Problem 76
Argon gas is inert, so it poses no serious health risks. However, if significant amounts of radon are inhaled into the lungs, lung cancer is a possible result. Explain the health risk differences between argon gas and radon gas.
Problem 77
There is evidence that radon reacts with fluorine to form compounds similar to those formed by xenon and fluorine. Predict the formulas of these \(\operatorname{Rn} \mathrm{F}_{x}\) compounds.
Problem 80
The inert-pair effect is sometimes used to explain the tendency of heavier members of Group 3 \(\mathrm{A}\) to exhibit \(+1\) and \(+3\) oxidation states. What does the inert-pair effect reference? (Hint:Consider the valence electron configuration for Group 3 \(\mathrm{A}\) elements.)
Problem 81
How could you determine experimentally whether the compound \(\mathrm{Ga}_{2} \mathrm{Cl}_{4}\) contains two gallium(Il) ions or one gallium(I) and one gallium(III) ion? (Hint: Consider the electron configurations of the three possible ions.)
Problem 82
The resistivity (a measure of electrical resistance) of graphite is \((0.4 \text { to } 5.0) \times 10^{-4}\) ohm \(\cdot \mathrm{cm}\) in the basal plane. (The basal plane is the plane of the six-membered rings of carbon atoms.) The resistivity is 0.2 to 1.0 ohm \(\cdot \mathrm{cm}\) along the axis perpendicular to the plane. The resistivity of diamond is \(10^{14}\) to \(10^{16} \mathrm{ohm} \cdot \mathrm{cm}\) and is independent of direction. How can you account for this behavior in terms of the structures of graphite and diamond?
Problem 83
When sodium reacts with hydrogen gas, sodium hydride is produced. Is sodium hydride an ionic or a covalent compound? When sodium hydride reacts with water, the equation is: $$ \mathrm{NaH}(s)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{Na}^{+}(a q)+\mathrm{OH}^{-}(a q)+\mathrm{H}_{2}(g) $$ Show that this reaction can be considered both an oxidationreduction reaction and an acid-base reaction.
Problem 84
EDTA is used as a complexing agent in chemical analysis. Solutions of EDTA, usually containing the disodium salt \(\mathrm{Na}_{2} \mathrm{H}_{2} \mathrm{EDTA}\) , are also used to treat heavy metal poisoning. The equilibrium constant for the following reaction is \(6.7 \times 10^{21} :\) Calculate \(\left[\mathrm{Pb}^{2+}\right]\) at equilibrium in a solution originally 0.0050 \(\mathrm{M}\) in \(\mathrm{Pb}^{2+}, 0.075 M\) in \(\mathrm{H}_{2} \mathrm{EDTA}^{2-},\) and buffered at \(\mathrm{pH}=7.00 .\)
Problem 85
Photogray lenses contain small embedded crystals of solid silver chloride. Silver chloride is light-sensitive because of the reaction $$ \mathrm{AgCl}(s) \stackrel{\mathrm{hv}}{\longrightarrow} \mathrm{Ag}(s)+\mathrm{Cl} $$ Small particles of metallic silver cause the lenses to darken. In the lenses this process is reversible. When the light is removed, the reverse reaction occurs. However, when pure white silver chloride is exposed to sunlight it darkens; the reverse reaction does not occur in the dark. a. How do you explain this difference? b. Photogray lenses do become permanently dark in time. How do you account for this?
Problem 86
Hydrazine is somewhat toxic. Use the following half-reactions to explain why household bleach (highly alkaline solutions of sodium hypochlorite) should not be mixed with household ammonia or glass cleansers that contain ammonia. $$ \mathrm{ClO}^{-}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{OH}^{-}+\mathrm{Cl}^{-} \quad \mathscr{E}^{\circ}=0.90 \mathrm{V} $$ $$ \mathrm{N}_{2} \mathrm{H}_{4}+2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{NH}_{3}+2 \mathrm{OH}^{-} \quad \mathscr{E}^{\circ}=-0.10 \mathrm{V} $$
Problem 87
The compound with the formula TII_ is a black solid. Given the following standard reduction potentials, \(\mathrm{T} 1^{3+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Tl}^{+}\) \(\mathscr{E}^{\circ}=1.25 \mathrm{V}\) \(\mathrm{I}_{3}^{-}+2 \mathrm{e}^{-} \longrightarrow 3 \mathrm{I}^{-}\) \(\mathscr{E}^{\circ}=0.55 \mathrm{V}\)
