Use VSEPR theory to predict the probable geometric structures of the molecules
(a) $\mathrm{O}_2 \mathrm{XeF}_2 ;$

Oxygen atoms are an important constituent of the thermosphere, a layer of the atmosphere with temperatures up to $1500 \mathrm{~K}$. Calculate the average translational kinetic energy of $\mathrm{O}$ atoms at $1500 \mathrm{~K}$.

Zn can reduce $\mathrm{NO}_3{ }^{-}$to $\mathrm{NH}_3(\mathrm{~g})$ in basic solution. (The following equation is not balanced.)

$$\begin{aligned} \mathrm{NO}_3{ }^{-}(\mathrm{aq})+\mathrm{Zn}(\mathrm{s})+& \mathrm{OH}^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \longrightarrow \\ & {\left[\mathrm{Zn}(\mathrm{OH})_4\right]^{2-}(\mathrm{aq})+\mathrm{NH}_3(\mathrm{~g}) } \end{aligned}$$

The $\mathrm{NH}_3$ can be neutralized with an excess of $\mathrm{HCl}(\mathrm{aq})$. Then, the unreacted $\mathrm{HCl}$ can be titrated with $\mathrm{NaOH}$. In this way a quantitative determination of $\mathrm{NO}_3{ }^{-}$can be achieved. A $25.00 \mathrm{~mL}$ sample of nitrate solution was treated with zinc in a basic solution. The $\mathrm{NH}_3(\mathrm{~g})$ was passed into $50.00 \mathrm{~mL}$ of $0.1500 \mathrm{M} \mathrm{HCl}$. The excess $\mathrm{HCl}$ required $32.10 \mathrm{~mL}$ of $0.1000 \mathrm{M} \mathrm{NaOH}$ for its titration. What was the $\left[\mathrm{NO}_3\right]$ in the original sample?

The photograph was taken after a few drops of a deep-purple acidic solution of $\mathrm{KMnO}_4(\mathrm{aq})$ were added to $\mathrm{NaNO}_3(\mathrm{aq})$ (left) and to $\mathrm{NaNO}_2$ (aq) (right). Explain the difference in the results shown.

Suppose that no attempt is made to separate the $\mathrm{H}_2(\mathrm{~g})$ and $\mathrm{O}_2(\mathrm{~g})$ produced by the electrolysis of water. What volume of a $\mathrm{H}_2-\mathrm{O}_2$ mixture, saturated with $\mathrm{H}_2 \mathrm{O}(\mathrm{g})$ and collected at $23^{\circ} \mathrm{C}$ and $755 \mathrm{mmHg}$, would be produced by electrolyzing $17.3 \mathrm{~g}$ water? Assume that the water vapor pressure of the dilute electrolyte solution is $20.5 \mathrm{mmHg}$.

In 1988, G. J. Schrobilgen, professor of chemistry at McMaster University in Canada, reported the synthesis of an ionic compound, $[\mathrm{HCNKrF}]\left[\mathrm{AsF}_6\right]$, which consists of $\mathrm{HCNKrF}^{+}$and $\mathrm{AsF}_6{ }^{-}$ions. In the $\mathrm{HCNKrF}^{+}$ ion, the krypton is covalently bonded to both fluorine and nitrogen. Draw Lewis structures for these ions, and estimate the bond angles.

The boiling points of oxygen and argon are $-183^{\circ} \mathrm{C}$ and $-189^{\circ} \mathrm{C}$, respectively. Because the boiling points are so similar, argon obtained from the fractional distillation of liquid air is contaminated with oxygen. The following three-step procedure can be used to obtain pure argon from the oxygen-contaminated sample:
(1) Excess hydrogen is added to the mixture and then the mixture is ignited.
(2) The mixture from step (1) is then passed over hot copper(II) oxide.
(3) The mixture from step (2) is passed over a dehydrated zeolite material
Explain the purpose of each step, writing chemical equations for any reactions that occur.

On the basis of molecular orbital theory, would you expect $\mathrm{NH}_2^{+}$to be linear or bent?

Use VSEPR theory to predict the probable geometric structures of
(c) $\mathrm{XeF}_5{ }^{+}$.

Use VSEPR theory to predict the probable geometric structures of
(b) $\mathrm{XeO}_4$;

Use VSEPR theory to predict the probable geometric structures of
(a) $\mathrm{XeO}_3$;

The amide anion $\mathrm{NH}_2{ }^{-}$is a very strong base. On the basis of molecular orbital theory, would you expect $\mathrm{NH}_2{ }^{-}$to be linear or bent?

How many grams of $\mathrm{CaH}_2(\mathrm{~s})$ are required to generate sufficient $\mathrm{H}_2(\mathrm{~g})$ to fill a $235 \mathrm{~L}$ weather observation balloon at $722 \mathrm{mmHg}$ and $19.7^{\circ} \mathrm{C}$ ?

$$\mathrm{CaH}_2(\mathrm{~s})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{I}) \longrightarrow \mathrm{Ca}(\mathrm{OH})_2(\mathrm{aq})+2 \mathrm{H}_2(\mathrm{~g})$$

Without doing detailed calculations, explain in which of the following materials you would expect to find the greatest mass percent of hydrogen: seawater, the atmosphere, natural gas $\left(\mathrm{CH}_4\right)$, ammonia.