IGCSE _0620_ELECTROCHEMISTRY

Multiple Choice

An electrolytic cell uses electrical energy to drive

• chemical reaction

• physical reaction

• no reaction

• none of above

Multiple Choice

An oxidizing agent will

• increase in mass

• lose electrons

• be reduced

• increase in oxidation number

Multiple Choice

If acidified potassium dichromate(VI) (K₂Cr₂O₇) acts as oxidizing agent, color changes from

• orange to red

• orange to green

• yellow to green

• yellow to red

Multiple Choice

What is a half-reaction?

• It is a reaction at equilibrium where half of the substances are reactants and half of the substances are products.

• It is the reaction that occurs when the switch of a galvanic cell is open.

• It shows EITHER the reduction component or the oxidation component of a redox reaction.

• It shows BOTH the reduction and oxidation components of a redox reaction.

Multiple Choice

What is a reducing agent?

• It is the species that gets reduced -- gains electrons.

• It is the species that gets oxidized -- loses electrons.

• It is the species that creates electrons.

• It is the species that destroys electrons.

Multiple Choice

Oxidation-reduction reactions occur because of the competition between particles for

• electrons

• positrons

• protons

• neutrons

Multiple Choice

Pb + 2Ag⁺ → Pb⁺² + 2Ag

The chemical species being reduced is

• Ag

• Pb

• Pb⁺²

• Ag⁺

Multiple Choice

What is reduction?

• It is the gain of electrons.

• It is the loss of electrons.

• It is the creation of electrons.

• It is the destruction of electrons.

Multiple Choice

The reaction 2NaCl → 2Na + Cl₂ is an example of

• a reduction reaction, only

• both an oxidation and reduction reaction

• an oxidation reaction, only

• neither an oxidation nor a reduction reaction

Multiple Choice

What is oxidation?

• It is the gain of electrons.

• It is the loss of electrons.

• It is the creation of electrons.

• It is the destruction of electrons.

Multiple Choice

What is an anode?

• It is the electrode where oxidation takes place.

• It is the electrode where reduction takes place.

• It is an aqueous solution containing an electrode.

• It is the salt bridge that connects half-cells.

Multiple Choice

In the reactions

Sn⁺² + 2Fe⁺³ → Sn⁺⁴ + 2Fe⁺²

the oxidizing agent is

• Sn⁺⁴

• Sn⁺²

• Fe⁺³

• Fe⁺²

Multiple Choice

What is an oxidizing agent?

• It is the species that gets reduced -- gains electrons.

• It is the species that gets oxidized -- loses electrons.

• It is the species that creates electrons.

• It is the species that loses electrons.

Multiple Choice

What is a cathode?

• It is the electrode where oxidation takes place.

• It is the electrode where reduction takes place.

• It is an aqueous solution containing an electrode.

• It is the salt bridge that connects half-cells.

Multiple Choice

In the reactions

Sn⁺² + 2Fe⁺³ --> Sn⁺⁴ + 2Fe⁺²,

the reducing agent is

• Fe⁺³

• Sn⁺²

• Sn⁺⁴

• Fe⁺²

Multiple Choice

In a redox reaction, the species that loses electrons

• is called the cathode

• is oxidized

• gains mass at the electrode

• decreases in oxidation number

Multiple Choice

In electrolysis of copper purification, at cathode

• pure copper gets deposited

• the object to be electroplated is kept

• impure copper gets deposited

• CuSO₄ gets deposited

Multiple Choice

What is a redox reaction?

• A reaction where both reactants get reduced.

• A reaction where both reactants get oxidized.

• A reaction that involves a transfer of electrons between reactants.

• A reaction that involves the combustion of at least one reactant.

Multiple Choice

Mg + PbCl₂ → MgCl₂ + Pb

Which statement correctly describes the oxidation and reduction that occur?

• Mg is oxidized and Pb⁺² is reduced

• Mg is oxidized and Cl^- is reduced

• Mg is reduced and Cl^- is oxidized

• Mg is reduced and Pb⁺² is oxidized

Multiple Choice

When water is electrolyzed, gas collected at cathode, is

• sulphur

• oxygen

• hydrogen

• sulphur dioxide

Multiple Choice

In electrolysis, particles which move towards cathode are called

• anions

• cations

• photons

• positrons

Multiple Choice

The diagram shows a failed attempt to copper-plate a pan.

Which action will plate the pan with copper?

• cooling the copper sulfate solution in an ice bath

• heating the copper sulfate solution to boiling point

• increasing the voltage from 3V to 6V

• making the pan the cathode and the copper the anode

Multiple Choice

The diagram shows the electroplating of a steel object.

A student made the following statements.

1. The object turns a reddish-brown colour.

2. The copper sulfate solution changes to a paler blue colour.

3. The copper electrode becomes smaller.

Which statements are correct?

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Multiple Choice

Which metal could not be used for electroplating by using an aqueous solution?

• chromium

• copper

• silver

• sodium

Multiple Choice

Which products are formed at the anode and cathode when electricity is passed through molten

lead(II) bromide?

• A

• B

• C

• D

Multiple Choice

The diagram shows an electrical cable.

Which statement about the substances used is correct?

• The coating is plastic because it conducts electricity well.

• The core is copper because it conducts electricity well.

• The core is copper because it is cheap and strong.

• The core is iron because it is cheap and strong.

Multiple Choice

The diagram shows apparatus used in an attempt to electroplate a metal ring with copper.

The experiment did not work.

What change is needed in the experiment to make it work?

• Add solid copper(II) sulfate to the electrolyte.

• Increase the temperature of the electrolyte.

• Replace the copper electrode by a carbon electrode.

• Reverse the connections to the battery.

Multiple Choice

Substance X was electrolysed in an electrolytic cell.

A coloured gas was formed at the anode and a metal was formed at the cathode.

What is substance X?

• aqueous sodium chloride

• molten lead bromide

• molten zinc oxide

• solid sodium chloride

Multiple Choice

The diagram shows apparatus for plating a spoon with silver.

Which statement is not correct?

• Silver would stick to the spoon because it is a very reactive metal.

• The metal electrode would be made from silver.

• The spoon would be connected to the negative of the power supply.

• The electrolyte would be a silver salt dissolved in water.

Multiple Choice

Three electrolysis cells are set up. Each cell has inert electrodes.

The electrolytes are listed below.

Cell 1 - aqueous sodium chloride

Cell 2 - concentrated hydrochloric acid

Cell 3 - molten lead(II) bromide

In which cells is a gas formed at both electrodes?

• 1 and 2

• 1 and 3

• 2 only

• 3 only

Multiple Choice

The diagram shows how aluminium is manufactured by electrolysis.

What are the anode and cathode made of?

• anode - aluminium / cathode - aluminium

• anode - aluminium / cathode - graphite

• anode - graphite / cathode - aluminium

• anode - graphite / cathode - graphite

Multiple Choice

Which statement about electroplating iron with chromium is correct?

• A catalyst is used.

• The anode is chromium.

• The electrolyte contains aqueous iron ions.

• The electrolyte contains solid chromium ions.

Multiple Choice

Which statement describes what happens during electrolysis?

• Covalent compounds produce more complex substances.

• Covalent compounds produce simpler substances.

• Ionic compounds produce more complex substances.

• Ionic compounds produce simpler substances.

Multiple Choice

Aqueous copper (II) sulfate is electrolysed using carbon electrodes.

What is produced at each electrode?

• A

• B

• C

• D

Multiple Choice

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

Multiple Choice

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

Multiple Choice

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

Multiple Select

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

Multiple Select

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

Multiple Choice

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

Multiple Choice

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 held in a lattice

• Electrical conductivity occurs throughout

  the whole experiment

Multiple Choice

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

Multiple Choice

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-

Multiple Choice

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

Multiple Choice

What is electrolysis?

• breaking down of a compound using a current
• making a compound using a current

Multiple Choice

The negatively charged ions (anions) are attracted to the ________.

• anode

• cathode

Multiple Choice

Anions get discharged by ________ electrons at the ___________

• gaining, cathode

• losing, anode

• gaining, anode

• losing, cathode

Multiple Choice

What ions are present in molten aluminium oxide?

• Al³⁺, O^2-, H⁺, OH^-

• Al³⁺, O^2-

• Al³⁺, OH^-

Multiple Choice

What is the name given to the solution that is being electrolysed?

• Salt solution
• Electric solution
• Mineral solution
• Electrolyte

Multiple Choice

Explain why the electrolyte has to be a liquid.

• So the ions can move
• So the electrons can move
• So that it doesn't get too hot
• So the fish are ok

Multiple Choice

___________ electrode is an inert electrode.

• Copper

• Iron

• Carbon

• Zinc

Multiple Choice

What particle carries the charge in the electrolyte?

• electron
• proton
• ion
• atom

Multiple Choice

What particle carries the charge in the wire?

• electron
• proton
• ion
• atom

Multiple Choice

What is the ore of aluminium called?

• Baxite

• Bauxite

• Cryolite

• Malachite

Multiple Choice

The electrodes in electrolysis of aluminium are made of

• Steel

• Anodes

• Graphite

• Plastic

Multiple Choice

What do you add to aluminium ore to reduce its melting temperature?

• Dendrite

• Malachite

• Bauxite

• Cryolite

Multiple Choice

When concentrated NaCl solution is electrolysed what has forms at the anode?

• Hydrogen
• Oxygen
• Chlorine
• Sodium

Multiple Choice

Different pairs of metals produce different voltages.

• True

• False

Multiple Choice

The closer the elements in the Electrochemical Series, the greater the voltage produced.

• True

• False

Multiple Choice

Electrons will flow from the element higher in the Electrochemical Series to the one lower in the Electrochemical Series.

• True

• False