Question

5 points
15. Given the formula below: What is the change in the water's freezing
point when 75 grams of NaCl is added to 400 grams of H20? (Kf water -
1.86 C/m) *
Change in Temp = - ix K, x m
- 0.119 ° C
- 1.19 ° C
O A
B.
- 11.9°C
- 119°C
C

Answer 1

• Moles of NaCl:-75/58=1.3mol
• Volume of H_2O=0.420L

Molarity

$\\ \tt\hookrightarrow \dfrac{1.3}{0.42}=3.09M$

Now

$\\ \tt\hookrightarrow \Delta T=K_f\times m\times i$

• m is Molarity
• I is vant Hoff factor

$\\ \tt\hookrightarrow \Delta T=1.86(3.09)(2)=11.5°C$