Chemistry 0620 · IGCSE · Electrolysis

Electrolysis — practice question

Sodium chloride is a standard example of an ionic compound.
(a(i))[2]

Complete the diagram so that it shows the ions present. Use '+' for Na$^+$ ions and '-' for Cl$^-$ ions. One ion has already been drawn for you.

(a(ii))[1]

How many electrons are present in a chloride ion?

(a(iii))[1]

Identify an element whose atoms have the same number of electrons as a sodium ion.

(b(i))[2]

What is meant by electrolysis?

(b(ii))[3]

Name the products formed by the electrolysis of concentrated aqueous sodium chloride.

(b(iii))[2]

Write the ionic half-equation for the reaction at the cathode. Include state symbols.

(c(i))[1]

Describe the observation made by the student in step 1.

(c(ii))[1]

Why did the student wash the residue in step 2?

(c(iii))[2]

Give the names of the two processes that took place in step 3.

(c(iv))[4]

Determine the amount of NaCl(aq) used. Calculate the mass of NaNO$_3$ crystals obtained.

(c(v))[2]

Write a chemical equation showing the effect of heat on sodium nitrate crystals.

Worked solution & mark scheme

This 21-mark question has a full step-by-step worked solution and mark scheme. One marking point: correct arrangement of ‘+’ and ‘-’ on the front four ions

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