Electrolysis Concepts

Why is the positive anode graphite block replaced regularly during the electrolysis of aluminium oxide?

• The oxygen formed reacts with the carbon anode to produce carbon dioxide.

• The anode becomes too hot and melts during the process.

• The anode loses its electrical conductivity over time.

• The anode is consumed in the reaction and needs to be replenished.

What is the rule for predicting the product formed at the cathode if a solution is electrolysed?

• If the metal is more reactive than hydrogen, then hydrogen is formed; if not, then the metal is formed.

• The product formed is always hydrogen, regardless of the metal's reactivity.

• The product formed is the metal, regardless of its reactivity compared to hydrogen.

• The product formed depends on the temperature of the solution.

Name the products formed at each electrode during the electrolysis of aqueous sodium iodide?

• Anode - Iodine, Cathode - Hydrogen

• Anode - Chlorine, Cathode - Sodium

• Anode - Oxygen, Cathode - Hydrogen

• Anode - Iodine, Cathode - Oxygen

What is reduction in terms of electrons?

• A loss of electrons

• A gain of protons

• A gain of electrons

• An increase in energy

What is the rule for predicting the product formed at the anode if a solution is electrolysed?

• If the non-metal is a halogen (Group 7) then the halogen is formed, if not then oxygen is formed.

• Only metals are formed at the anode during electrolysis.

• Hydrogen is always produced at the anode regardless of the solution.

• The product at the anode depends solely on the temperature of the solution.

The positive electrode attracts which ion?

• Positive ions which gain electrons

• Neutral ions with no charge

• Negative ions which lose electrons

• Positive ions which lose electrons

Which type of substances can only be electrolysed?

• Ionic

• Covalent

• Metallic

• Molecular

What are the 2 ions that come from water?

• H+ and OH- ions.

• Na+ and Cl- ions.

• Ca2+ and Mg2+ ions.

• K+ and SO4^2- ions.

Name the products formed during the electrolysis of aqueous calcium nitrate

• Hydrogen and oxygen.

• Calcium and nitrogen.

• Nitrogen and oxygen.

• Hydrogen and calcium.

Why does electrolysis only works if the electrolyte is either molten or in solution?

• The ions need to be free to move.

• The electrolyte must be a solid.

• Electrolysis requires a gas to function.

• The temperature must be below freezing.