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?

1 Answer
anor277
Aug 6, 2017

It is always a problem when a #"% concentration"# is specified. I get #214*g# with respect to #"ethyl alcohol"#.

Explanation:

Do you mean #"Mass of solute"/"Mass of solution"# or #"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="mass of solution"/"volume of solution"=0.95*g*mL^-1#.

And so we work from a #750*mL# #"volume"#, which has a mass of #750*mLxx0.95*g*mL^-1=712.5*g#. Agreed?

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

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