Electrolysis of solutions exam Qs

The imagine shows the electrolysis of molten magnesium chloride, which contains magnesium and chloride ions.

Why do magnesium ions (Mg²⁺) move to the negative electrode?

• They need to gain electrons

• Opposite charges attract

• They move around randomly, so some hit the electrode

• They need to lose electrons

The imagine shows the electrolysis of molten magnesium chloride, which contains magnesium and chloride ions.

Why does solid magnesium chloride not conduct electricity?

• It does not contain any ions

• There is no space between the ions

• The ions are fixed in position

• Ions in a solid do not have strong attractions

At the negative electrode, the magnesium ions (Mg²⁺) gain electrons to become magnesium atoms.

How many electrons does each magnesium ion gain?

What is the name given to solutions that conduct electricity?

• electrodes

• acids

• electrolytes

• electrosolutes

In the electrolysis of molten lead bromide, the electrolyte contains lead (Pb²⁺) and bromide (Br^-) ions. At the positive electrode, the gas produced is...

• lead

• bromide

• bromine

• oxygen

In the electrolysis of molten lead bromide, the electrolyte contains lead (Pb²⁺) and bromide (Br^-) ions.

At the negative electrode, lead ............ gain electrons to become lead .............

• ions, atoms

• atoms, ions

• ions, bromide

• atoms, molecules

Use the table to help you name the products formed at each electrode if you electrolysed an aqueous solution of potassium bromide.

What would be produced at the cathode?

• potassium

• hydrogen

• bromine

• chlorine

Use the table to help you name the products formed at each electrode if you electrolysed an aqueous solution of potassium bromide.

What would be produced at the anode?

• potassium

• hydrogen

• bromine

• chlorine

Electrolysis is used to extract magnesium metal from magnesium chloride.

The equation shows the reaction that takes place at the positive electrode. 

2Cl^– - 2e^– → Cl₂

Why is this an oxidation reaction?

• Because chlorine gains electrons

• Because the charges add up

• Because the chloride ions lose electrons

• Because the chloride ions become atoms

Electrolysis is used to extract magnesium metal from magnesium chloride.

Complete the equation for the reaction at the negative electrode.

 

Mg²⁺     +   …….. → Mg

• 2e^-

• (aq)

• e^-

• Mg^2-