Acids

70% acid is made from the same acid of two different concentrations. The amount of weaker acid to the stronger acid is in ratio 2:1.

What was the concentration of the weaker acid if the stronger had 91% concentration?

Correct answer:

c =  59.5 %

Step-by-step explanation:

$$\begin{gathered} \frac{a}{b}=\frac{2}{1} \\ ac+b\cdot 0.91=0.7(a+b) \\ 2\cdot c+1\cdot 0.91=0.7\cdot (2+1) \\ c=0.595=59.5\% \end{gathered}$$

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