Question

Complete the following statements by selecting the correct alternative from the choices given:
The modal freezing point constant of water is $1.86K$ $kg{mol}^{-1}$. Therefore, the freezing point of $0.1M$ $NaCl$ solution in water is expected to be:

• A. $-{1.86}^{o}C$
• B. $-{0.372}^{o}C$
• C. $-{0.186}^{o}C$
• D. $+{0.372}^{o}C$

Answer 1

The correct option is C $-{0.186}^{o}C$

The molal freezing point constant of water is 1.86K kg/mol. Therefore, the freezing point of 0.1M NaCl
solution in water is expected to be
−0.186 deg C.
$\Delta T_f=K_{f}m=1.86Kkg/mol\times 0.1m=0.186K={0.186}^{o}C$
Therefore, the freezing point $=0{}^{o}C-0.186{}^{o}C=-0.186{}^{o}C$