Chemistry 0620 · IGCSE · Diffusion

Diffusion — practice question

Concentrated ammonia solution releases ammonia gas, while concentrated hydrochloric acid releases hydrogen chloride gas. Ammonia, NH$_3$, and hydrogen chloride, HCl, are both colourless gases. When ammonia reacts with hydrogen chloride, the white solid ammonium chloride is produced. The apparatus is arranged as shown, with cotton wool soaked in concentrated hydrochloric acid at one end of a glass tube and cotton wool soaked in concentrated ammonia solution at the other end. Points A, B, C and D are marked along the tube. After ten minutes, a white solid appears in the tube where the two gases meet.
(a(i))[1]

Write the chemical equation for ammonia reacting with hydrogen chloride.

(a(ii))[1]

Name the process that makes the ammonia and hydrogen chloride gases travel along the tube.

(a(iii))[3]

At which point, A, B, C or D, does the white solid appear? Explain why it appears there.

(a(iv))[3]

The experiment was carried out again at a higher temperature. Predict how the outcome would change. Explain your answer.

(b(i))[3]

Describe how the white solid could be tested to show that it contains ammonium ions.

(b(ii))[3]

Describe how the white solid could be tested to show that it contains chloride ions.

(c(i))[1]

State the type of bonding present in ammonia.

(c(ii))[3]

Complete the diagram to show the electron arrangement in a molecule of hydrazine, using only outer-shell electrons.

(d(i))[1]

Name the linkages found in nylon and protein polymers.

(d(ii))[1]

Describe one structural difference between nylon and protein.

(d(iii))[1]

What is the general name for the products formed when proteins are hydrolysed?

(e)[1]

Suggest the structure of the monomer used to make the polymer shown.

Worked solution & mark scheme

This 22-mark question has a full step-by-step worked solution and mark scheme. One marking point: NH₃ + HCl → NH₄Cl

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