Unit 10: Metals

Question 1

List the order of reactivity in the reactivity series

Answer 1

Potassium
Sodium
Calcium
Magnesium
Aluminium
(Carbon)
Zinc
Iron
Lead
(Hydrogen)
Copper

Question 2

List two chemical properties of metals

Answer 2

1. They form positive ions

2. They react with acids to form a salt and hydrogen gas

Question 3

What is an alloy?

Answer 3

A mixture of a metal with another element.

Question 4

What are some of the benefits of alloys?

Answer 4

1. They are generally harder because the atoms in an alloy are of different sizes, meaning that the layers of atoms cannot slide over each other like they normally would.
2. They can be made so that they have a lower or higher melting point.

Question 5

Which metals will react with water?

Answer 5

Potassium down to calcium on the reactivity series.

Question 6

What is produced when a metal reacts with water?

Answer 6

A metal hydroxide and hydrogen gas.

Ex. Ca + H20 –> Ca(OH)2 + H2

Question 7

Which metals will react with steam?

Answer 7

Magnesium down to iron on the reactivity series.

Question 8

What is produced when a metal reacts with steam?

Answer 8

A metal oxide and hydrogen gas.

Ex. Mg + H20 –> MgO + H2

Question 9

Which metals will react with dilute acids?

Answer 9

Potassium down to iron on the reactivity series.

Note: lead will react slowly but then stop as an unreactive layer will be formed on its surface.

Question 10

What is produced when a metal reacts with a dilute acid?

Answer 10

A salt and hydrogen gas.

Ex. Zn + 2H+ –> H2 + Zn2+(aq)

Question 11

How is the reactivity series determined?

Answer 11

By a metal’s tendency to form its positive ion as an aqueous ion or as its oxide.

Question 12

What effect does heat have on a metal hydroxide?

Answer 12

K and Na will remain stable but all the other metals will decompose to their oxide and water.

Question 13

What effect does heat have on a metal carbonate?

Answer 13

They will all decompose to their oxide and carbon dioxide.

Question 14

What effect does heat have a metal nitrate?

Answer 14

Potassium and sodium will react to form a metal nitrous and oxygen gas.
Calcium down to copper will react to form their oxide, nitrogen dioxide and oxygen gas.
Everything below copper will react to form a metal, nitrogen dioxide and oxygen gas.

Question 15

Why does aluminium appear to be initially unreactive?

Answer 15

Because it has an unreactive aluminium oxide layer which takes time to wear away.

Question 16

How can a metal be obtained from its ore?

Answer 16

By displacing the metal from a solution of its ions by another metal higher on the reactivity series.

Question 17

Which metal OXIDES can be reduced by carbon?

Answer 17

Lower than and including zinc on the reactivity series.

Question 18

How is iron extracted from its ore and what are the essential reactions that take place?

Answer 18

1. Iron oxide, carbon and limestone are added into the top of a furnace.
2. Air is fed into the bottom of the furnace, reacting with carbon (C + O2 –> CO2).
3. This further reacts to form carbon monoxide (CO2 + C –> 2CO).
4. The carbon monoxide acts as the reducing agent (Fe3O4 + CO –> 3Fe + CO2).
5. The limestone decomposes in the heat (CaCO3 –> CaO + CO2) to calcium oxide and CO2. The CaO forms a slag with the impurities.
6. The iron (called pig iron and about 5% carbon) is tapped off at the bottom of the furnace.

Question 19

How is iron converted into steel?

Answer 19

Oxygen is blown through the molten pig iron to lower the carbon content and other elements are added to give the steel certain properties.

Question 20

Which process is aluminium extracted by?

Answer 20

From its ore bauxite by electrolysis.

Question 21

How is zinc extracted?

Answer 21

Zinc is extracted from zinc blende/zinc sulfide.

1. The ore is concentrated.
2. The zinc sulfide is heated in a furnace to form zinc oxide (2ZnS + 3O2 –> 2ZnO + 2SO2).
3. The zinc oxide is then heated in a furnace with carbon and reduced to zinc metal (ZnO + C –> Zn + CO).