Extracting metals from their ores

Why should metals be recycled?

1. It saves energy e.g. less energy is needed to melt Al than to obtain Al from its ore by electrolysis. 2. It saves natural resources as less ...(named ore) is used 3. There is less mining of ...(named ore) so there are fewer environment problems like loss of habitat 4. It reduces carbon footprint

Why do you need to maintain a high temperature in the blast furnace?

A high temperature has to be maintained in the furnace, so that the iron is produced in a molten state and can be tapped off as a liquid.

Give one physical difference between a typical metal oxide and a non metal oxide.

A metal oxide has a high melting point. A non metal oxide has a low melting point.

How do the diagrams show that titanium is an element.

All the atoms are the same.

Why is aluminium oxide not reduced to aluminium using carbon?

Aluminium is more reactive than carbon. Therefore carbon cannot reduce aluminium oxide to aluminium.

There is a greater percentage of bauxite in the Earth's crust as compared to haematite.why is aluminium more expensive than iron?

Aluminium is obtained from its ore by electrolysis. Electrolysis is an expensive process because it uses large amounts of electricity/energy Iron is obtained from its ore by reduction using carbon which is easily available.

Give one reaction for an acid-base reaction that takes place in the blast furnace

CaO + SiO² --> CaSiO³

Why does the oxide of calcium reactor with oxide of silicon?

Calcium oxide/ CaO is basic. Silicon (IV) oxide/ SiO² is acidic. Therefore they react to form a salt, calcium silicate.

Why does carbon reduce zinc oxide to zinc.

Carbon is more reactive than zinc. It therefore removes oxygen from zinc oxide and reduces zinc oxide to zinc. 2ZnO + C --> 2Cu + CO²

Give one equation for a redox reaction that takes place in the blast furnace.

Fe²O³ + 3CO --> 2Fe + 3CO²

Why is carbon not needed to extract gold from the Earth's rocks?

Gold is found as an element

Gold occurs native in the Earth's crust. Explain.

Gold is found as an element in the Earth's crust because it is an unreactive metal.

Zinc is made by reducing zinc oxide. Suggest a way of changing calamine into zinc oxide.

Heat the zinc carbonate strongly. ZnCO³ --> ZnO + CO²

Explain how oxygen can be removed from zinc oxide to make zinc. Use the Reactivity Series to help you.

Heat the zinc oxide with carbon. As carbon is more reactive than zinc it removes oxygen from zinc oxide and reduces it to zinc. As carbon is more reactive than zinc it removes oxygen from zinc oxide and reduces it to zinc. 2ZnO + C --> 2Zn + CO²

About 5000 years passed between the first extraction of iron and that of aluminium. Explain.

Iron is extracted from its oxide by reduction using carbon. Aluminium is extracted from its oxide by electrolysis. Electrolysis was not discovered until recently.

Give some ways in which the extraction of metals can affect the environment.

It destroys the habitats of animals and birds. It destroys the landscape. Increased traffic causes air pollution and noise pollution. It leads to the depletion of natural resources.

Why are different methods of extraction used for iron and aluminium?

It is more difficult to extract aluminium from its oxide because Al is more reactive than iron. Aluminium cannot be extracted from its oxide by reduction with carbon because aluminium is more reactive than carbon.

Give the environmental benefits of recycling a higher percentage of used steel cans.

It saves natural resources as less iron ore is used. There is less mining of the ore/ It reduces the use of landfill sties. Less fuel is used.

Why is limestone added to the furnace?

Limestone removes acidic impurities like silica/silicon (IV) oxide/ SiO² SiO² is neutralised by CaO.

Give one chemical difference between a typical metal oxide and a non metal oxide.

Metal oxide are basic. Non metal oxide a are acidic.

Why is aluminium more expensive than iron?

More energy is needed to extract aluminium from its ore. Aluminium cannot be extracted from its oxide by reduction with carbon.

Titanium is extracted from its ore rutile by electrolysis. Rutile contains titanium dioxide. Give reasons why titanium is much more expensive than iron.

More energy is needed to extract titanium from it's ore. Titanium cannot be extracted by reduction using carbon.

Chemical equations are always balanced. Explain why.

No atoms are lost or made during a chemical reaction.

Zinc is extracted by removing oxygen from zinc oxide. What name is given to a reaction in which oxygen is removed from. A substance?

Reduction

Reasons for recycling aluminium

Saves energy Saves natural resources There is less mining of the ore.

Suggest why the reactor contains argon and not air.

Sodium does not react with argon because argon is unreactive. If air was present in the reactor then sodium would react with oxygen in the air producing sodium oxide.

Suggest what the reactor contains argon and not air.

Sodium does not react with argon because argon is unreactive. If air was present in the reactor then sodium would react with oxygen in the air producing sodium oxide.

What does the reaction above tell you about the reactivity of sodium compared with titanium?

Sodium is more reactive than titanium.

Zinc oxide is used to make aqueous zinc chloride. This can be used to preserve wood. Describe how this solution could be made.

Take 25cm³ of dilute hydrochloric acid in a beaker and warm the acid. Add excess zinc oxide to the acid. Filter the mixture to remove the excess zinc oxide. The filtrate is a solution of zinc chloride.

List some factors that contribute to the price of a metal.

The abundance of the ore in the Earth's crust. The mining costs. The energy costs in the process of extracting the metal from its ore. The demand for the metal.

In this electrolysis, aluminium and oxygen gas are produced from the aluminium oxide. Suggest why most of the waste gas is carbon dioxide and not oxygen.

The anodes are made of carbon. Oxygen formed at the positive electrode reacts with carbon due to the high temperature in the cell producing carbon dioxide

Suggest why the anodes disappear and have to be replaced frequently

The anodes are made of carbon. Oxygen formed at the positive electrode reacts with carbon due to the high temperature in the cell producing carbon dioxide which escapes as a gas.

Suggest an explanation why high carbon steel is less malleable and harder than mild steel.

The carbon atoms in the structure are of a different size to the metal ions, so reduces movement and prevents the layers sliding.

What would you observe in the diagram below after two weeks? [Diagram includes damp iron wool, air and water]

The iron wool will rust. The water rises up the test tube because the iron reacts with the oxygen in the air.

Both iron and steel have typical metallic structures. Explain why, when a force is applied to a piece of steel, it does not break but just changes its shape.

The layers of ions slide over each other.

Suggest why the aluminium is produced in the electrolysis cell as a liquid.

The melting point of aluminium is lower than 950°C (given in Q/diagram)

Give one use for the waste gases.

The waste gases are used to heat the incoming air.

Give 2 uses for cast iron.

To make drain covers and gates.

Give the functions of coke

To provide heat energy. To produce the reducing g agent, carbon monoxide, CO.

Why is hot air blown into the furnace?

To provide oxygen for the coke to burn in. To maintain a high temperature in the blast furnace.

How do the diagrams show that sodium chloride is a compound.

Two different elements are chemically bonded together.

Describe how zinc is extracted from zinc blende.

Zinc sulphide is heated in air. Zinc oxide and sulphur dioxide are formed. 2ZnS + 3O² --> 2ZnO + 2SO² Zinc oxide is.mized with coke and heated very strongly. Coke reduces zinc oxide to zinc. 2Zn + C --> 2Zn + CO²