Problem 96
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 supplied to the burner (at a pressure of \(742 \mathrm{mm} \mathrm{Hg}\) and a temperature of \(\left.26^{\circ} \mathrm{C}\right) ?\)
Problem 97
Iron forms a series of compounds of the type \(\mathrm{Fe}_{x}(\mathrm{CO})_{y}\). In air, these compounds are oxidized to \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) and \(\mathrm{CO}_{2}\) gas. After heating a 0.142-g sample of \(\mathrm{Fe}_{x}(\mathrm{CO})_{y}\) in air, you isolate the \(\mathrm{CO}_{2}\) in a \(1.50-\mathrm{L}\) flask at \(25^{\circ} \mathrm{C}\). The pressure of the gas is \(44.9 \mathrm{mm}\) Hg. What is the empirical formula of \(\mathrm{Fe}_{x}(\mathrm{CO})_{y} ?\)
Problem 98
Group 2 A metal carbonates are decomposed to the metal oxide and \(\mathrm{CO}_{2}\) on heating: $$ \mathrm{MCO}_{3}(\mathrm{s}) \rightarrow \mathrm{MO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g}) $$ You heat 0.158 g of a white, solid carbonate of a Group \(2 \mathrm{A}\) metal \((\mathrm{M})\) and find that the evolved \(\mathrm{CO}_{2}\) has a pressure of \(69.8 \mathrm{mm}\) Hg in a \(285-\mathrm{mL}\) flask at \(25^{\circ} \mathrm{C} .\) Identify \(\mathrm{M}\).
Problem 99
One way to synthesize diborane, \(\mathrm{B}_{2} \mathrm{H}_{6}\), is the reaction \(\begin{aligned} 2 \mathrm{NaBH}_{4}(\mathrm{s})+2 \mathrm{H}_{3} \mathrm{PO}_{4}(\ell) & \rightarrow \\ \mathrm{B}_{2} \mathrm{H}_{6}(\mathrm{g})+& 2 \mathrm{NaH}_{2} \mathrm{PO}_{4}(\mathrm{s})+2 \mathrm{H}_{2}(\mathrm{g}) \end{aligned}\) (a) If you have \(0.136 \mathrm{g}\) of \(\mathrm{NaBH}_{4}\) and excess \(\mathrm{H}_{3} \mathrm{PO}_{4},\) and you collect the resulting \(\mathrm{B}_{2} \mathrm{H}_{6}\) 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 by-product of the reaction is \(\mathrm{H}_{2}\) gas. If both \(\mathrm{B}_{2} \mathrm{H}_{6}\) and \(\mathrm{H}_{2}\) gas come from this reaction, what is the total pressure in the \(2.75-\mathrm{L}\) flask (after reaction of 0.136 g of NaBH_with excess \(\left.\mathrm{H}_{3} \mathrm{PO}_{4}\right)\) at \(25^{\circ} \mathrm{C} ?\)
Problem 100
You are given a solid mixture of \(\mathrm{NaNO}_{2}\) and \(\mathrm{NaCl}\) and are asked to analyze it for the amount of NaNO_ present. To do so, you allow the mixture to react with sulfamic acid, \(\mathrm{HSO}_{3} \mathrm{NH}_{2}\), in water according to the equation \(\begin{aligned} \operatorname{NaNO}_{2}(\mathrm{aq})+\mathrm{HSO}_{3} \mathrm{NH}_{2}(\mathrm{aq}) \rightarrow & \\ \mathrm{NaHSO}_{4}(\mathrm{aq}) &+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{N}_{2}(\mathrm{g}) \end{aligned}\) What is the weight percentage of \(\mathrm{NaNO}_{2}\) in \(1.232 \mathrm{g}\) of the solid mixture if reaction with sulfamic acid produces \(295 \mathrm{mL}\) of dry \(\mathrm{N}_{2}\) gas with a pressure of \(713 \mathrm{mm}\) Hg at \(21.0^{\circ} \mathrm{C} ?\)
Problem 104
A compound containing \(\mathrm{C}, \mathrm{H}, \mathrm{N},\) and \(\mathrm{O}\) is burned in excess oxygen. The gases produced by burning 0.1152 g are first treated to convert the nitrogen-containing product gases into \(\mathrm{N}_{2}\), and then the resulting mixture of \(\mathrm{CO}_{2}, \mathrm{H}_{2} \mathrm{O}, \mathrm{N}_{2},\) and excess \(\mathrm{O}_{2}\) is passed through a bed of \(\mathrm{CaCl}_{2}\) to absorb the water. The \(\mathrm{CaCl}_{2}\) increases in mass by \(0.09912 \mathrm{g} .\) The remaining gases are bubbled into water to form \(\mathrm{H}_{2} \mathrm{CO}_{3}\), and this solution is titrated with \(0.3283 \mathrm{M} \mathrm{NaOH} ; 28.81 \mathrm{mL}\) is required to achieve the second equivalence point. The excess \(\mathrm{O}_{2}\) gas is removed by reaction with copper metal (to give CuO). Finally, the \(\mathrm{N}_{2}\) gas is collected in a 225.0 -mL flask, where it has a pressure of \(65.12 \mathrm{mm} \mathrm{Hg}\) at \(25^{\circ} \mathrm{C} .\) In a separate experiment, the unknown compound is found to have a molar mass of \(150 \mathrm{g} / \mathrm{mol} .\) What are the empirical and molecular formulas of the unknown compound?
Problem 105
You have a gas, one of the three known phosphorus-fluorine compounds \(\left(\mathrm{PF}_{3}, \mathrm{PF}_{5},\right.\) and \(\mathrm{P}_{2} \mathrm{F}_{4}\) ). To find out which, you have decided to measure its molar mass. (a) First, you determine that the density of the gas is \(5.60 \mathrm{g} / \mathrm{L}\) at a pressure of 0.971 atm and a temperature of \(18.2^{\circ} \mathrm{C} .\) Calculate the molar mass and identify the compound. (b) To check the results from part (a), you decide to measure the molar mass based on the relative rates of effusion of the unknown gas and \(\mathrm{CO}_{2} .\) You find that \(\mathrm{CO}_{2}\) effuses at a rate of \(0.050 \mathrm{mol} / \mathrm{min},\) whereas the unknown phosphorus fluoride effuses at a rate of 0.028 mol/ min. Calculate the molar mass of the unknown gas based on these results.
Problem 107
A 1.0 -L flask contains 10.0 g each of \(\mathrm{O}_{2}\) and \(\mathrm{CO}_{2}\) at \(25^{\circ} \mathrm{C}\) (a) Which gas has the greater partial pressure, \(\mathrm{O}_{2}\) or \(\mathrm{CO}_{2}\), or are they the same? (b) Which molecules have the greater rms speed, or are they the same? (c) Which molecules have the greater average kinetic energy, or are they the same?
Problem 108
If equal masses of \(\mathrm{O}_{2}\) and \(\mathrm{N}_{2}\) are placed in separate containers of equal volume at the same temperature, which of the following statements is true? If false, explain why it is false. (a) The pressure in the flask containing \(\mathrm{N}_{2}\) is greater than that in the flask containing \(\mathrm{O}_{2}\) (b) There are more molecules in the flask containing \(\mathrm{O}_{2}\) than in the flask containing \(\mathrm{N}_{2}\).
Problem 109
You have two pressure-proof steel cylinders of equal volume, one containing \(1.0 \mathrm{kg}\) of \(\mathrm{CO}\) and the other containing \(1.0 \mathrm{kg}\) of acetylene, \(\mathrm{C}_{2} \mathrm{H}_{2}\) (a) In which cylinder is the pressure greater at \(25^{\circ} \mathrm{C}\) (b) Which cylinder contains the greater number of molecules?
