Unit 3-Metals

Question 1

Every metal conducts electricity. Explain.

Answer 1

In metallic bonding, the outer electrons are delocalised (free to move). This means an electrical current can flow through metallic materials.

Question 2

What is the word equation for when metals react with water?

Answer 2

metal + water → metal hydroxide + hydrogen

Question 3

What are the word, balanced chemical and ionic equations when magnesium reacts with water?

Answer 3

magnesium + water → magnesium hydroxide + hydrogen

Mg + 2H₂O → Mg(OH)₂ + H₂

_​Mg(s) + 2H₂O → Mg²⁺(aq) + 2OH^-(aq) + H₂(g)

Question 4

What is the word equation for when metals react with oxygen?

Answer 4

metal + oxygen → metal oxide

Question 5

What are the word, balanced chemical and ionic equations when zinc (II) oxide is formed?

Answer 5

zinc+ oxygen → zinc (II) oxide

2Zn+ O₂ → 2ZnO

2Zn(s) + O₂(g) → 2Zn²⁺O^2-(s)

Question 6

What is the word equation for when metals react with acid?

Answer 6

metal + acid→ metal salt + hydrogen

Question 7

What are the word equation, balanced formula and ionic equations for lithium reacting with hydrochloric acid?

Answer 7

lithium + hydrochloric acid → lithium chloride + hydrogen

2Li + 2HCl → 2LiCl + H₂

2Li(s) + 2H⁺(aq) + 2Cl^{<span>-</span>}(aq)​ →​ 2Li⁺(aq) + 2Cl^{<span>-</span>}(aq) + H₂(g)

Without spectator ions

2Li(s) + 2H⁺(aq) →​ 2Li⁺(aq) + H₂(g)

Question 8

Describe how the following metals can be extracted from their ores.

1. Silver, Gold and Mercury
2. Copper, Lead and Iron
3. Aluminium, sodium and potassium

Answer 8

1. Unreactive metals can be extracted by heat alone.
2. Metals in the middle of the electrochemical series can be extracted by heating with carbon or carbon monoxide.
3. Reactive metals must undergo electrolysis (using a direct current (DC supply) to be extracted.

Question 9

Describe how an electrochemical cell is set up.

Answer 9

A simple cell can be made by placing two metals in an electrolyte and connecting using wires.

Question 10

What is meant by a half cell?

Answer 10

Metals in solutions of their own ions. (Copper in copper sulphate)

Question 11

What name is given to the device used to link half cells and completes the circuit?

Answer 11

Ion bridge (salt bridge)

Question 12

Different pairs of metals produce different voltages.

How can we predict the size of voltage?

Answer 12

The further apart elements are in the electrochemical series, the greater the voltage produced.

Question 13

Do electrons flow from the higher metal in the ECS (electrochemical series) to the lower or lower to highest?

Answer 13

Higher to lower.

Question 14

What word is used to describe the reaction where a metal has lost electrons?

Answer 14

Oxidation is loss.

Question 15

What word is used to describe the reaction where a metal has gained electrons?

Answer 15

Reduction is gain of electrons.

Question 16

What happens in a redox equation?

Answer 16

In a redox reaction, reduction and oxidation take place at the same time.

Question 17

Na(s) –> Na⁺(aq) + e^-

Is this an oxidation or a reduction equation?

Answer 17

Oxidation.

Question 18

Cu²⁺(aq) + 2e^- –> Cu(s)

Is this an oxidation or a reduction equation?

Answer 18

Reduction

Question 19

Li(s) –> Li⁺(aq) + e^-

Ag⁺(aq) + e^- –> Ag(s)

What would the overall redox equation be for the above reactions?

Answer 19

Li(s) + Ag⁺(aq) –> Li⁺(aq) + Ag(s)

Question 20

Combine these half equations

Na(s) –> Na⁺(aq) + e^-

Cu²⁺(aq) + 2e^- –> Cu(s)

Answer 20

2Na(s) + Cu²⁺(aq)–> 2Na⁺(aq) + Cu(s)