Math CentralQuandaries & Queries


Question from Tan:

How much 96% $H_2 SO_4$ to add into sulphuric acid 30% in order to make it to 50%

sulphuric acid?

Hi Tan,

Suppose you add $X$ ml of 96% sulphuric acid then you will be adding $0.96 \times x$ ml of pure acid.

Suppose you add it to $Y$ ml of 30% sulphuric acid which contains $0.30 \times Y$ pure acid.

You then have $X + Y$ ml of a mixture which you want to be 50% pure acid. Hence

\[0.96 X + 0.30 Y = 0.50 (X + Y).\]

If you know $Y$ you can solve for $X.$

Write back if you need more assistance,

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