Chapter 21

Choose the strongest acid from each group. (a) $\mathrm{HClO},\mathrm{HBrO},\mathrm{HIO}$ (b) $\mathrm{HIO},{\mathrm{HIO}}_3,{\mathrm{HIO}}_4$ (c) $\mathrm{HIO},{\mathrm{HBrO}}_2,{\mathrm{HBrO}}_4$

What intermolecular forces are present in the following? (a) ${\mathrm{Cl}}_2$ (b) $\mathrm{HBr}$ (c) $\mathrm{HF}$ (d) ${\mathrm{HClO}}_4$ (e) ${\mathrm{MgI}}_2$

Write a balanced equation for the reaction of hydrofluoric acid with ${\mathrm{SiO}}_2$. What volume of $2.0\mathrm{M}\mathrm{HF}$ is required to react with one gram of silicon dioxide?

State the oxidation number of $\mathrm{N}$ in (a) ${\mathrm{NO}}_2^{-}$ (b) ${\mathrm{NO}}_2$ (c) ${\mathrm{HNO}}_3$ (d) ${\mathrm{NH}}_4{}^{+}$

Why does concentrated nitric acid often have a yellow color even though pure ${\mathrm{HNO}}_3$ is colorless?

Explain why (a) acid strength increases as the oxidation number of the central non- metal atom increases. (b) nitrogen dioxide is paramagnetic. (c) the oxidizing strength of an oxoanion is inversely related to $\mathrm{pH}$. (d) sugar turns black when treated with concentrated sulfuric acid.

The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine; ${\mathrm{ClO}}^{-}$ is reduced to ${\mathrm{Cl}}^{-}$. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3;{\mathrm{I}}_2$ is reduced to ${\mathrm{I}}^{-}$. The sodium thiosulfate is oxidized to sodium tetrathionate, ${\mathrm{Na}}_2{\mathrm{S}}_4{\mathrm{O}}_6$. In this analysis, potassium iodide was added in excess to $5.00\mathrm{mL}$ of bleach $(d=1.00\mathrm{g}/{\mathrm{cm}}^3)$. If $25.00\mathrm{mL}$ of $0.0700\mathrm{M}{\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$ was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of $\mathrm{NaClO}$ in the bleach?