Understanding Henry's Law
Henry's Law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. Mathematically:
* C = kP
Where:
* C is the concentration of the dissolved gas (in mol/L)
* k is Henry's Law constant (in mol/(L·atm))
* P is the partial pressure of the gas (in atm)
Calculations
1. Apply Henry's Law:
* We have the partial pressure of oxygen (P = 0.21 atm) and Henry's constant (k = 0.0013 mol/(L·atm)).
* Substitute these values into Henry's Law equation to find the concentration (C):
* C = (0.0013 mol/(L·atm)) * (0.21 atm) = 0.000273 mol/L
2. Calculate Moles of Oxygen:
* We know the concentration of oxygen in the water (C = 0.000273 mol/L) and the volume of water (45 L).
* To find the total moles of dissolved oxygen, multiply the concentration by the volume:
* Moles of Oxygen = (0.000273 mol/L) * (45 L) = 0.012285 moles
Therefore, approximately 0.012285 moles of oxygen will dissolve in 45 liters of water at 20°C with a partial pressure of 0.21 atm.
