Metals, Electrochemistry, Energetics and The Periodic Table

An iron nail is added to aqueous copper(II) sulfate and a different iron nail is added to aqueous magnesium sulfate.

The results are shown.

Which statement is correct?

• Copper atoms are oxidised more easily than magnesium atoms.

• Copper atoms are reduced more easily than iron ions.

• Iron atoms are oxidised more easily than copper atoms.

• Iron atoms are reduced more easily than copper ions.

Which statement about electrolysis is correct?

• Electrons move through the electrolyte from the cathode to the anode.

• Electrons move in the external circuit towards the cathode.

• Negative ions move in the external circuit towards the anode.

• Positive ions move through the electrolyte towards the anode.

Aqueous copper(II) sulfate is electrolysed using copper electrodes. What is the half-equation for the reaction at the cathode?

• 2H⁺ + 2e^– → H₂

• 4OH^– → O₂ + 2H₂O + 4e^-

• Cu → Cu²⁺ + 2e^-

• Cu²⁺ + 2e^– → Cu

Three statements about activation energy, Ea, are listed.

1) Colliding particles must have at least Eabefore they can react.

2) Ea for exothermic reactions is always greater than for endothermic reactions.

3) Ea is always endothermic.

Which statements are correct?

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Lithium and potassium are metals in Group I of the Periodic Table.

Lithium has a melting point of 181°C and a density of 0.53g/cm³.

Which row describes the melting point and density of potassium?

• A

• B

• C

• D

Which statements about transition elements are correct?

1) They have a low density.

2) They form ions with variable oxidation numbers.

3) They have a high melting point.

4) They form only colourless compounds.

• 1 and 2

• 1 and 4

• 2 and 3

• 3 and 4

Which statements describe the elements in Group VIII of the Periodic Table?

1) Their atoms have full outer electron shells.

2) They are unreactive metals.

3) They are monatomic gases.

4) They are diatomic gases.

• 1 and 3

• 1 and 4

• 2 and 3

• 2 and 4

Four metals, Q, R, S and T, are each added to separate samples of water, steam and dilute hydrochloric acid.

The results are shown.

Which statements are correct?

1) R is the least reactive metal.

2) T could be potassium.

3) S is more reactive than Q and R.

4) Metals generally react faster with steam than they react with water.

• 1, 2 and 4

• 1 and 2 only

• 2 and 3 only

• 3 and 4 only

Metal X acts as a sacrificial metal to prevent iron from corroding.

Metal X does not act as a sacrificial metal to prevent aluminium from corroding.

What is X?

• copper

• magnesium

• silver

• zinc

Which equation represents the reduction of a compound found in hematite in the blast furnace?

• 2Al₂O₃ → 4Al + 3O₂

• CaO + SiO₂ → CaSiO₃

• 2FeO + CO → Fe₂O₃ + C

• Fe₂O₃ + 3CO → 2Fe + 3CO₂