chemistry
posted by Monique on .
If im given mass percent and mass solvent how do I find mass solute and mass solution.
example: Mass percent = 3.8% and Mass solvent 45.8 g.
Find mass solute and mass solution

You can do it one of two ways but both are mathematically the same.
Let X = mass solute.
(X)/(X+45.8) = 0.038 and solve for X.
X = solute and
X+45.8 = mass soln.
The other way is just as easy.
3.80% w/w means 3.80g solute/100 g soln = 3.80g/(3.80+96.2)
Since you have 45.8 g solvent, then
3.80 x (45.8/96.3) = 1.809g solute (I know that's too many significant figures).
You can check that.
[1.809/(1.809+45.8)]*100 = 3.80%
mass soln = 1.809+45.8 = ? 
where did you get the 96.2

A 3.80% w/w solution means 3.80 g solute in 100 g soln. The 100 g solution consists of 3.80 g solute and water(solvent) so the solvent must be 1003.80 = 96.2g.