Chemistry 0620 · IGCSE · Redox

Redox — practice question

Sulfuric acid is manufactured industrially by means of a four-stage sequence. step 1 Sulfur is burned in air, forming sulfur dioxide. step 2 Sulfur dioxide is changed into sulfur trioxide. step 3 Sulfur trioxide is combined with concentrated sulfuric acid to form oleum. step 4 Oleum is combined with water to form concentrated sulfuric acid.
(a(i))[1]

Some sulfur is obtained by mining. Name one additional major source of sulfur.

(a(ii))[1]

What is the name of the industrial process used to make sulfuric acid?

(a(iii))[5]

Describe the conversion of sulfur dioxide to sulfur trioxide in step 2. In your answer, include: • a chemical equation for the reaction • the essential reaction conditions.

(b(i))[1]

What substance is taken from the glucose in this reaction?

(b(ii))[1]

Name the black solid that is formed in this reaction.

(c(i))[1]

Define oxidation in terms of electron transfer.

(c(ii))[2]

Complete the dot-and-cross diagram so that it shows the electron arrangement in a molecule of hydrogen sulfide. Show only outer-shell electrons.

(c(iii))[2]

Hydrogen sulfide has a simple molecular structure. Explain why hydrogen sulfide has such a low boiling point.

(d(i))[1]

Calculate the number of moles of dilute sulfuric acid used in the titration.

(d(ii))[1]

Calculate the number of moles of sodium hydrogencarbonate required to neutralise the dilute sulfuric acid.

(d(iii))[1]

Calculate the volume, in cm$^3$, of $0.200\ \text{mol dm}^{-3}$ aqueous sodium hydrogencarbonate that is needed to neutralise the dilute sulfuric acid.

Worked solution & mark scheme

This 17-mark question has a full step-by-step worked solution and mark scheme. One marking point: petroleum/crude oil, or more generally fossil fuels

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