posted by ieshia .
Use Henry's law and the solubilities given below to calculate the total volume of nitrogen and oxygen gas that should bubble out of 1.1L of water upon warming from 25 ∘C to 50 ∘C. Assume that the water is initially saturated with nitrogen and oxygen gas at 25 ∘C and a total pressure of 1.0 atm. Assume that the gas bubbles out at a temperature of 50 ∘C. The solubility of oxygen gas at 50 ∘C is 27.8 mg/L at an oxygen pressure of 1.00 atm. The solubility of nitrogen gas at 50 ∘C is 14.6 mg/L at a nitrogen pressure of 1.00 atm. Assume that the air above the water contains an oxygen partial pressure of 0.21 atm and a nitrogen partial pressure of 0.78 atm.
chem 102 -
p = KcC
p = 0.21 when saturated and Kc = about 769 atm*L/mol but you should look this up in your tables and use that number here. Also, I have estimated all of my other answers; you definitely should go through the calculations yourself and refine each of the steps.
C for the sat'd solution at 25C is
about 3E-4M. Convert that to mol.
3E-4 mols/L x 1.1 L = about 3E-4 mols and that x 32 = about 9.5E-3 g which is about 9.5 mg in the 1.1 L @ 25C for O2.
At 50C, oxygen is 27.8 mg/L @ 1atm or
27.8mg/L x 1.1 L = about 30 mg @ 1 atm. If the pressure is to be 0.21 above the solution at equilibrium the solubility will be decreased to about 30 x 0.21 atm/1 atm = about 6.5 mg. So 9.5mg initially - 6.5 mg at 50C is about 3 mg O2 that should bubble out.
N2 can be done the same way, then add the partial pressure of O2 to that of N2 to find total P. Check my thinking.