An environmental chemist is investigating the neutralisation of acidic run-off from an industrial site. The run-off contains hydrochloric acid, HCl\text{HCl}HCl.
The chemist uses solid sodium carbonate, Na2CO3\text{Na}_2\text{CO}_3Na2CO3, to neutralise the acid according to the equation:
Na2CO3(s)+2HCl(aq)→2NaCl(aq)+H2O(l)+CO2(g) \text{Na}_2\text{CO}_3(\text{s}) + 2\text{HCl}(\text{aq}) \rightarrow 2\text{NaCl}(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g}) Na2CO3(s)+2HCl(aq)→2NaCl(aq)+H2O(l)+CO2(g)In a laboratory simulation, the chemist tests a 250 cm3250\text{ cm}^3250 cm3 sample of the run-off which has a hydrochloric acid concentration of 0.160 mol/dm30.160\text{ mol/dm}^30.160 mol/dm3.
They add 2.65 g2.65\text{ g}2.65 g of solid sodium carbonate to the sample.
Calculate the amount, in moles, of HCl\text{HCl}HCl in the run-off sample.
Calculate the amount, in moles, of Na2CO3\text{Na}_2\text{CO}_3Na2CO3 added to the sample. [Mr of Na2CO3=106M_{\text{r}}\text{ of }\text{Na}_2\text{CO}_3 = 106Mr of Na2CO3=106]
Explain whether the chemist added the correct amount of sodium carbonate to exactly neutralise the hydrochloric acid.
80 exam-style questions on Edexcel IGCSE Chemistry Chemical formulae, equations and calculations. Each one has a worked solution and a mark scheme showing where the marks go.