Chapter 7.7, Problem 9P

To determine

To Find: Amount of water must be added in the solution

Answer to Problem 9P

  $25l$

Explanation of Solution

Given:

  $$

  $\begin{array}{l}\text{Solution: }50l\\ \text{initial acid solution: }30\%\\ \text{final acid solution: }20\%\end{array}$

Formula Used:

  $\text{Total amount }\times \text{ \% content = Amount}$

Calculation:

  $\begin{array}{l}\text{let the amount of water added in the solution be: }x\\ \text{Acid solution: }50\times 0.3=15\\ \text{Water: }x\times 0=0\\ \text{Mixture: }0.20\left(50+x\right)\\ \Rightarrow 15=0.20\left(50+x\right)\\ \Rightarrow 15=10+0.2x\\ \Rightarrow 5=0.2x\\ \Rightarrow 25=x\end{array}$

Conclusion:

Thus the amount of water added in the solution is: $25l$