Question

A scientist needs 120 milliliters of a 20% acid solution for an experiment. The lab has available a 25% and a 10% solution. How many liters of the 25% and how many liters of the 10% solutions should the scientist mix to make the 20% solution?

Answer 1

Answer:

the required quantity of solution of 10%  is 40 ml

the required quantity of solution of 25%  = 80 ml

Explanation:

let the required quantity of solution of 10% be x

and quantity of solution of 25% be (120 - x) ml

Hence, quantity of acid in x ml of 10 percentage solution is$x\times 10%$and similarly for 25% solution be $( 120-x) \times 25\%$

therefore total amount of acid is $x\times 10\% + ( 120-x) \times 25\%$

we  need total solution of 120 ml of 20% so we have

$x\times 10\% + ( 120-x) \times 25\% = 120 \times 20\%$

after solving we get

$\frac{x}{10} -\frac{x}{4} = 24 - \frac{120}{4}$

solving for x we get

x = 40

therefore ,

the required quantity of solution of 10%  is 40 ml

the required quantity of solution of 25%  = 80 ml