Electrochemistry

Diagram shows an electrolysis cell.

Which of the substances cause the bulb to light up when electricity passes through it?

• Ethanol

• Dilute ethanoic acid

• Solid lead(II) bromide

• Tetrachloromethane

What are the products formed at the anode and the cathode during the electrolysis of molten magnesium oxide using carbon electrodes?

• Anode: Oxygen

  Cathode: Magnesium

• Anode: Magnesium

  Cathode: Oxygen

• Anode: Hydrogen

  Cathode: Oxygen

• Anode: Oxygen

  Cathode: Hydrogen

Table shows information about three chemical cells.

What is the possible potential difference of the chemical cell when metal Z is paired with W ?

• 0.3 V

• 1.2 V

• 1.5 V

• 2.1 V

Diagram shows the electrolysis of concentrated copper(II) chloride solution using carbon as electrodes.

Which of the followings is the correct half equations represents the reactions at the anode?

• 4OH^- → 2H₂O + O₂ + 4e

• 2Cl^- → Cl₂ + 2e

• Cu → Cu²⁺ + 2e

• Cu²⁺ + 2e → Cu

Diagram

shows the apparatus set-up for the electrolysis of 1.0 mol dm ^-3 sodium chloride solution using carbon electrodes.Which of the following are the observation for the electrolysis process shown in Diagram?

• Grey solid deposited on electrode B

• Colourless gas is released at electrode B

• Carbon electrode A becomes thinner

• Greenish yellow gas is released at electrode A

Molten X is electrolysed using carbon electrodes. After 10 minutes, a brown solid is deposited on the cathode and a brown gas is released at the anode. What is molten X?

• Lead(II) chloride

• Lead(II) bromide

• Copper(II) chloride

• Copper(II) bromide

Table shows the results of the electrolysis of molten lead (II) bromide.

The ammeter only shows reading when solid lead (II) bromide, PbBr₂ is completely melted. Which of the following explains the observation?

• Bromide ions receive electrons to form bromine gas

• Lead (II) ions donate electrons to produce lead metal

• In the solid state, bromide and lead (II) ions are in fixed position

• Electrical conductivity occurs throughout

  the whole experiment

Which of the following reactions shows that copper is oxidized?

• Reaction of magnesium with copper (II)

  oxide

• Reaction of copper with silver nitrate solution

• Electrolysis of copper (II) nitrate

  solution by using carbon nitrate

• Voltaic cell with copper and magnesium

  electrodes in dilute sulphuric acid

Diagram shows an electrolysis of dilute sulphuric acid.

What could be gas X and the half-equation occurring at the cathode?

• Carbon dioxide, C + O₂ → CO₂

• Hydrogen, 2H⁺ + 2e —>H₂

• Oxygen, 4OH^- → H₂O + O₂ + 4e-

• Sulphur dioxide, SO₄ ^2- → SO₂ + O₂ + 2e-

Diagram shows an apparatus set-up for a chemical cell. What can you observed from this experiment?

• Hydrogen gas is liberated at the copper plate

• Magnesium electrode becomes thinner

• Colourless solution turns to brown

• Electron flows from magnesium to the copper plate