Question

When $400$ g of a $20$% solution by weight was cooled, $60$ g of solute is precipitated. The percentage concentration of the remaining solution is $x\%$.

The value of $x$ is _______.

(Round figure the answer up to nearest integer value)

Answer 1

The original concentration was $20$%, therefore $80$g of solute was present originally.

When $60$g of solute was precipitated, only $20$g of solute is left. The remaining mass of solution $=340g$.

Therefore, the concentration becomes: $\frac{20\times 100}{340}=5.88$%.

Thus $x\%=5.88\%$

$\therefore x=5.88\approx 6$