This question is about pH calculations, buffers and the preparation of standard solutions.
What is the pH of 1.50 dm31.50\text{ dm}^31.50 dm3 of 0.125 mol dm−30.125\text{ mol dm}^{-3}0.125 mol dm−3 of LiOH(aq)\text{LiOH(aq)}LiOH(aq) at 298 K298\text{ K}298 K?
[Kw=1.00×10−14 mol2 dm−6K_w = 1.00 \times 10^{-14}\text{ mol}^2\text{ dm}^{-6}Kw=1.00×10−14 mol2 dm−6 at 298 K298\text{ K}298 K]
Water is added to 25.0 cm325.0\text{ cm}^325.0 cm3 of 0.600 mol dm−30.600\text{ mol dm}^{-3}0.600 mol dm−3 HCl(aq)\text{HCl(aq)}HCl(aq) to produce 400 cm3400\text{ cm}^3400 cm3 of diluted HCl(aq)\text{HCl(aq)}HCl(aq).
What is the pH of the diluted HCl(aq)\text{HCl(aq)}HCl(aq)? Give your answer to 2 decimal places.
A buffer solution has concentrations of 0.350 mol dm−30.350\text{ mol dm}^{-3}0.350 mol dm−3 HCOOH(aq)\text{HCOOH(aq)}HCOOH(aq) and 0.220 mol dm−30.220\text{ mol dm}^{-3}0.220 mol dm−3 HCOONa(aq)\text{HCOONa(aq)}HCOONa(aq).
KaK_aKa for HCOOH=1.78×10−4 mol dm−3\text{HCOOH} = 1.78 \times 10^{-4}\text{ mol dm}^{-3}HCOOH=1.78×10−4 mol dm−3 at 298 K298\text{ K}298 K.
What is the pH of the solution at 298 K298\text{ K}298 K? Give your answer to 2 decimal places.
A student is provided with hydrated copper(II) sulfate, CuSO4⋅5H2O\text{CuSO}_4 \cdot 5\text{H}_2\text{O}CuSO4⋅5H2O.
The student needs to prepare a standard solution of CuSO4⋅5H2O\text{CuSO}_4 \cdot 5\text{H}_2\text{O}CuSO4⋅5H2O with a concentration of 0.120 mol dm−30.120\text{ mol dm}^{-3}0.120 mol dm−3. Describe how the student would prepare 250.0 cm3250.0\text{ cm}^3250.0 cm3 of this solution, giving quantities, apparatus and method.
[Use molar masses: Cu=63.5 g mol−1\text{Cu} = 63.5\text{ g mol}^{-1}Cu=63.5 g mol−1, S=32.1 g mol−1\text{S} = 32.1\text{ g mol}^{-1}S=32.1 g mol−1, O=16.0 g mol−1\text{O} = 16.0\text{ g mol}^{-1}O=16.0 g mol−1, H=1.0 g mol−1\text{H} = 1.0\text{ g mol}^{-1}H=1.0 g mol−1]
