Question by djjjjs2000: How do you find the mass percentage of a solute given the solute’s density and the solution’s Molarity?
Hi, I tutor basic college chem and came across a student with a question I couldn’t answer.

A solution of water and sulfuric acid(H2SO4) has a Molarity of 18.3 . Given that the density of sulfuric acid is 1.84 g/ml, calculate the mass percentage of the sulfuric acid.

I’ve been racking my brains but can’t come up with the prof answer of 97.5%

Can anyone step me through this?

Best answer:

Answer by idq000@prodigy.net
Hello! I just finsihed AP Chemistry last year, and I am glad that I can help you out on this problem!

You have a solution that is 18.3 M. The density of the solution is 1.84g/mL. Convert the density of the solution into g/L by multiplying top and bottom by 1000. You should get 1840 g/L. Convert the top into moles of H2SO4. You should find that the solution, if pure, would be 18.7755 M or aournd 18.78 M solution. All you have to do is just divide the 18.3 M by 18.78, and you should get an answer around 97.5%.

I hope I helped!
idq000

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