Question

What is the percentage concentration `"m/m"` of a `3.30*mol*L^-1` solution of potassium nitrate, for which `rho_"solution"=1.15*g*mL^-1`?

Answer 1

We want the quotient....`"mass of solute"/"mass of solution"xx100%`

Explanation:

And so we work out the quotient using a `1*mL` of solution....

And this has a mass of solute give by....

`1*mLxx10^-3*L*mL^-1xx3.30*mol*L^-1xx101.10* g*mol^-1=0.334*g`....

And so now we can work out the required concentration...

`(0.334*g)/(1*mLxx1.15*g*mL^-1)xx100%=29.0%`

I confess I didn't really follow your line of reasoning....we gots solution density, and concentration in terms of moles per litre....and then we can calculate `%"mass"/"mass"`...