91Ó°ÊÓ

Which one of the following steps in the dissolving process must have a negative value for \(\Delta E\) ? Explain your answer. (a) The physical separation of solute particles (b) The formation of solvent-solute interactions (c) The physical separation of solvent particles (d) None of the above

How many moles of potassium permanganate, \(\mathrm{KMnO}_{4}\), are there in \(28.86 \mathrm{~mL}\) of a \(5.20 \times 10^{-3} \mathrm{M}\) solution of \(\mathrm{KMnO}_{4} ?\)

Combustion analysis reveals vitamin \(\mathrm{C}\) to be \(40.9 \%\) by mass \(\mathrm{C}\) and \(4.58 \%\) by mass \(\mathrm{H}\). The only other element present is oxygen. A solution of \(19.40 \mathrm{~g}\) of vitamin \(\mathrm{C}\) in \(100.0 \mathrm{~g}\) of water freezes at \(22.05^{\circ} \mathrm{C}\). What is the molecular formula of vitamin \(C\) ?

Suppose \(250.0 \mathrm{~mL}\) of a \(0.600 \mathrm{M}\) solution of barium nitrate is combined with enough \(0.500 \mathrm{M}\) sodium sulfate solution to precipitate the maximum amount of barium sulfate. What volume of the sodium sulfate solution is required?

What volume of a \(0.245 \mathrm{M}\) solution of \(\mathrm{NaI}\) would you need to add to \(100.0 \mathrm{~mL}\) of a \(0.300 \mathrm{M}\) solution of lead acetate to precipitate out all the lead? Which ions are spectators?

Citric acid can produce \(3 \mathrm{H}^{+}(a q)\) ions per molecule. A solution of citric acid is prepared by dissolving \(0.177 \mathrm{~g}\) of solid citric acid in enough water to yield \(100.0 \mathrm{~mL}\) of solution. When this solution is titrated with \(0.1001 \mathrm{M} \mathrm{NaOH}(a q)\), the indicator turns color after \(27.55 \mathrm{~mL}\) of \(\mathrm{NaOH}(a q)\) has been added. (a) What is the molar concentration of citric acid? (b) What is the molar mass of citric acid?

A 25.00-mL sample of a hydrochloric acid solution of unknown concentration is titrated with \(0.1004 \mathrm{M}\) \(\mathrm{NaOH}\). However, before the acid is titrated, \(27.65\) mL of water is added to it. The phenolphthalein indicator turns red after \(28.70 \mathrm{~mL}\) of \(\mathrm{NaOH}\) has been added. What is the concentration of the \(25.00-\) \(\mathrm{mL}\) sample of hydrochloric acid?

Identify the solvent and the solute in each solution: (a) Brass, which is 60 to \(80 \% \mathrm{Cu}\), and 18 to \(40 \% Z n\) (b) Household ammonia cleaner, which is \(1 \%\) by mass ammonia gas in water (c) \(2.59 \mathrm{~g}\) of sucrose in \(1.00 \mathrm{~g}\) of water at \(50^{\circ} \mathrm{C}\)

Describe at the molecular level what is happening when solid iodine, \(\mathrm{I}_{2}(s)\), dissolves in carbon tetrachloride liquid, \(\operatorname{CCl}_{4}(l)\).

What is the difference between hydration and solvation? Does one process always release more energy than the other? Explain.