Open Question
Use Henry’s Law to determine the molar solubility of helium at a pressure of 1.0 atm and 25 °C.
14. Solutions
Henry's Law Calculations
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Calculate the mass of oxygen (in mg) dissolved in a 5.00 L bucket of water exposed to a pressure of 1.13 atm of air. Assume the mole fraction of oxygen in air to be 0.21 and the Henry's law constant for oxygen in water at this temperature to be 1.3 × 10⁻³ mol/L·atm.
A
10.2 mg
B
7.7 mg
C
5.5 mg
D
3.3 mg
Verified step by step guidance1
Start by understanding Henry's Law, which states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid. The formula is: , where is the concentration of the gas, is Henry's law constant, and is the partial pressure of the gas.
Calculate the partial pressure of oxygen in the air using the mole fraction. The partial pressure is given by: , where is the mole fraction of oxygen (0.21) and is the total pressure (1.13 atm).
Use Henry's Law to find the concentration of dissolved oxygen in water. Substitute the values into the formula: .
Calculate the number of moles of oxygen dissolved in the 5.00 L of water using the concentration from Henry's Law: .
Convert the moles of oxygen to mass in milligrams. Use the molar mass of oxygen (32.00 g/mol) to find the mass: . Then convert grams to milligrams by multiplying by 1000.
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