Water contains about 42 mg of oxygen per liter at 20 $\degree$C and 1 atm.What is the Henry's law constant for oxygen dissolving in water?

Question

Quizplus · Accepted Answer

Henry's law states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid. The constant for this relationship is Henry's law constant. Given 42 mg of O2 per liter, we first convert this to moles (since 1 mole of O2 = 32 g):$$42 \, \text{mg} = 0.042 \, \text{g} = \frac{0.042 \, \text{g}}{32 \, \text{g/mol}} = 0.0013125 \, \text{mol/L}$$At 1 atm, the Henry's law constant (k) can be calculated as:$$k = \frac{C}{P} = \frac{0.0013125 \, \text{mol/L}}{1 \, \text{atm}} = 1.3 \times 10^{-3} \, \text{mol/L} \cdot \text{atm}$$This matches choice B when considering the correct scientific notation and unit conversion.

Water Contains About 42 Mg of Oxygen Per Liter at 20