# A 30% solution of ethyl alcohol in water at 20° C has a density of 0.95g/mL. What weight of alcohol is combined in 750 mL of solution?

Aug 6, 2017

It is always a problem when a $\text{% concentration}$ is specified. I get $214 \cdot g$ with respect to $\text{ethyl alcohol}$.

#### Explanation:

Do you mean $\text{Mass of solute"/"Mass of solution}$ or $\text{Volume (or mass) of solute"/"Volume of solution}$?

Given the context of the question, I ASSUME that you mean.....

"Mass of ethyl alcohol"/"Mass of solution"xx100%=30%.

We are further given that..........................

$\rho = \text{mass of solution"/"volume of solution} = 0.95 \cdot g \cdot m {L}^{-} 1$.

And so we work from a $750 \cdot m L$ $\text{volume}$, which has a mass of $750 \cdot m L \times 0.95 \cdot g \cdot m {L}^{-} 1 = 712.5 \cdot g$. Agreed?

And by specification, 30% of this mass is $\text{ethyl alcohol}$, i.e. 30%xx712.5*g=213.75*g WITH RESPECT TO $\text{ethyl alcohol}$. This is the approx. concentration of a whisky, distilled beer, or a brandy or grappa, distilled wine.