Problem 132
The \(\mathrm{pH}\) of a \(0.0642-M\) solution of a monoprotic acid is 3.86. Is this a strong acid?
Problem 133
Like water, liquid ammonia undergoes autoionization: $$ \mathrm{NH}_{3}+\mathrm{NH}_{3} \rightleftharpoons \mathrm{NH}_{4}^{+}+\mathrm{NH}_{2}^{-} $$ (a) Identify the Brönsted acids and Bronsted bases in this reaction. (b) What species correspond to \(\mathrm{H}_{3} \mathrm{O}^{+}\) and \(\mathrm{OH}^{-},\) and what is the condition for a neutral solution?
Problem 134
\(\mathrm{HA}\) and \(\mathrm{HB}\) are both weak acids although \(\mathrm{HB}\) is the stronger of the two. Will it take a larger volume of a \(0.10 \mathrm{M}\) \(\mathrm{NaOH}\) solution to neutralize \(50.0 \mathrm{~mL}\) of \(0.10 \mathrm{M} \mathrm{HB}\) than would be needed to neutralize \(50.0 \mathrm{~mL}\) of \(0.10 \mathrm{M}\) HA?
Problem 136
The three common chromium oxides are \(\mathrm{CrO}, \mathrm{Cr}_{2} \mathrm{O}_{3},\) and \(\mathrm{CrO}_{3}\). If \(\mathrm{Cr}_{2} \mathrm{O}_{3}\) is amphoteric, what can you say about the acid-base properties of \(\mathrm{CrO}\) and \(\mathrm{CrO}_{3} ?\)
Problem 139
Most of the hydrides of Group \(1 \mathrm{~A}\) and Group \(2 \mathrm{~A}\) metals are ionic (the exceptions are \(\mathrm{BeH}_{2}\) and \(\mathrm{MgH}_{2}\), which are covalent compounds). (a) Describe the reaction between the hydride ion \(\left(\mathrm{H}^{-}\right)\) and water in terms of a Brønsted acid-base reaction. (b) The same reaction can also be classified as a redox reaction. Identify the oxidizing and reducing agents.
Problem 140
A \(10.0-\mathrm{g}\) sample of white phosphorus was burned in an excess of oxygen. The product was dissolved in enough water to make \(500.0 \mathrm{~mL}\) of solution. Calculate the \(\mathrm{pH}\) of the solution at \(25^{\circ} \mathrm{C}\).
Problem 142
Which of the following is the stronger base: \(\mathrm{NF}_{3}\) or \(\mathrm{NH}_{3}\) ? (Hint: \(\mathrm{F}\) is more electronegative than \(\mathrm{H}\).)
Problem 143
Which of the following is a stronger base: \(\mathrm{NH}_{3}\) or \(\mathrm{PH}_{3}\) ? (Hint: The \(\mathrm{N}-\mathrm{H}\) bond is stronger than the \(\mathrm{P}-\mathrm{H}\) bond. \()\)
Problem 144
The ion product of \(\mathrm{D}_{2} \mathrm{O}\) is \(1.35 \times 10^{-15}\) at \(25^{\circ} \mathrm{C}\). (b) For (a) Calculate \(\mathrm{pD}\) where \(\mathrm{pD}=-\log \left[\mathrm{D}_{3} \mathrm{O}^{+}\right]\). what values of \(\mathrm{pD}\) will a solution be acidic in \(\mathrm{D}_{2} \mathrm{O} ?\) (c) Derive a relation between \(\mathrm{pD}\) and \(\mathrm{pOD}\).
Problem 145
Give an example of (a) a weak acid that contains oxygen atoms, (b) a weak acid that does not contain oxygen atoms, (c) a neutral molecule that acts as a Lewis acid, (d) a neutral molecule that acts as a Lewis base, (e) a weak acid that contains two ionizable \(\mathrm{H}\) atoms, (f) a conjugate acid-base pair, both of which react with \(\mathrm{HCl}\) to give carbon dioxide gas.
