Question

The solubility of oxygen gas in water at 40 °C is 1.0 mmol/L of solution. What is this concentration in units of mole fraction? Density of water is 0.9981 g/mL at this temperature.

A) 1.00 x 10⁻⁶
B) 1.80 x 10⁻⁵
C) 1.80 x 10⁻²
D) 1.00 x 10⁻²
E) 5.55 x 10⁻²

Answer 1

The concentration of oxygen gas in units of mole fraction is approximately 1.80 x 10⁻⁵

Step-by-step explanation:

The solubility of a gas in a liquid can be determined using Henry's Law, which states that the mole fraction of the gas in the liquid is directly proportional to the partial pressure of the gas above the liquid. The Henry's Law constant, k, is the proportionality constant that relates the mole fraction to the partial pressure. In this case, we can use the Henry's Law equation: mole fraction of oxygen = (partial pressure of oxygen) / (Henry's Law constant). Given that the solubility of oxygen gas in water at 40 °C is 1.0 mmol/L of solution and the density of water at this temperature is 0.9981 g/mL, we can calculate the mole fraction of oxygen gas in water as follows:

mole fraction of oxygen = (1.0 mmol/L) / [(0.9981 g/mL) * (1 L/1000 mL) * (32 g/mol)]

After calculating the mole fraction, we find that the concentration of oxygen gas in units of mole fraction is approximately 1.80 x 10⁻⁵.