313,008 views
39 votes
39 votes
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

User Mosheh
by
3.1k points

1 Answer

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

Molarity


\\ \tt\hookrightarrow (1.3)/(0.42)=3.09M

Now


\\ \tt\hookrightarrow \Delta T=K_f* m* i

  • m is Molarity
  • I is vant Hoff factor


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

User Karolba
by
3.2k points