A student investigates the reaction between calcium carbonate and hydrochloric acid:
CaCO3(s)+2HCl(aq)→CaCl2(aq)+H2O(l)+CO2(g) \text{CaCO}_3(\text{s}) + 2\text{HCl}(\text{aq}) \rightarrow \text{CaCl}_2(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g}) CaCO3(s)+2HCl(aq)→CaCl2(aq)+H2O(l)+CO2(g)The student adds an excess of calcium carbonate to 30.00 cm330.00\text{ cm}^330.00 cm3 of HCl(aq)\text{HCl}(\text{aq})HCl(aq) in a conical flask, which is quickly connected to a gas syringe.
The reaction is allowed to proceed until no more gas is evolved. The final volume of CO2\text{CO}_2CO2 collected in the syringe is 85 cm385\text{ cm}^385 cm3, measured at room temperature and pressure (RTP).
Calculate the initial concentration of the HCl(aq)\text{HCl}(\text{aq})HCl(aq) solution. Give your answer to two significant figures. (Assume the molar gas volume at RTP is 24.0 dm3 mol−124.0\text{ dm}^3\text{ mol}^{-1}24.0 dm3 mol−1.)
199 exam-style questions on OCR A A Level Chemistry Atoms and reactions, covering Atomic structure and isotopes, Compounds, formulae and equations, Amount of substance, Acids, and Redox. Each one has a worked solution and a mark scheme showing where the marks go.