Electrolysis

Which English chemist is associated with the discovery of sodium and potassium in 1807, using a new method of electrolysis?
1. Humphry Davy
2. John Dalton
3. Joseph Priestley
4. Michael Faraday
Which one of the following statements is NOT correct?
1. The electrolyte only conducts when in the molten state.
2. Electrodes that react with the electrolyte are said to be "active".
3. Ions must be present in the electrolyte in order that it conducts electricity.
4. Pure water does not allow a current to flow through it.
When an aqueous solution conducts electricity there is always
1. evidence of a chemical change.
2. a gas produced at one electrode.
3. a metal deposited at the cathode.
4. hydrogen or oxygen gas produced.
When an electric current is passed through a solution of potassium iodide (KI) containing some phenolphthalein indicator, a brown colour is observed at one of the electrodes.
Which one of the following reactions is occurring at this electrode?
1. 2I⁻ → I₂ + 2e⁻
2. KI + e⁻ → I⁻ + K
3. 2H₂O + 2e⁻ → H₂ + 2OH⁻
4. 2H₂O + 4I⁻ → 2I₂ + 2OH⁻ +H₂ + 2e⁻
In the electolysis of a solution of potassium iodide with phenolphthalein indicator, a pink colour appears at the negative electrode. Which one of the following is occurring?
1. Hydrogen gas is being produced at the cathode and iodine at the anode.
2. Oxygen gas is being produced at the cathode and iodine at the anode.
3. Hydrogen gas is being produced at the cathode and oxygen gas at the anode.
4. Iodine is being produced at the cathode and oxygen gas at the anode.
An electrolyte is a substance which conducts an electric current
1. and is also decomposed by it.
2. when it is in the molten state.
3. under any conditions.
4. when in the solid state.
In the electrolysis of an aqueous solution, which ONE of the following statements is NOT true?
1. Electrons flow around the circuit from the cathode to the negative end of the battery.
2. Reduction takes place at the cathode.
3. Oxidation takes place at the positive electrode.
4. Electrons are lost by one of the species at the anode.
What two species are the anions in a solution of copper sulfate?
1. Sulfate ions and hydroxide ions.
2. Copper ions and hydrogen ions.
3. Hydrogen ions and sulfate ions.
4. Copper ions and sulfate ions.
The Hofmann Voltameter is often used in the electrolysis of water. Which one of the following best describes what happens at the cathode?
1. 4H⁺ + 4e⁻ → 2H₂
2. 2H₂O → 4H⁺ + O₂ + 4e⁻
3. 2H₂O + 2e⁻ → H₂ + 2OH⁻
4. 2H₂O → 2H₂ + O₂
Universal indicator turns red in acidic solutions, green in neutral solutions and blue in alkaline solutions. If universal indicator is added to a solution of sodium sulfate being electrolysed, a red colour appears at the anode.
Which of the following reactions is taking place at the anode?
1. 2H₂O → O₂ + 4H⁺ + 4e⁻
2. 2H₂O + 2e⁻ → H₂ + 2OH⁻
3. 2H₂ + O₂ → 2H₂O
4. SO₄²⁻ → SO₂ + O₂ + 2e⁻
When copper sulfate solution is electrolysed using copper electrodes (i) the cathode loses some of its mass, (ii) the blue colour of the copper sulfate solution gets fainter (iii) the electrodes are said to be "active"
Which of the above statements is/are correct?
1. (ii) and (iii) only
2. (i) and (iii) only
3. (i) and (ii) only
4. (i) only
Electroplating takes place on
1. the cathode only.
2. the anode only.
3. both the anode and the cathode.
4. either the anode or the cathode.
Electroplating is used to coat one metal with a usually less reactive metal. When plating silver onto cutlery, which one of the following electrolytes would be the most suitable?
1. Silver nitrate (AgNO₃)
2. Copper sulfate (CuSO₄)
3. Molten silver (Ag)
4. Zinc sulfate (ZnSO₄)
In an electroplating experiment carried out by students in a school laboratory, the cathode used was made of steel. The electrolyte used was a solution of nickel sulfate.
What type of anode was most likely used in order to make the experiment a success?
1. Nickel
2. Iron
3. Carbon
4. Copper
The diagram shows an electric current being produced by a galvanic cell. Which one of the following statements is NOT correct?
1. Copper ions are produced at the copper electrode.
2. Zinc ions are produced at the zinc electrode.
3. The salt bridge maintains a balance between the ions in both parts of the cell.
4. The electrons flow through the wires from the zinc to the copper electrode.
In the electrolysis of aqueous potassium iodide (KI) using inert electrodes, which of the following occurs?
1. Water is reduced at the cathode.
2. Iodide ions are reduced at the anode.
3. Iodine forms at the cathode.
4. Potassium ions are reduced to potassium atoms.
When electroplating nickel with silver, which one of the following equations represents what happens at the cathode?
1. Ag⁺ + e⁻ → Ag
2. Ag → Ag⁺ + e⁻
3. Ni²⁺ + 2e⁻ → Ni
4. Ni → Ni²⁺ + 2e⁻
For the galvanic cell shown, which one of the following statements is correct?
1. The electrode potential is measured by the voltmeter.
2. Electrons flow from the zinc electrode to the magnesium electrode.
3. At the zinc electrode, zinc ions are formed.
4. The following reaction takes place at the magnesium electrode: Mg²⁺ + 2e^- → Mg
The electrochemical series lists the elements in order of their standard electric potentials.
Which one of the following is the correct order for decreasing reactivity of the metals?
1. Sodium, aluminium, lead, copper
2. Potassium, silver, magnesium, aluminium
3. Gold, copper, zinc, potassium
4. Mercury, calcium, sodium, magnesium
The electrode potential of a metal is obtained by comparing it with the half-cell of:
1. hydrogen
2. oxygen
3. nitrogen
4. gold
The electrochemical series is a list of elements in order of their
1. standard electrode potentials.
2. reactivity with other metals.
3. position in the activity series.
4. position in the Periodic Table.
Which one of the following would make a suitable inert electrode in the electrolysis of sodium sulfate solution?
1. Platinum
2. Copper
3. Silver nitrate
4. Sodium
In an experiment to show the displacement reaction of metals, a piece of zinc was placed in a solution of copper sulfate. Which one of the following does NOT happen?
1. Bubbles of hydrogen gas form on the zinc.
2. The copper sulfate solution gets paler in colour.
3. A brown solid is seen to form around the zinc.
4. The zinc metal corroded slowly.
If a solution of copper sulfate (CuSO₄) is electrolysed using copper (Cu) electrodes, then
1. the anode is oxidised and the cathode reduced.
2. the anode is reduced and the cathode is oxidised.
3. the anode is oxidised and copper forms at this anode.
4. the cathode is oxidised and copper forms at the cathode.
In the electrolysis of copper sulfate solution using copper electrodes, which one of the following reactions takes place at the cathode?
1. Cu²⁺ + 2e⁻ → Cu
2. Cu → Cu²⁺ + 2e⁻
3. 2H₂O + 2e⁻ → H₂O + 2OH⁻
4. 2H⁺ + 2e⁻ → H₂
In the electrolysis of acidified water, what is the correct equation for the reaction that takes place at the anode?
1. 2H₂O → 4H⁺ + O₂ + 4e⁻
2. 4H⁺ + 4e⁻ → 2H₂
3. 2H₂ + O₂ → 2H₂O
4. 2H₂O → 2H₂ + O₂
When a solution of sodium sulfate is electrolysed using universal indicator solution, what colours will appear at the cathode and the anode?
1. Purple at the cathode and red at the anode
2. Red at the cathode and purple at the anode
3. Brown at the cathode and red at the anode
4. Green at the cathode and brown at the anode
Phenolphthalein indicator is colourless in an acid and turns pink in an alkaline solution. When an aqueous solution of potassium iodide is electrolysed with phenolphthalein indicator, what colours appear at the electrodes?
Cathode: 2H₂O_(l) + 2e^- → H_(g) + 2OH^-_(aq)
Anode: 2I^-_(aq) → I_2(s) + 2e^-
1. Pink at the cathode and brown at the anode
2. Brown at the anode and colourless at the cathode
3. Brown at the cathode and pink at the anode
4. Red at the cathode and pink at the anode
Which one of the following is NOT a practical application of electrolysis?
1. Purifying steel
2. Plating silver onto nickel cutlery
3. Purifying copper
4. Plating steel with chromium
What electrolyte is used to electroplate silver onto a spoon?
1. Silver nitrate
2. Pure water
3. Copper sulfate
4. Acidified water
What is the name given to a solution, or liquid that conducts electricity?
1. Electrolyte
2. Anion
3. Cathode
4. Electrode
When water is electrolysed by adding dilute sulfuric acid into the Hofmann Voltameter, which one of the following statements is incorrect?
1. Cations are attracted to the positive anode.
2. The ratio of hydrogen:oxygen produced is 2:1
3. Dilute sulfuric acid is added to the water to improve its conductivity.
4. Hydrogen ions in the solution move towards the cathode
When an electric current is passed through an electrolyte, which of the following carries this current through the electrolyte?
1. Ions
2. Electrons
3. Atoms
4. Molecules
Dilute sulfuric acid is electrolysed using inert electrodes.
1. 1 mole of O₂ at the anode, 2 moles of H₂ at the cathode
2. 1 mole of H₂ at the anode, 2 moles of O₂ at the cathode
3. 2 moles of H₂ at the anode, 1 mole of O₂ at the cathode
4. 2 moles of O₂ at the anode, 1 mole of H₂ at the cathode
In the electrolysis of acidified water, if 8.4 cm³ of hydrogen gas is evolved, what volume of oxygen gas is evolved?
1. 4.2 cm³
2. 8.4 cm³
3. 12.6 cm³
4. 16.8 cm³
Which statement is correct for the electrolysis of a molten salt?
1. Both positive and negative ions move toward electrodes.
2. Positive ions move toward the positive electrode
3. A gas is produced at the negative electrode.
4. Only electrons move in the electrolyte.
Which of the folllowing are used for the electroplating of a metal spoon with copper?
1. An electrolyte containing aqueous copper(II) ions
2. A copper anode (positive electrode)
3. A copper cathode (negative electrode)
1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3
A metallic object is electroplated with copper using a solution of copper(II) sulfate.
Which one of the following statements is correct?
1. The reaction occurring at the negative electrode is Cu²⁺ + 2e⁻ → Cu.
2. The positive electrode increases in mass.
3. The concentration of Cu²⁺ ions in the solution decreases.
4. Reduction occurs at the positive electrode.

Electrolysis

Multiple Choice Quiz