Question

A solution has a concentration of 40 g.L-1

. We take 20 mL of this solution and add water. The

final volume is 40 mL. What's the new concentration? No calculations but you need to

justify​

Answer 1

Answer: The new concentration is 20 g/L

Explanation:

According to the dilution law,

$C_1V_1=C_2V_2$

where,

$C_1$ = concentration of stock solution = 40 g/L

$V_1$ = volume of stock solution = 20 ml = 0.02 L

$C_2$ = concentration of diluted solution= ?

$V_2$ = volume of diluted solution= 40 ml = 0.04 L  

$40g/L\times 0.02L=C_2\times 0.04L$

$C_2=20g/L$

Thus new concentration is 20 g/L