Chapter 9

What mass of substance would be required to prepare each of the following (answer in each case to four decimal places): (a) \(250.00 \mathrm{~mL}\) of sodium chloride \((0.05 \mathrm{M})\) from \(\mathrm{NaCl} ?\) (b) \(100.00 \mathrm{~mL}\) of potassium iodate \((0.02 \mathrm{M}\) ) from \(\mathrm{KIO}_{3} ?\) (c) \(50.00 \mathrm{~mL}\) of sodium thiosulphate \((0.05 \mathrm{M})\) from \(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3} \cdot 5 \mathrm{H}_{2} \mathrm{O} ?\) (d) \(250.00 \mathrm{~mL}\) of copper ions \((0.1 \mathrm{M})\) from \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} ?\) (e) \(100.00 \mathrm{~mL}\) of potassium ions \((0.05 \mathrm{M})\) from \(\mathrm{K}_{2} \mathrm{SO}_{4} ?\)

Practise the calculations involved in dilutions (answer in each case to four decimal places). (a) If you added sodium chloride solution \((1.00 \mathrm{~mL} ; 0.4 \mathrm{M}\) ) to a volumetric flask \((10.00 \mathrm{~mL})\) and made up to the mark with water, what would be the concentration of the diluted solution? (b) Calculate the volume a solution of copper (II) sulphate \((0.1 \mathrm{M})\) required to produce \(500.00\) \(\mathrm{mL}\) of \(0.02 \mathrm{M}\) solution. (c) What would be the concentration of a solution of \(\mathrm{Fe}^{2+}\) ions if \(10.00 \mathrm{~mL}\) is diluted to \(250.00 \mathrm{~mL}\) to give a concentration of \(0.001 \mathrm{M} ?\) (d) You are provided with a solution of \(\mathrm{KMnO}_{4}(0.02 \mathrm{M})\); to what volume must \(5.00 \mathrm{~mL}\) of this solution be diluted to give a concentration of \(0.001 \mathrm{M}\) ?