Galvanic Cells

What is the purpose of an electrochemical cell

To convert chemical energy into electrical energy through redox reactions.

What connects the oxidation and reduction half-reactions in an electrochemical cell

An external circuit that allows electron flow from anode to cathode.

Where does oxidation occur in an electrochemical cell

At the anode.

Where does reduction occur in an electrochemical cell

At the cathode.

In a galvanic cell, what type of reaction generates electricity

a spontaneous redox reaction

Which electrode is negative in a galvanic cell

The anode.

Which electrode is positive in a galvanic cell

The cathode.

What does the salt bridge do

It allows ion movement between half-cells to maintain electrical neutrality.

What ions move through the salt bridge to the cathode

Cations.

What ions move through the salt bridge to the anode

Anions.

What happens at the anode during the Zn/Cu galvanic cell reaction

The zinc rod corrodes and its mass decreases.

What happens at the cathode during the Zn/Cu galvanic cell reaction

Copper is deposited and the mass of the copper rod increases.

What happens to the colour of Cu²⁺ solution during the Zn/Cu galvanic cell reaction

It becomes lighter as Cu²⁺ is reduced to copper metal.

What is the oxidation half-equation for zinc in a galvanic cell

Zn(s) → Zn²⁺(aq) + 2e⁻.

What is the reduction half-equation for copper in a galvanic cell

Cu²⁺(aq) + 2e⁻ → Cu(s).

Why does a voltmeter give a positive reading in a galvanic cell

Because the redox reaction is spontaneous and generates a potential difference.

What happens when a copper wire is placed in silver nitrate solution

The solution turns more blue and silver is deposited on the copper wire.

Why are more reactive metals at the top of the reactivity series

They are stronger reducing agents and lose electrons more easily.

Why are less reactive metals lower in the reactivity series

They are weaker reducing agents and are less likely to oxidise.

What is an inert electrode

An unreactive electrode used when no metal rod is present in a half-cell.

Give two examples of inert electrodes

Platinum and graphite.

Write the half-equation for hydrogen at an inert electrode

2H⁺(aq) + 2e⁻ ⇌ H₂(g).

What happens to the zinc electrode in a Zn/Cu galvanic cell

It corrodes and its mass decreases as Zn is oxidised.

What happens to the copper electrode in a Zn/Cu galvanic cell

Its mass increases as Cu²⁺ ions are reduced and deposited as copper metal.

What happens to the Cu²⁺ solution during the reaction

It becomes lighter in colour as Cu²⁺ is reduced to copper metal.

What happens to the Zn²⁺ solution during the reaction

Its concentration increases as Zn(s) is oxidised to Zn²⁺(aq).

Which direction do electrons flow in a Zn/Cu galvanic cell

From the zinc anode to the copper cathode through the external circuit.

What happens when a copper wire is placed in silver nitrate solution

Silver crystals deposit on the copper wire and the solution turns more blue.

Why does the solution turn blue in the Cu/Ag reaction

Because Cu is oxidised to Cu²⁺(aq) while Ag⁺ is reduced to Ag(s).

What happens to the mass of the copper electrode in the Cu/Ag reaction

It decreases as copper is oxidised.

What happens to the mass of the silver metal in the Cu/Ag reaction

It increases as silver is deposited.

What visible evidence indicates a redox reaction in these galvanic systems

Electrode mass changes and colour changes in the solution.

In a Zn/Cu galvanic cell, which electrode is the anode?

Zinc

In a Zn/Cu galvanic cell, which electrode is the cathode?

copper

What half-reaction occurs at the zinc anode

Zn(s) → Zn²⁺(aq) + 2e⁻.

What half-reaction occurs at the copper cathode

Cu²⁺(aq) + 2e⁻ → Cu(s).

Why is zinc the anode in the Zn/Cu cell

Zinc is more reactive and oxidises more readily than copper.

In a Cu/Ag galvanic cell, which electrode is the anode?

copper

In a Cu/Ag galvanic cell, which electrode is the cathode?

silver

What half-reaction occurs at the copper anode

Cu(s) → Cu²⁺(aq) + 2e⁻.

What half-reaction occurs at the silver cathode

2Ag⁺(aq) + 2e⁻ → 2Ag(s).

Why is silver the cathode in the Cu/Ag cell

Silver ions are reduced more readily than copper ions, so copper is oxidised

What is the main purpose of the salt bridge in a galvanic cell

To maintain electrical neutrality by allowing ions to move between the half-cells.

What happens if a galvanic cell does not have a salt bridge

The reaction stops as charge builds up and prevents further electron flow.

Which ions move toward the anode through the salt bridge

Anions.

Which ions move toward the cathode through the salt bridge

Cations.

Why do anions move toward the anode

To balance the positive charge building up as metal atoms are oxidised.

Why do cations move toward the cathode

To replace positive ions being reduced at the cathode.

What is the overall effect of ion movement in the salt bridge

It maintains charge balance between the half-cells.

How does the salt bridge complete the circuit

It allows ionic movement to complement the flow of electrons in the external circuit.

What is commonly used as a salt bridge in lab galvanic cells

A U-shaped tube containing an inert electrolyte such as KNO₃ or KCl.

Why must the salt bridge electrolyte be inert

So it doesn’t react with the solutions or interfere with the redox reactions in either half-cell.