Products of electrolysis
When ions reach an electrodeA conductor used to establish electrical contact with a circuit. The electrode attached to the negative terminal of a battery is called a negative electrode, or cathode. The electrode attached to the positive terminal of a battery is the positive electrode, or anode., they gain or lose electrons. As a result, they form atoms or molecules of elements:
- positive ions gain electrons from the negatively charged cathode Negatively charged electrode.
- negative ions lose electrons at the positively charged anode Positively charged electrode.
Example
Predict the products of electrolysis of molten calcium chloride.
Positively charged calcium ions move to the negative electrode. Here, they gain electrons to form calcium atoms, so calcium is formed at the negative electrode.
Negatively charged chloride ions move to the positive electrode. Here, they lose electrons to form chlorine atoms. The atoms join up in pairs to form Cl2 molecules, so chlorine gas is formed at the positive electrode.
Question
Predict the products of electrolysis of molten aluminium oxide.
Aluminium will form at the negative electrode and oxygen will form at the positive electrode.