The concentration of dilute hydrochloric acid can be found by titration using a standard solution of sodium carbonate.
Calculate the mass, in g, of solid sodium carbonate (Mr=106.0M_r = 106.0Mr=106.0) needed to prepare 250 cm3250\text{ cm}^3250 cm3 of 0.0800 mol dm−30.0800\text{ mol dm}^{-3}0.0800 mol dm−3 sodium carbonate solution.
The mass of sodium carbonate from Part 1 is dissolved in a beaker containing 120 cm3120\text{ cm}^3120 cm3 of distilled water. Describe how this solution is used to make 250 cm3250\text{ cm}^3250 cm3 of the 0.0800 mol dm−30.0800\text{ mol dm}^{-3}0.0800 mol dm−3 sodium carbonate solution.
Before the first titration, the 25.0 cm325.0\text{ cm}^325.0 cm3 pipette is rinsed with a small volume of the 0.0800 mol dm−30.0800\text{ mol dm}^{-3}0.0800 mol dm−3 sodium carbonate solution. State why it is good practice to rinse the pipette in this way.
Hydrochloric acid is added to the burette using a funnel. State why it is good practice to remove the funnel from the burette before the titration.
In a different experiment, 1.18 g1.18\text{ g}1.18 g of solid sodium carbonate is used to make 250 cm3250\text{ cm}^3250 cm3 of standard sodium carbonate solution. 25.0 cm325.0\text{ cm}^325.0 cm3 of this sodium carbonate solution reacts with exactly 23.40 cm323.40\text{ cm}^323.40 cm3 of hydrochloric acid. The equation for the reaction is:
Na2CO3(aq)+2HCl(aq)→2NaCl(aq)+H2O(l)+CO2(g) \text{Na}_2\text{CO}_3(\text{aq}) + 2\text{HCl}(\text{aq}) \rightarrow 2\text{NaCl}(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g}) Na2CO3(aq)+2HCl(aq)→2NaCl(aq)+H2O(l)+CO2(g)Calculate the concentration of the hydrochloric acid. Give your answer to 3 significant figures.
The uncertainty in the 25.0 cm325.0\text{ cm}^325.0 cm3 of solution from the pipette is ±0.06 cm3\pm0.06\text{ cm}^3±0.06 cm3. The total uncertainty in the 23.40 cm323.40\text{ cm}^323.40 cm3 of solution from the burette is ±0.12 cm3\pm0.12\text{ cm}^3±0.12 cm3. Calculate the total percentage error in using the pipette and burette. Give your answer to 2 significant figures.
79 exam-style questions on AQA A Level Chemistry Amount of substance, covering Relative atomic mass and relative molecular mass, The mole and the Avogadro constant, The ideal gas equation, Empirical and molecular formula, and Balanced equations and associated calculations. Each one has a worked solution and a mark scheme showing where the marks go.