Chapter 13

Te analysis of \(0.922 \mathrm{~g}\) of aniline, a common organic base used in some varnishes, is \(0.714 \mathrm{~g} \mathrm{C}\), \(0.138 \mathrm{~g} \mathrm{~N}\), and the remainder hydrogen. What is the empirical formula of aniline?

Urea is used as a commercial fertilizer because of its nitrogen content. An analysis of \(25.0 \mathrm{mg}\) of urea showed that it contained \(5.0 \mathrm{mg} \mathrm{C}, 11.68 \mathrm{mg} \mathrm{N}\), \(6.65 \mathrm{mg} \mathrm{O}\), and the remainder hydrogen. What is the empirical formula of urea?

Small amounts of chlorine gas can be generated in the laboratory from the reaction of manganese(IV) oxide with hydrochloric acid: \(4 \mathrm{HCl}(\mathrm{aq})+\mathrm{MnO}_{2}(\mathrm{~s})\) \(\rightarrow 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+\mathrm{MnCl}_{2}(\mathrm{~s})+\mathrm{Cl}_{2}(\mathrm{~g})\). (a) What mass of \(\mathrm{Cl}_{2}\) can be produced from \(42.7 \mathrm{~g}\) of \(\mathrm{MnO}_{2}\) with an excess of HCl(aq)? (b) What volume of chlorine gas (of density \(3.17 \mathrm{~g} \cdot \mathrm{L}^{-1}\) ) will be produced from the reaction of \(300 \mathrm{~mL}\) of \(0.100 \mathrm{M} \mathrm{HCl}(\mathrm{aq})\) with an excess of \(\mathrm{MnO}_{2}\) ? (c) Suppose only \(150 \mathrm{~mL}\) of chlorine was produced in the reaction in (b). What is the percentage yield of the reaction?