Chapter 7

What physical propertics are used for the separation of the components of a mixture by (a) filrration; (b) chromatography; (c) distillation?

Identify the following as homogencous or hcterogeneous mixtures and suggest a technique for scparating their components: (a) gasolinc and motor oil; (b) carbonated water; (c) charcoal and sugar.

A chemist studying the propertics of photographic emulsions needed to prepare \(25.00 \mathrm{~mL}\). of \(0.155 \mathrm{M}\) \(\mathrm{AgNO}_{3}\) (aq). What mass of silver nitrate must be placed into a \(25.00-\mathrm{mL}\) volumctric flask and dissolved and diluted to the mark with water?

(a) A chemist prepared a solution by dissolving \(1.230 \mathrm{~g}\) of \(\mathrm{KCl}\) in enough water to make \(150.0 \mathrm{~mL}\) of solution. What molar concentration of potassium chloride should appear on the label? (b) If the chemist had mistakenly used a 500 -mL. volumetric flask instead of the 150.0-mL flask in (a), what molar concentration of potassium chloride has the chemist actually prepared?

A student investigating the propertics of solutions containing carbonate ions prepared a solution containing \(7.112 \mathrm{~g}\) of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) in a \(250.0-\mathrm{mL}\) volumetric flask. Some of the solution was transferred to a burer. What volume of solution should be dispensed from the buret to provide (a) \(5.112 \times 10^{-3} \mathrm{~mol} \mathrm{Na}_{2} \mathrm{CO}_{3}\); (b) \(3.451 \times 10^{-3} \mathrm{~mol} \mathrm{CO}_{3}^{2-}\) ?

Explain how you would prepare an aqueous solution of \(0.010 \mathrm{M} \mathrm{KMnO}_{4}(\mathrm{aq})\) starting with (a) solid \(\mathrm{KMnO}_{4} ;\) (b) \(0.050 \mathrm{M} \mathrm{KMnO}_{4}\) (aq).

(a) A 12.56-mL sample of \(1.345 \mathrm{M} \mathrm{K}_{2} \mathrm{SO}_{4}(\mathrm{aq})\) is diluted to \(250.0 \mathrm{~mL}\). What is the molar concentration of \(\mathrm{K}_{2} \mathrm{SO}_{4}\) in the diluted solution? (b) A \(25.00-\mathrm{mL}\) sample of \(0.366 \mathrm{M} \mathrm{HCl}(\mathrm{aq})\) is drawn from a reagent bottle with a pipet. The sample is transferred to a \(125.00-\mathrm{mL}\) volumetric flask and diluted to the mark with water. What is the molar concentration of the dilute hydrochloric acid solution?

(a) What volume of a \(0.778 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}\) (aq) solution should be diluted to \(150.0 \mathrm{~mL}\) with water to reduce its concentration to \(0.0234 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})\) ? (b) An experiment requires the use of \(60.0 \mathrm{~mL}\) of \(0.50 \mathrm{M} \mathrm{NaOH}\) (aq). The stockroom assistant can only find a reagent bottle of \(2.5 \mathrm{M} \mathrm{NaOH}\) (aq). How is the \(0.50 \mathrm{M} \mathrm{NaOH}(\) aq \()\) solution to be prepared?

(a) Determine the mass of anhydrous copper(II) sulfate that must be used to prepare \(250 \mathrm{~mL}\) of a \(0.20 \mathrm{M} \mathrm{CuSO}_{4}(\mathrm{aq})\) solution. (b) Determine the mass of \(\mathrm{CuSO}_{4}-5 \mathrm{H}_{2} \mathrm{O}\) that must be used to prepare \(250 \mathrm{ml}\). of a \(0.20 \mathrm{M} \mathrm{CuSO}_{4}(\mathrm{aq})\) solution.

The sulfuric acid solution that is purchased for a stockroom has a molarity of \(17.8\) M; all sulfuric acid solutions for experiments are prepared by dilution of this stock solution. (a) Determine the volume of \(17.8 \mathrm{M}\) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) that must be diluted to \(250 \mathrm{~mL}\) to prepare a \(2.0 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq})\) solution. (b) An experiment requires a \(0.50 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq})\) solution. The stockroom manager estimates that \(6.0\) L of the acid is needed. What volume of \(17.8 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq})\) must be used for the preparation?