Question

An experiment was carried out at 25 °C by dissolving an unknown mass of limestone granules into excess 1 mol dm–3 hydrochloric acid. The volume of gas produced over a period of 6 minutes was measured using a gas syringe. The result was plotted as shown in Figure 1.


to calculate the moles of gas produced at STP

[1 mole of any gas at STP has a volume of 22 400 cm3.]












(1 mark )

to calculate the mass of limestone granules used.

[Relative molecular mass of CaCO3 is 100.]

Answer 1

${m(CaCO3) \over M(CaCO3)}= {V(gas) \over 22400}$

$m(CaCO3) = {M(CaCO3)*V(gas) \over 22400}$

$m = {100*49 \over 22400}$

m = 0,22 g