Question

What should be the freezing point of aqueous solution containing $17$ g of $C_2{H}_{5}OH$ in $1000$ g of water $(K_f$ for water $={1.86}^o$C kg mol${}^{-1})?$

• A. $-{0.69}^{o}C$
• B. ${0.34}^{o}C$
• C. ${0.0}^{o}C$
• D. $-{0.34}^{o}C$

Answer 1

The correct option is A $-{0.69}^{o}C$

$△T_f=K_f\times \frac{w_B\times 1000}{m_B\times w_A}=1.86\times \frac{17\times 1000}{46\times 1000}=0.69$

$\therefore$ Freezing point of solution $=0-0.69=-{0.69}^{o}C$