Define the term electrolyte .

An electrolyte is a liquid or solution that can conduct electricity — typically a molten ionic compound or an ionic compound dissolved in water.

Why can ionic compounds conduct electricity when molten or dissolved, but not when solid?

Ionic compounds can conduct electricity when molten or dissolved because their ions are free to move and carry charge. In the solid state the ions are held in fixed positions in the lattice and cannot move.

Define the term anode in an electrolysis cell.

The anode is the positive electrode in an electrolysis cell. Negatively charged ions ( anions ) migrate towards it.

True or False? Covalent compounds can be used as electrolytes.

False. Covalent compounds cannot conduct electricity because they have no free ions , so they cannot undergo electrolysis .

In which direction do positive ions move during electrolysis?

Positive ions move towards the cathode (the negative electrode) during electrolysis.

During electrolysis, .......... ions migrate to the cathode and .......... ions migrate to the anode.

During electrolysis, positive ions migrate to the cathode and negative ions migrate to the anode.

When molten lead(II) bromide is electrolysed, what product forms at the cathode and what forms at the anode?

At the cathode , lead metal is produced. At the anode , bromine gas is produced. The positive lead ions migrate to the cathode and the negative bromide ions migrate to the anode.

True or False? When a binary ionic compound is electrolysed in the molten state, the cathode product is always the metal.

True. In a molten binary ionic compound the positive metal ion always migrates to the cathode , where it gains electrons to form the metal.

Why must electrodes used in electrolysis be inert?

Electrodes must be inert (e.g. graphite or platinum) so they do not take part in side reactions with the electrolyte and do not affect the products of electrolysis.

What additional ions are always present in the electrolysis of an aqueous solution, and where do they come from?

H + and OH – ions are always present because water also contains small amounts of these ions. These ions must be considered alongside the ions from the dissolved compound.

State the rule that determines which ion is discharged at the cathode in the electrolysis of an aqueous solution.

The least reactive positive ion is discharged at the cathode . If the metal ion is above hydrogen in the reactivity series, hydrogen gas is produced instead of the metal.

True or False? In the electrolysis of aqueous copper sulfate solution, hydrogen gas is produced at the cathode.

False. Copper is below hydrogen in the reactivity series , so Cu 2+ ions are discharged at the cathode and copper metal is deposited, not hydrogen gas.

In the electrolysis of an aqueous solution, when is oxygen produced at the anode rather than a halogen?

Oxygen is produced at the anode when no halide ions (Cl – , Br – or I – ) are present. The OH – ions from water are then discharged at the anode instead.

If a metal is .......... hydrogen in the reactivity series, .......... gas is produced at the cathode during electrolysis of its aqueous salt.

If a metal is above hydrogen in the reactivity series, hydrogen gas is produced at the cathode during electrolysis of its aqueous salt.

What is the key difference between an inert electrode and a non-inert electrode in electrolysis?

An inert electrode (e.g. graphite) does not take part in the electrolysis reaction — it only provides a surface. A non-inert electrode reacts during electrolysis and changes the products formed.

In the purification of copper by electrolysis, what are the anode, cathode and electrolyte made of?

The anode is impure copper, the cathode is pure copper and the electrolyte is copper(II) sulfate solution. Copper dissolves from the anode and deposits on the cathode.

True or False? During electroplating, the object to be coated is connected as the cathode.

True. The object to be coated is the cathode . Metal ions from the electrolyte gain electrons at the cathode and are deposited as a thin metal layer on its surface.

In electroplating, what must the electrolyte contain?

The electrolyte must contain ions of the metal that is being used to coat the object. This ensures that the correct metal is deposited on the cathode during the process.

In electroplating, the .......... is the object you want to coat and the .......... is the metal you want to coat it with.

In electroplating, the cathode is the object you want to coat and the anode is the metal you want to coat it with.

Define oxidation in terms of electrons.

Oxidation is the loss of electrons by a substance during a chemical reaction.

Define reduction in terms of electrons.

Reduction is the gain of electrons by a substance during a chemical reaction.

At which electrode does oxidation occur during electrolysis, and why?

Oxidation occurs at the anode (positive electrode). Negative ions migrate to the anode and lose electrons to form neutral substances.

True or False? Positive ions gain electrons at the cathode during electrolysis.

True. Positive ions migrate to the cathode ( negative electrode ) and gain electrons to become neutral atoms or molecules. This is a reduction reaction .

At the anode, ions .......... electrons and are .......... . At the cathode, ions .......... electrons and are .......... .

At the anode, ions lose electrons and are oxidised . At the cathode, ions gain electrons and are reduced .

What happens to ions when they reach an electrode during electrolysis?

When ions reach an electrode they either lose or gain electrons to become neutral substances . These neutral substances are then discharged as the products of electrolysis.

How can you use the charge on an ion to remember whether it loses or gains electrons at an electrode?

Positive ions need to gain electrons (positive + negative = neutral) so they are reduced at the cathode. Negative ions need to lose electrons to become neutral so they are oxidised at the anode.

True or False? Both oxidation and reduction occur simultaneously during electrolysis.

True. Oxidation happens at the anode and reduction happens at the cathode at the same time, making electrolysis a redox process.

What two things must be balanced in a half equation?

Both the number of atoms/ions and the charges on each side of the half equation must be balanced.

Explain what a half equation represents in electrolysis.

A half equation shows the oxidation or reduction reaction at a single electrode — it includes the ion or atom and the electrons lost or gained to form the product.

In the electrolysis of molten lead(II) bromide, the half equation at the cathode is: Pb 2+ + .......... ⟶ ..........

In the electrolysis of molten lead(II) bromide, the half equation at the cathode is: Pb 2+ + 2e – ⟶ Pb Lead ions gain two electrons and are reduced to lead metal.

In the electrolysis of molten lead(II) bromide, what is the half equation at the anode?

At the anode the half equation is: 2Br – ⟶ Br 2 + 2e – Bromide ions lose electrons and are oxidised to bromine gas.

True or False? In the electrolysis of molten aluminium oxide, the half equation at the cathode is: Al 3+ + 3e – ⟶ Al

True. Aluminium ions gain three electrons at the cathode and are reduced to aluminium metal , which collects at the bottom of the cell.

In the electrolysis of molten aluminium oxide, what is the half equation for the reaction at the anode?

At the anode the half equation is: 2O 2– ⟶ O 2 + 4e – Oxide ions lose electrons and are oxidised to oxygen gas.

How do you determine whether a half equation represents oxidation or reduction?

If electrons appear on the left (are gained), the process is reduction . If electrons appear on the right (are lost), the process is oxidation .

True or False? Half equations are only required at Higher Tier for OCR GCSE Chemistry A.

True. Half equations are a Higher Tier only topic. Foundation Tier students are not required to write or interpret half equations .

A half equation at the anode always shows ions .......... electrons, which means the ions are .......... .

A half equation at the anode always shows ions losing electrons, which means the ions are oxidised .

GCSEChemistryOCRChemistry A (Gateway)Flashcards3. Chemical ReactionsElectrolysis

Electrolysis (OCR GCSE Chemistry A (Gateway)): Flashcards

Exam code: J248

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Define the term electrolyte.

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Cards in this collection (36)

Define the term electrolyte.
An electrolyte is a liquid or solution that can conduct electricity — typically a molten ionic compound or an ionic compound dissolved in water.
Why can ionic compounds conduct electricity when molten or dissolved, but not when solid?
Ionic compounds can conduct electricity when molten or dissolved because their ions are free to move and carry charge. In the solid state the ions are held in fixed positions in the lattice and cannot move.
Define the term anode in an electrolysis cell.
The anode is the positive electrode in an electrolysis cell. Negatively charged ions (anions) migrate towards it.
True or False?
Covalent compounds can be used as electrolytes.
False.
Covalent compounds cannot conduct electricity because they have no free ions, so they cannot undergo electrolysis.
In which direction do positive ions move during electrolysis?
Positive ions move towards the cathode (the negative electrode) during electrolysis.
During electrolysis, .......... ions migrate to the cathode and .......... ions migrate to the anode.
During electrolysis, positive ions migrate to the cathode and negative ions migrate to the anode.
When molten lead(II) bromide is electrolysed, what product forms at the cathode and what forms at the anode?
At the cathode, lead metal is produced. At the anode, bromine gas is produced. The positive lead ions migrate to the cathode and the negative bromide ions migrate to the anode.
True or False?
When a binary ionic compound is electrolysed in the molten state, the cathode product is always the metal.
True.
In a molten binary ionic compound the positive metal ion always migrates to the cathode, where it gains electrons to form the metal.
Why must electrodes used in electrolysis be inert?
Electrodes must be inert (e.g. graphite or platinum) so they do not take part in side reactions with the electrolyte and do not affect the products of electrolysis.
What additional ions are always present in the electrolysis of an aqueous solution, and where do they come from?
H⁺ and OH^– ions are always present because water also contains small amounts of these ions. These ions must be considered alongside the ions from the dissolved compound.
State the rule that determines which ion is discharged at the cathode in the electrolysis of an aqueous solution.
The least reactive positive ion is discharged at the cathode. If the metal ion is above hydrogen in the reactivity series, hydrogen gas is produced instead of the metal.
True or False?
In the electrolysis of aqueous copper sulfate solution, hydrogen gas is produced at the cathode.
False.
Copper is below hydrogen in the reactivity series, so Cu²⁺ ions are discharged at the cathode and copper metal is deposited, not hydrogen gas.
In the electrolysis of an aqueous solution, when is oxygen produced at the anode rather than a halogen?
Oxygen is produced at the anode when no halide ions (Cl^–, Br^– or I^–) are present. The OH^– ions from water are then discharged at the anode instead.
If a metal is .......... hydrogen in the reactivity series, .......... gas is produced at the cathode during electrolysis of its aqueous salt.
If a metal is above hydrogen in the reactivity series, hydrogen gas is produced at the cathode during electrolysis of its aqueous salt.
What is the key difference between an inert electrode and a non-inert electrode in electrolysis?
An inert electrode (e.g. graphite) does not take part in the electrolysis reaction — it only provides a surface. A non-inert electrode reacts during electrolysis and changes the products formed.
In the purification of copper by electrolysis, what are the anode, cathode and electrolyte made of?
The anode is impure copper, the cathode is pure copper and the electrolyte is copper(II) sulfate solution. Copper dissolves from the anode and deposits on the cathode.
True or False?
During electroplating, the object to be coated is connected as the cathode.
True.
The object to be coated is the cathode. Metal ions from the electrolyte gain electrons at the cathode and are deposited as a thin metal layer on its surface.
In electroplating, what must the electrolyte contain?
The electrolyte must contain ions of the metal that is being used to coat the object. This ensures that the correct metal is deposited on the cathode during the process.
In electroplating, the .......... is the object you want to coat and the .......... is the metal you want to coat it with.
In electroplating, the cathode is the object you want to coat and the anode is the metal you want to coat it with.
Define oxidation in terms of electrons.
Oxidation is the loss of electrons by a substance during a chemical reaction.
Define reduction in terms of electrons.
Reduction is the gain of electrons by a substance during a chemical reaction.
At which electrode does oxidation occur during electrolysis, and why?
Oxidation occurs at the anode (positive electrode). Negative ions migrate to the anode and lose electrons to form neutral substances.
True or False?
Positive ions gain electrons at the cathode during electrolysis.
True.
Positive ions migrate to the cathode (negative electrode) and gain electrons to become neutral atoms or molecules. This is a reduction reaction.
At the anode, ions .......... electrons and are .......... . At the cathode, ions .......... electrons and are .......... .
At the anode, ions lose electrons and are oxidised. At the cathode, ions gain electrons and are reduced.
What happens to ions when they reach an electrode during electrolysis?
When ions reach an electrode they either lose or gain electrons to become neutral substances. These neutral substances are then discharged as the products of electrolysis.
How can you use the charge on an ion to remember whether it loses or gains electrons at an electrode?
Positive ions need to gain electrons (positive + negative = neutral) so they are reduced at the cathode. Negative ions need to lose electrons to become neutral so they are oxidised at the anode.
True or False?
Both oxidation and reduction occur simultaneously during electrolysis.
True.
Oxidation happens at the anode and reduction happens at the cathode at the same time, making electrolysis a redox process.
What two things must be balanced in a half equation?
Both the number of atoms/ions and the charges on each side of the half equation must be balanced.
Explain what a half equation represents in electrolysis.
A half equation shows the oxidation or reduction reaction at a single electrode — it includes the ion or atom and the electrons lost or gained to form the product.
In the electrolysis of molten lead(II) bromide, the half equation at the cathode is: Pb²⁺ + .......... ⟶ ..........
In the electrolysis of molten lead(II) bromide, the half equation at the cathode is: Pb²⁺ + 2e^– ⟶ Pb
Lead ions gain two electrons and are reduced to lead metal.
In the electrolysis of molten lead(II) bromide, what is the half equation at the anode?
At the anode the half equation is: 2Br^– ⟶ Br₂ + 2e^–
Bromide ions lose electrons and are oxidised to bromine gas.
True or False?
In the electrolysis of molten aluminium oxide, the half equation at the cathode is: Al³⁺ + 3e^– ⟶ Al
True.
Aluminium ions gain three electrons at the cathode and are reduced to aluminium metal, which collects at the bottom of the cell.
In the electrolysis of molten aluminium oxide, what is the half equation for the reaction at the anode?
At the anode the half equation is: 2O^2– ⟶ O₂ + 4e^–
Oxide ions lose electrons and are oxidised to oxygen gas.
How do you determine whether a half equation represents oxidation or reduction?
If electrons appear on the left (are gained), the process is reduction. If electrons appear on the right (are lost), the process is oxidation.
True or False?
Half equations are only required at Higher Tier for OCR GCSE Chemistry A.
True.
Half equations are a Higher Tier only topic. Foundation Tier students are not required to write or interpret half equations.
A half equation at the anode always shows ions .......... electrons, which means the ions are .......... .
A half equation at the anode always shows ions losing electrons, which means the ions are oxidised.

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