- #1
Qube
Gold Member
- 468
- 1
Homework Statement
The molality of an aqueous sodium nitrate solution is 2.14 m. What is the mole fraction of sodium nitrate?
Homework Equations
Molality = moles of solute / kg of solvent.
Mole fraction of A = moles of A / total number of moles (in this case, moles of solute + moles of solution).
The Attempt at a Solution
Assuming we have 1 kg of solvent, we can assume we have 2.14 moles of NaNO3.
Mole fraction of NaNO3 is therefore 2.14 / [(1000/18) + 2.14] = 0.0370.
1000/18 because 1000 grams of water is present and there are 18 grams per mole of water. The grams cancel out and yield moles of water.