Question

What is 5% (v/v) ethanol expressed in molarity? Mr ethanol 46.06 and density 0.789 g/mL

2M

0.9M

1.2M

1.5M

Answer 1

Molarity(M) = (w/Mwt)*1000/V

            = w/V*100*10 / Mwt

       Molarity(M)   = (w/V%)*10 / Mwt

       w = v*d

so that,     Molarity(M)   = (v*d/V%)*10 / Mwt

                                   = (v/V%)*d*10 / Mwt

           Molarity(M)      = (5*0.789*10)/46.06 = 0.856 M

        answer: 0.9 M