Galvanic cells and the electrochemical series

Galvanic cell

A galvanic cell(primary cell) is an electrochemical cell that consists of two half-cells that are connected by a wire and salt  bridge to create a complete electric circuit

Spontaneous reactions

reactions that proceed on their own, without the need for any external supply

Converting chemical energy to thermal energy

A zinc strip is placed in copper (II) sulfate solution (CU2+ ions), the zinc is oxidised and electrons flow from the zinc metal to the copper ions.

This is a spontaneous reaction and requires no energy because it releases energy

What happens when the zinc dissolves?

Copper ions are reduced to copper metal and the original blue colour of the solution begins to fade. , then it becomes colourless

All the copper ions in the solution are reduced to form copper metal, and the zinc goes into the solution as zinc ions

How to convert chemical energy into electrical energy

A strip of zinc metal is placed in a beaker containing zinc sulfate solution. It is connected by a wire to a strip of copper placed in a beaker containing copper sulfate solution.

The wire proved a pathway for the electrons to pass from the zinc atoms to copper cations

The reaction cant occur because the circuit is not complete. How to complete the circuit

A salt bridge is needed to connect the two electrolytes

Salt bridge

A component that provides a supply of mobile ions that carry a charge through the solution of a galvanic cell during a reaction

Electrolytes

Liquids that can conduct electricty

How does a salt bridge work?

It can be a filter paper or a u tube with cotton wool in it

It is soaked in a salt solution, like KNO3 and it is used to connect the two peakers

KNO3

• The K⁺ and NO₃⁻ ions move through the solution to balance the charges happening at each electrode.

• This movement of charged particles (ions) is what allows current to flow in the liquid part of the circuit.

• Without ions moving, the circuit would break, and no current would flow.

How does ion movement in a galvanic cell help maintain electric neutrality in each beaker?

The movement of ions maintains electric neutrality by supplying opposite charges to each beaker:

• Anions (e.g., NO₃⁻) flow to the anode (first beaker), where Zn²⁺ ions are produced.

• Cations (e.g., K⁺) flow to the cathode (second beaker), where Cu²⁺ ions are reduced to copper atoms.

This movement balances the charges and allows the current to continue flowing.

What do the electrons and ions carry

Electrons carry the current in the wire from zinc to copper

ions carry the current in solution

Internal circuit

A circuit within a solution; anions flow to the anode and cations flow to the cathode

Half cell

half of a galvanic cell where either oxidation or reduction reactions takes place seperated from the other half cells

Electrodes

The metal strips used to conduct electricity in a galvanic cell

External circuit

A circuit composed of all the connected components within an electrolytic or a galvanic cell to achieve desired conditions

Solutions that can conduct a current

Electrolytes

the electrode at which oxidation occurs, has negative charge

Anode

The electrode at which reduction occurs, has positive charge

cathode

when constructing answers remember

The Internal circuit always involves Ions

The external circuit always involves Electrons

RedCat- Reduction occurs at the cathode

AnOx- Oxidation occurs at the anode

Electrochemical series

A cell generates electrical energy from chemical reactions

A metal ion-metal half-cell consists of

A metal rod in a solution of its ions, usually from the sulfate salf

A solution half cell

uses an inert (unreactive) electrode in the reacting solution.

Are electrons formed at the anode in a galvanic cell?

Yes. At the anode, oxidation occurs where metal atoms lose electrons, releasing (forming) electrons that flow through the circuit to the cathode.

The more reactive a metal is

The more likely it is to lose electrons and become a positive ion

What do the reversible arrows represent ina electrochemical series equation

It is possible for the positive ions to take back electrons and become metal again

Standard electrode potentials

The flow of electrons created by different half-cell combinations varies, and can be measured by a voltmeter. This is called the cell potential difference, cell potential or cell voltage

Voltmeter

A device used for measuring the potential differences between two points in a cirucit

Cell potential difference

The difference between the reduction potentials of two cells

electrical potential

the ability of a galvanic cell to produce an electrical current

standard electrode potential

voltage or potential difference due to the difference in charge on the electrode and electrolyte compared to the hydrogen half cell

reduction potential

a measure of the tendency of an oxidising agent to accept electrons and so undergo reduction

the standard cell potential difference

the measured cell potential difference, under standard difference, under standard conditions, when the concentration of each species in solution is 1 M, the pressure of a gas (where applicable) js 100kPa and the temperature is 25degrees

Standard hydrogen electrode

The Standard Hydrogen Electrode (SHE) is a redox electrode that serves as a reference point for measuring the electrode potentials of other half-cells. It is defined as having a potential of 0.00 volts under standard conditions (1 M H+, 1 atm H₂, 25°C). This allows scientists to compare the reactivity and electrochemical behavior of different substance