Problem 80
If you have a sample of water in a closed container, some of the water will evaporate until the pressure of the water vapor, at \(25^{\circ} \mathrm{C},\) is \(23.8 \mathrm{mm}\) Hg. How many molecules of water per cubic centimeter exist in the vapor phase?
Problem 81
You are given \(1.56 \mathrm{g}\) of a mixture of \(\mathrm{KClO}_{3}\) and \(\mathrm{KCl}\). When heated, the KClOs decomposes to KCl and \(\mathrm{O}_{2}\), $$ 2 \mathrm{KClO}_{3}(\mathrm{s}) \longrightarrow 2 \mathrm{KCl}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{g}) $$ and \(327 \mathrm{mL}\) of \(\mathrm{O}_{2}\) with a pressure of \(735 \mathrm{mm} \mathrm{Hg}\) is collected at \(19^{\circ} \mathrm{C}\). What is the weight percentage of \(\mathrm{KClO}_{3}\) in the sample?
Problem 82
A A study of climbers who reached the summit of Mount Everest without supplemental oxygen showed that the partial pressures of \(\mathrm{O}_{2}\) and \(\mathrm{CO}_{2}\) in their lungs were \(35 \mathrm{mm}\) Hg and \(7.5 \mathrm{mm}\) Hg, respectively. The barometric pressure at the summit was \(253 \mathrm{mm}\) Hg. Assume the lung gases are saturated with moisture at a body temperature of \(37^{\circ} \mathrm{C}\) [which means the partial pressure of water vapor in the lungs is \(P\left(\mathrm{H}_{2} \mathrm{O}\right)=47.1 \mathrm{mm} \mathrm{Hg}\) ]. If you assume the lung gases consists of only \(\mathrm{O}_{2}, \mathrm{N}_{2}, \mathrm{CO}_{2},\) and \(\mathrm{H}_{2} \mathrm{O},\) what is the partial pressure of \(\mathrm{N}_{2} ?\)
Problem 83
Nitrogen monoxide reacts with oxygen to give nitrogen dioxide: $$ 2 \mathrm{NO}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{NO}_{2}(\mathrm{g}) $$ (a) Place the three gases in order of increasing rms speed at \(298 \mathrm{K}\) (b) If you mix \(\mathrm{NO}\) and \(\mathrm{O}_{2}\) in the correct stoichiometric ratio, and NO has a partial pressure of \(150 \mathrm{mm} \mathrm{Hg}\) what is the partial pressure of \(\mathrm{O}_{2} ?\) (c) After reaction between \(\mathrm{NO}\) and \(\mathrm{O}_{2}\) is complete, what is the pressure of \(\mathrm{NO}_{2}\) if the NO originally had a pres. sure of \(150 \mathrm{mm} \mathrm{Hg}\) and \(\mathrm{O}_{2}\) was added in the correct stoichiometric amount?
Problem 84
Ammonia gas is synthesized by combining hydrogen and nitrogen: $$ 3 \mathrm{H}_{2}(\mathrm{g})+\mathrm{N}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{NH}_{3}(\mathrm{g}) $$ (a) If you want to produce 562 g of \(\mathrm{NH}_{3}\), what volume of \(\mathrm{H}_{2}\) gas, at \(56^{\circ} \mathrm{C}\) and \(745 \mathrm{mm} \mathrm{Hg}\), is required? (b) To produce 562 g of \(\mathrm{NH}_{3},\) what volume of air (the source of \(\mathrm{N}_{2}\) ) is required if the air is introduced at \(29^{\circ} \mathrm{C}\) and \(745 \mathrm{mm}\) Hg? (Assume the air sample has \(\left.78.1 \text { mole } \% N_{2} .\right)\)
Problem 85
You have a \(550-\mathrm{ml}\). tank of gas with a pressure of 1.56 atm at \(24^{\circ} \mathrm{C}\). You thought the gas was pure carbon monoxide gas, \(\mathrm{CO}\), but you later found it was contaminated by small quantities of gaseous \(\mathrm{CO}_{2}\) and \(\mathrm{O}_{2}\). Analysis shows that the tank pressure is 1.34 atm (at \(24^{-} \mathrm{C}\) ) if the \(\mathrm{CO}_{2}\) is removed. Another experiment shows that \(0.0870 \mathrm{~g}\) of \(\mathrm{O}_{2}\) can be removed chemically. What are the masses of \(\mathrm{CO}\) and \(\mathrm{CO}_{2}\) in the tank, and what is the partial pressure of each of the three gases at \(25^{\circ} \mathrm{C}\) ?
Problem 86
Methane is burned in a laboratory Bunsen burner to give \(\mathrm{CO}_{2}\) and water vapor. Methane gas is supplied to the burner at the rate of \(5.0 \mathrm{L} / \mathrm{min}\) (at a temperature of \(28^{\circ} \mathrm{C}\) and a pressure of \(773 \mathrm{mm} \mathrm{Hg}\) ). At what rate must oxygen be supplicd to the burner (at a pressure of \(742 \mathrm{mm} \mathrm{Hg}\) and a temperature of \(26^{\circ} \mathrm{C}\) ) \(?\)
Problem 88
Group 2 A metal carbonates are decomposed to the metal oxide and \(\mathrm{CO}_{2}\) on heating: $$ \mathrm{MCO}_{3}(\mathrm{s}) \longrightarrow \mathrm{MO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g}) $$ You heat \(0.158 \mathrm{g}\) of a white, solid carbonate of a Group \(2 \mathrm{A}\) metal (M) and find that the evolved \(\mathrm{CO}_{2}\) has a pressure of \(69.8 \mathrm{mm} \mathrm{Hg}\) in a \(285-\mathrm{mL}\). Hask at \(25^{\circ} \mathrm{C} .\) Identify \(\mathrm{M}\).
Problem 89
Silane, \(\mathrm{SiH}_{4},\) reacts with \(\mathrm{O}_{2}\) to give silicon dioxide and water vapor: $$ \mathrm{SiH}_{4}(\mathrm{g})+2 \mathrm{O}_{2}(\mathrm{g}) \longrightarrow \mathrm{SiO}_{2}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) $$ If you mix \(\mathrm{SiH}_{4}\) with \(\mathrm{O}_{2}\) in the correct stoichiometric ratio, and if the total pressure of the mixture is \(120 \mathrm{mm} \mathrm{Hg}\), what are the partial pressures of \(\mathrm{SiH}_{4}\) and \(\mathrm{O}_{2} ?\) When the reactants have been completely consumed, what is the total pressure in the flask? (Assume T is constant.)
Problem 91
One way to synthesize diborane, \(\mathrm{B}_{2} \mathrm{H}_{6}\), is the reaction \(2 \mathrm{NaBH}_{4}(\mathrm{s})+2 \mathrm{H}_{3} \mathrm{PO}_{4}(\mathrm{aq}) \longrightarrow\) $$ \mathrm{B}_{2} \mathrm{H}_{6}(\mathrm{g})+2 \mathrm{NaH}_{2} \mathrm{PO}_{4}(\mathrm{aq})+2 \mathrm{H}_{2}(\mathrm{g}) $$ (a) If you have \(0.136 \mathrm{g}\) of \(\mathrm{NaBH}_{4}\) and excess \(\mathrm{H}_{3} \mathrm{PO}_{4},\) and you collect the \(\mathrm{B}_{2} \mathrm{H}_{6}\) in a 2.75 L. flask at \(25^{\circ} \mathrm{C},\) what is the pressure of the \(\mathrm{B}_{2} \mathrm{H}_{6}\) in the flask? (b) A byproduct of the reaction is \(\mathrm{H}_{2}\) gas. If both \(\mathrm{B}_{2} \mathrm{H}_{6}\) and H \(_{2}\) gas come from this reaction, what is the total pressure in the 2.75 -L. flask (after reaction of \(0.136 \mathrm{g}\) of NaBH, with excess \(\mathrm{H}_{3} \mathrm{PO}_{4}\) ) at \(25^{\circ} \mathrm{C} ?^{2}\)
