91Ó°ÊÓ

Why does the solubility of any gas in water decrease with rising temperature?

For a saturated aqueous solution of each of the following at ${\mathbf{20}}^{\mathbf{o}}\mathbf{C}$ and 1atm, will the solubility increase, decrease, or stay the same when the indicated change occurs?

(a)${\mathbf{O}}_{\mathbf{2}}\left(\mathbf{g}\right)$, increase P

(b)${\mathbf{N}}_{\mathbf{2}}\left(\mathbf{g}\right)$, increase V

For a saturated aqueous solution of each of the following at and 1atm, will the solubility increase, decrease, or stay the same when the indicated change occurs?

(a)He(g), decrease T

(b)RbI(s), increase P

The Henry’s law constant (k_H) for ${\mathbf{O}}_{\mathbf{2}}$ in water at ${\mathbf{20}}^{\mathbf{o}}\mathbf{C}$ in $\mathbf{1}\mathbf{.}\mathbf{28}\mathbf{×}{\mathbf{10}}^{\mathbf{-}\mathbf{3}}{\mathbf{molL}}^{\mathbf{-}\mathbf{1}}{\mathbf{atm}}^{\mathbf{-}\mathbf{1}}$.

(a) How many grams of ${\mathbf{O}}_{\mathbf{2}}$will dissolve in 2.50 L of ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ that is in contact with pure ${\mathbf{O}}_{\mathbf{2}}$ at 1.00 atm?

(b) How many grams of ${\mathbf{O}}_{\mathbf{2}}$will dissolve in 2.50 L of localid="1659159513018" ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ that is in contact with air, where the partial pressure of is 0.209 atm?

Caffeine is about 10 times as soluble in hot water as in cold water. A chemist puts a hot-water extract of caffeine into an ice bath, and some caffeine crystallizes. Is the remaining solution saturated, unsaturated, or supersaturated?

The partial pressure of ${\mathbf{CO}}_{\mathbf{2}}$ gas above the liquid in a bottle of champagne at ${\mathbf{20}}^{\mathbf{o}}\mathbf{C}$is 5.5 atm. What is the solubility of ${\mathbf{CO}}_{\mathbf{2}}$ in champagne? Assume Henry’s law constant is the same for champagne as for water: at ${\mathbf{20}}^{\mathbf{o}}\mathbf{C}$, $\mathbf{KH}\mathbf{=}\mathbf{3}\mathbf{.}\mathbf{7}\mathbf{×}{\mathbf{10}}^{\mathbf{-}\mathbf{2}}\mathbf{mol}\text{/}\mathbf{L}·\mathbf{atm}$.

Which would you expect to be more effective as soap, sodium acetate, or sodium stearate? Explain.

Respiratory problems are treated with devices that deliver air with a higher partial pressure of ${\text{O}}_{\text{2}}$ than normal air. Why?

Explain the difference between molarity and molality. Under what circumstances would molality be a more accurate measure of the concentration of a prepared solution than molarity? Why?

Which way of expressing concentration includes

1. volume of solution;
2. mass of solution;
3. mass of solvent?