Chemistry 0620 · IGCSE · Water

Water — practice question

Table 2.1 lists the masses of several ions present in a $1000\,\text{cm}^3$ sample of river water.
(a(i))[1]

Name the negative ion with the greatest concentration.

(a(ii))[1]

Name the compound formed from only $\text{NH}_4^+$ and $\text{SO}_4^{2-}$ ions.

(a(iii))[1]

Calculate the mass of hydrogencarbonate ions present in $200\,\text{cm}^3$ of river water.

(b)[2]

Give a test for sodium ions. State the test and the observations.

(c)[1]

Most nitrate ions in river water originate from fertilisers applied to fields. Describe the advantage of using fertilisers.

(d)[2]

Water from natural sources can become contaminated with harmful substances. State why sewage and phosphates in river water are harmful.

(e(i))[1]

Draw the displayed formula for ethanoic acid.

(e(ii))[2]

Ethanoic acid reacts with sodium hydroxide. Complete the word equation for this reaction. ethanoic acid + sodium hydroxide → [BLANK] + [BLANK]

(e(iii))[2]

Complete Table 2.2 so that the relative molecular mass of $\text{C}_5\text{H}_{10}\text{O}_2$ can be calculated.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: phosphate ion

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