Problem 108
A fertilizer railroad car carrying \(129,840 \mathrm{~L}\) of commercial aqueousammonia (30\% ammonia by mass) tips over and spills. The density of the aqueous ammonia solution is \(0.88 \mathrm{~g} / \mathrm{cm}^{3}\). What mass of citric acid, \(\mathrm{C}(\mathrm{OH})(\mathrm{COOH})\left(\mathrm{CH}_{2} \mathrm{COOH}\right)_{2},\) (which contains three acidic protons) is required to neutralize the spill?
Problem 109
A sample of \(8.69 \mathrm{~g}\) of \(\mathrm{Zn}(\mathrm{OH})_{2}\) is added to \(155.0 \mathrm{~mL}\) of \(0.750 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}\). (a) Write the chemical equation for the reaction that occurs. (b) Which is the limiting reactant in the reaction? (c) How many moles of \(\mathrm{Zn}(\mathrm{OH})_{2}, \mathrm{H}_{2} \mathrm{SO}_{4},\) and \(\mathrm{ZnSO}_{4}\) are present after the reaction is complete?
Problem 110
In 2014 , a major chemical leak at a facility in West Virginia released \(28,390 \mathrm{~L}\) of MCHM (4-methylcyclohexylmethanol, \(\mathrm{C}_{8} \mathrm{H}_{16} \mathrm{O}\) ) into the Elk River. The density of MCHM is 0.9074 \(\mathrm{g} / \mathrm{mL}\). (a) Calculate the initial molarity of MCHM in the river, assuming that the first part of the river is \(2.00 \mathrm{~m}\) deep, \(90.0 \mathrm{~m}\) wide, and \(90.0 \mathrm{~m}\) long. (b) How much farther down the river would the spill have to spread in order to achieve a "safe" MCHM concentration of \(1.00 \times 10^{-4} \mathrm{M}\) ? Assume the depth and width of the river are constant and the concentration of MCHM is uniform along the length of the spill.
Problem 112
A \(3.50 \mathrm{~g}\) of an alloy which contains only lead and tin is dissolved in hot \(\mathrm{HNO}_{3} .\) Excess sulfuric acid is added to this solution and \(1.57 g\) of \(\mathrm{PbSO}_{4}(s)\) is obtained. (a) Write the net ionic equation for the formation of \(\mathrm{PbSO}_{4}\). (b) Assuming all the lead in the alloy reacted to form \(\mathrm{PbSO}_{4}\), what was the amount, in grams, of lead and tin in the alloy respectively?
Problem 113
The arsenic in a \(1.22-\mathrm{g}\) sample of a pesticide was converted to \(\mathrm{AsO}_{4}{ }^{3-}\) by suitable chemical treatment. It was then titrated using \(\mathrm{Ag}^{+}\) to form \(\mathrm{Ag}_{3} \mathrm{AsO}_{4}\) as a precipitate. (a) What is the oxidation state of \(\mathrm{As}\) in \(\mathrm{AsO}_{4}^{3-} ?(\mathbf{b})\) Name \(\mathrm{Ag}_{3} \mathrm{AsO}_{4}\) by analogy to the corresponding compound containing phosphorus in place of arsenic. (c) If it took \(25.0 \mathrm{~mL}\) of \(0.102 \mathrm{MAg}^{+}\) to reach the equivalence point in this titration, what is the mass percentage of arsenic in the pesticide?
Problem 114
The U.S. standard for arsenate in drinking water requires that public water supplies must contain no greater than 10 parts per billion (ppb) arsenic. If this arsenic is present as arsenate, \(\mathrm{AsO}_{4}^{3-},\) what mass of sodium arsenate would be present in a \(1.00-\mathrm{L}\) sample of drinking water that just meets the standard? Parts per billion is defined on a mass basis as $$ \mathrm{ppb}=\frac{\mathrm{g} \text { solute }}{\mathrm{g} \text { solution }} \times 10^{9} $$
Problem 115
Federal regulations set an upper limit of 50 parts per million (ppm) of \(\mathrm{NH}_{3}\) in the air in a work environment [that is, 50 molecules of \(\mathrm{NH}_{3}(g)\) for every million molecules in the air]. Air from a manufacturing operation was drawn through a solution containing \(1.00 \times 10^{2} \mathrm{~mL}\) of \(0.0105 \mathrm{M} \mathrm{HCl}\). The \(\mathrm{NH}_{3}\) reacts with HCl according to: $$ \mathrm{NH}_{3}(a q)+\mathrm{HCl}(a q) \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}(a q) $$ After drawing air through the acid solution for 10.0 min at a rate of \(10.0 \mathrm{~L} / \mathrm{min},\) the acid was titrated. The remaining acid needed \(13.1 \mathrm{~mL}\) of \(0.0588 \mathrm{M} \mathrm{NaOH}\) to reach the equivalence point. (a) How many grams of \(\mathrm{NH}_{3}\) were drawn into the acid solution? (b) How many ppm of \(\mathrm{NH}_{3}\) were in the air? (Air has a density of \(1.20 \mathrm{~g} / \mathrm{L}\) and an average molar mass of \(29.0 \mathrm{~g} / \mathrm{mol}\) under the conditions of the experiment.) \((\mathbf{c})\) Is this manufacturer in compliance with regulations?
