Question

Calculate the mass of urea $\left(N{H}_{2}CON{H}_2\right)$ required in making $2.5kg$ of $0.2$ molal aqueous solution.

Answer 1

$0.2\times 2.5=0.625$ moles of urea is required

no. of moles$=\frac{Mass}{Molarmass}$

we know that,

no. of moles$=0.625$ moles

Molar mass of urea$=14+2\times 1+12+16+14+2\times 1=60g/mol$

$\therefore$ Mass= No. of moles$\times$ Molar mass $=0.625\times 60$

$=37.5g$