# Osmotic pressure and stoichiometry

1. Apr 6, 2015

### Mia Vel

1. The problem statement, all variables and given/known data
When 0.32 weight/volume% of sucrose, MgSO4 and KNO3 mixture is dissolved in 997 g of H2O, the osmotic pressure at 25 deg Celsius is 1.25 atm. Calculate the mole fraction and mass percent composition of the original mixture if it contains 15% weight/weight KNO3.

2. Relevant equations

Osmotic pressure= Molarity x Gas constant x Temperature in Kelvin

3. The attempt at a solution
I was able to solve for the molarity of the solution. After it, I don't know what to do next. Can someone please teach me what the next step is and what is the role(meaning) of weight/volume % and weight/weight % in the problem? Thank you in advance. :)

2. Apr 6, 2015

### Staff: Mentor

I have no idea what it means.

3. Apr 9, 2015

### Mia Vel

My friend told me that when you multiply the given percentage by 100, you will get the total mass of the mixture. I am just not sure whether I should believe him or not.

4. Apr 9, 2015

### Staff: Mentor

Doesn't sound correct to me. 30% sulfuric acid doesn't always weight 3000 (and 3000 of what? stones? grams? ounces? pounds?).