# How to calculate the mass of a component in battery acid based on the density and mass fraction?

Battery acid has a density of $\pu{1.285 g cm^-3}$ and contains $38\%$ by weight sulfuric acid. How many grams of pure sulfuric acid are contained in a liter of battery acid?

I just took $1.285 \times 0.38$ and got how many grams of sulfuric acid are in $\pu{1 cm^3}$ of battery acid. So now I just converted it into grams per liter and got $\pu{488.3 gL^-1}$ of sulfuric acid in battery acid. I'm not sure if I did it right though.

• Please have a look at this tutorial to acquaint yourself with the way math and chemical formulae can be nicely formatted on this site. – Philipp Sep 14 '14 at 5:06
• duplicate of math.stackexchange.com/questions/930540/… – RE60K Sep 14 '14 at 6:36
• Please do not cross-post your questions. It results in a duplication of efforts and wastes the time of the people that have answered it. – jonsca Sep 14 '14 at 10:36

## 1 Answer

Yes, you did do it correctly. However, I would refer you to the homework policy of this site.

$\textrm{density} = \frac{\textrm{mass}}{\textrm{volume}}$

$\textrm{mass}=\textrm{density} \times \textrm{volume} = 1.285 \times 1000=1285\ \textrm{g}$

Then you just multiply by 0.38 (which is the same as 38%) and you get the answer.

Just a note, next time you ought to phrase your question by asking about the specific topic of the question (e.g How do I calculate the mass given the percentage...... etcetc), rather than the question itself.