Question

$1\%$ aqueous solution of $Ca(N{O}_3{)}_2$ has freezing point:

• A. $0^o$C
• B. less than $0^o$C
• C. $1^o$C
• D. $2^o$C

Answer 1

The correct option is B less than $0^o$C

The freezing point depression can be calculated by a formula

$\Delta T_f=i{K}_{f}b$

$\Delta T_f=T_f^o-Tf=$ the depression of freezing point.

$i=$ the van't hoff factor =3

$K_f=$ Molar freezing depression constant = 1.86kg/mol

$b=$ molar concentration of the solution = 0.062 mol/kg

$\delta T_f=3\times 1.86\times 0.062={0.34}^{o}C$

$T_f=T_f^o-{0.34}^o=-{0.34}^o$