Question

What is the percent concentration (%,m/v) after 250 ML of an 8% (m/v) NaOH solution is diluted with 750 ML of water?

Answer 1

$x\%(m/v)$ solution contains x grams of solute in 100 ml. of solution.

Thus, 250 ml of $8\% (m/v) NaOH$ solution contains $8/100*250=20 gms.$ of NaOH.

On adding, 750 ml. of water to this solution, volume of the solution becomes $250+750=1000ml.$

Thus, the new diluted solution contains 20 gms. of NaOH in 1000ml. of solution.

Thus, concentration in %(m/v) $=20/1000=2/100=2\%(m/v)$ . (Answer)