s crust.

Which of these metals is usually found uncombined in the Earth's crust? 

Zinc can be extracted by heating zinc oxide with carbon.

The products are zinc and carbon dioxide.

 i) Write the word equation for this reaction. 

(2)

ii) In this reaction zinc oxide loses oxygen.

State the type of reaction taking place when an oxide loses oxygen. 

(1)

Aluminium is extracted from aluminium oxide by electrolysis.

Aluminium oxide is made up of ions.

i) The formula of aluminium oxide is Al₂O₃.

Give the number of ions in the formula Al₂O₃.  

(1)

ii) Complete the balanced equation for the overall reaction by putting numbers in the spaces.  

(2)

2Al₂O₃ → ..........Al + ..........O₂

i) The environmental impact of a product is assessed in a life-cycle assessment.

The stages in this assessment are given below. They are not in the correct order.

List the stages of the life-cycle assessment, using letters A, B, C, D, in the correct order from start to finish. 

(2)

ii) Aluminium can be obtained by recycling aluminium waste.

Give two advantages of obtaining aluminium by recycling aluminium waste rather than mining the raw material and extracting aluminium from that raw material.  

(2)

A student was investigating the reactivity of different metals in hydrochloric acid. 

What must the student keep constant in this investigation to make it a fair experiment?

(1)

Higher Only

One way to extract metals from land contaminated with metal compounds is phytoextraction.

When plants grow they absorb metal ions through their roots.

The plants are harvested, dried and burned forming an ash.

The ash contains metal compounds.

Plants were grown in a piece of ground contaminated with nickel compounds.

i) 1 kg of the ash from these plants contained 142.0 g of nickel compounds. Calculate the percentage by mass of nickel compounds in the ash.

(3) 

percentage by mass = ...............................  

ii) Nickel is extracted from nickel compounds.

 State an advantage of extracting nickel by phytoextraction rather than from its ore. 

(1)

Some nickel ores contain nickel sulfide.

i) In the first stage of extracting nickel from nickel sulfide, the nickel sulfide, NiS, is heated in air to form nickel oxide, NiO, and sulfur dioxide. Write the balanced equation for this reaction.

(2)

ii) In the final stage of the extraction process, a nickel compound is electrolysed to produce pure nickel.

An advantage of producing a metal by electrolysis is that:

(1)

In a different method of obtaining nickel, the process produces a mixture of the liquids nickel tetracarbonyl and iron pentacarbonyl.

The boiling point of nickel tetracarbonyl is 43 °C. The boiling point of iron pentacarbonyl is 103 °C. These two liquids mix together completely. 

Describe the process used to separate these two liquids.

Some metals are unreactive and exist on their own in the earth. 

What are these metals known as?

Pieces of zinc react with copper sulfate solution. Zinc sulfate solution is colourless.

Zn (s) + CuSO₄ (aq) → Cu (s) + ZnSO₄ (aq)

Describe what you would see when an excess of zinc is added to copper sulfate solution and the mixture left until the reaction is complete.

Higher Only

This reaction is described as a redox reaction.

Explain, in terms of electrons, which particles have been oxidised and which particles have been reduced in this reaction.

Higher Only

The copper sulfate solution used has a concentration of 15.95 g dm⁻³.

Calculate the number of moles of copper sulfate, CuSO₄, in 50.00 cm³ of this solution.

(relative atomic masses: O = 16, S = 32, Cu = 63.5)

 number of moles of copper sulfate = ............................... mol

In another experiment, 0.043 mol of copper sulfate, CuSO₄, is used. 

Calculate, to one decimal place, the minimum mass of zinc that must be added to react with all the copper sulfate.

(relative atomic mass: Zn = 65)

mass = ............................... g

Zinc is extracted from zinc oxide by reduction.

Which element is oxidised during this process?

Some metals are found in the Earth’s crust as uncombined elements. Reactive metals are found in ores. In ores, metals are combined with other elements.

Which of these metals is found as the uncombined element in the Earth’s crust?

Give two advantages of recycling metals rather than extracting metals from their ores.

An ore of iron is mostly iron oxide, Fe₂O₃. Iron can be extracted from this iron oxide by heating it with carbon.

Balance this equation for the reaction that takes place.

2Fe₂O₃ + ................C → ................Fe + ................CO₂

Most copper ores are described as low grade. This means that the percentage of copper in the ore is very small.

5000 kg of one copper ore was found to contain 42.5 kg of copper.

Calculate the percentage of copper in this ore.

percentage of copper in ore = ...........................................

In one stage of the extraction of lead from its ore, lead oxide is heated strongly with carbon.

The equation for the reaction is 

2PbO + C → 2Pb + CO₂ 

Explain, using this equation, which substance has been oxidised in this reaction.

A titanium ore was analysed and found to contain 12 g of titanium atoms combined with 8.0 g of oxygen atoms.

Calculate the empirical formula of this titanium compound. (relative atomic masses: Ti = 48, O = 16)

You must show your working.

empirical formula = ............................................

Coffee cups are usually made from ceramic, glass, paper, plastic or metal.

Some of these materials are recyclable. In a Life Cycle Assessment (LCA) where would this information be given?

When chromium reacts with oxygen, chromium oxide is formed.

i) Write the word equation for this reaction.

(1)

............... + ................ → ..............

ii) What type of reaction occurs when chromium reacts with oxygen?

(1)

iii) Calculate the relative formula mass of chromium oxide, Cr₂O₃.

(relative atomic masses: O = 16, Cr = 52)

(2)

relative formula mass = .............................................................

Three different metals are added to separate test tubes of acid.

The observations are shown in Figure 4.

Figure 4

i) Place the metals in order of reactivity from most to least reactive.

(1)

most reactive .............................................................
least reactive .............................................................

ii) Hydrogen is given off when magnesium reacts with acid.

The hydrogen is tested by collecting the gas in a test tube and igniting it.

What is the safest way to ignite the gas?

(1)

iii) State the observation made in this test that shows that the gas is hydrogen.

(1)

Iron is extracted by heating iron oxide with carbon.

Electrolysis of molten iron oxide is not used to extract iron.

i) State why iron can be extracted by heating iron oxide with carbon.

(1)

ii) State why electrolysis is not used to extract iron.

(1)

Higher Only 

Copper can be extracted from low grade ores using bioleaching. 

A leachate solution is produced.

Which process is used to extract the copper from the leachate solution?

A reaction took place between iron sulfate and magnesium. 

iron(II) sulfate + magnesium  →    magnesium sulfate + iron 

Which species has been oxidised?

The order of reactivity of copper, magnesium and zinc can be determined by the displacement reactions between these metals and solutions of their salts.

You are provided with

• samples of the three metals

• solutions of copper sulfate, magnesium sulfate and zinc sulfate.

Describe the experiments that can be done to determine the order of reactivity of these metals by displacement reactions.

Metals can be extracted from ores found in the Earth’s crust.

Explain why aluminium cannot be extracted from its ore by heating with carbon but can be extracted by electrolysis.

Titanium is extracted from its ore in several stages.

In the first stage, titanium chloride is formed as a gas.

The gas is cooled to form liquid titanium chloride containing dissolved impurities.

Suggest how pure titanium chloride could be separated from the impurities.

Higher Only

In another stage, the pure titanium chloride, TiCl₄ , is reacted with 500 moles of magnesium, an excess.

TiCl₄ + 2Mg → Ti + 2MgCl₂

i) Calculate the number of moles in 45 000 grams of titanium chloride. (relative atomic masses: Cl = 35.5, Ti = 48.0)

(2)

number of moles titanium chloride = ...............................................................

ii) Show that the 500 moles of magnesium added is an excess.

(1)

After this reaction, there is a mixture of the solids magnesium, titanium and magnesium chloride.

Titanium does not react with dilute hydrochloric acid.

Suggest a simple method to separate titanium from the mixture.

Phytomining can be used to extract copper compounds from the soil.

Plants are grown on the soil and they absorb the copper compounds through their roots. The plants are then harvested, dried and burnt to form an ash.
The ash contains the copper compounds.

One example of a copper compound extracted this way is copper oxide.
The copper oxide is added to acid where it reacts to form copper sulfate solution.
Give the formula of the acid used in this reaction.

Higher Only

Copper is extracted from copper sulfate solution using scrap iron.

Explain why it is economical to use scrap iron for this function.

Explain why scrap iron can be used to extract copper from copper sulfate.

Higher Only

Describe one advantage of extracting copper by phytoextraction rather than from its ore.

Lead is found in the Earth’s crust in ores. In ores, the lead is combined with other elements.

5000 kg of lead ore was found to contain 48 200 g of lead.

Calculate the percentage of lead in the ore. Give your answer to 2 significant figures.

The lead ore contains lead oxide (PbO).
To extract lead from lead oxide it is heated strongly with carbon.

Write the balanced symbol equation for this reaction.

Explain which substance is oxidised, and which is reduced.

Figure 1 shows the reactivity series of metals.

A non-metal - carbon - has also been included.

Figure 1

Use Figure 1 to explain why:

i) Lead can be extracted from its ores by heating with carbon.

[1]

ii) Aluminium can only be extracted from its ores using electrolysis.

[1]

Calcium is added to a beaker of silver nitrate solution.

A reaction takes place.

The symbol equation for the reaction is:

Ca(s) + 2AgNO₃(aq) → Ca(NO₃)₂ (aq) + 2Ag(s)

Explain why this reaction happens in terms of reactivity.

Higher Only

Write the ionic equation for this reaction.

Higher Only

Explain why this reaction is an example of a redox reaction.

Potassium is more reactive than calcium.

Use the electronic structure of these elements to suggest why.

Figure 1 shows how five different metals - A, B, C and D react when heated in oxygen.

The same size and shape piece of metal was used for each.

Figure 1

Most of the metals undergo a chemical reaction.

i) Give one sign from Figure 2 that is evidence that a chemical reaction has happened.

[1]

ii) Name this reaction.

[1]

Order the metals in terms of reactivity, starting with the least reactive.

The same metals are added to dilute hydrochloric acid.

Write the balanced symbol equation when magnesium reacts with hydrochloric acid.

Predict what would be observed when:

i) Metal C is added to the acid.

[1]

ii) Metal B is added to the acid.

[1]