Answer:
1.60 is the van't Hoff factor for ammonium chloride in X.
Explanation:
![\Delta T_f=iK_f\times m](https://tex.z-dn.net/?f=%5CDelta%20T_f%3DiK_f%5Ctimes%20m)
...(1)
where,
=Elevation in boiling point =
i = van't Hoff factor
= Freezing point constant
m = molality
1) When 70.4 g of benzamide are dissolved in 850. g of a certain mystery liquid X.
Mass of benzamide = 70.4 g
Molar mass of benzamide = 121 g/mol
i = 1 (organic molecule)
Mass of liquid X = 850 g = 0.850 kg
= Freezing point constant of liquid X= ?
![\Delta T_f=2.7^oC](https://tex.z-dn.net/?f=%5CDelta%20T_f%3D2.7%5EoC)
Putting all value in a (1):
![2.7^oC=K_f\times \frac{70.4 g}{121 g/mol\times 0.850 kg}](https://tex.z-dn.net/?f=2.7%5EoC%3DK_f%5Ctimes%20%5Cfrac%7B70.4%20g%7D%7B121%20g%2Fmol%5Ctimes%200.850%20kg%7D)
![K_f=3.944 ^oC kg/mol](https://tex.z-dn.net/?f=K_f%3D3.944%20%5EoC%20kg%2Fmol%20)
2) When 70.4 g of ammonium chloride are dissolved in 850. g of a certain mystery liquid X.
Mass of ammonium chloride= 70.4 g
Molar mass of ammonium chloride = 53.5 g/mol
i = ? (ionic molecule)
Mass of liquid X = 850 g = 0.850 kg
![K_f=3.944 ^oC kg/mol](https://tex.z-dn.net/?f=K_f%3D3.944%20%5EoC%20kg%2Fmol)
![\Delta T_f=9.9^oC](https://tex.z-dn.net/?f=%5CDelta%20T_f%3D9.9%5EoC)
Putting all value in a (1):
![9.9^oC=i\times 3.944^oC kg/mol\times \frac{70.4 g}{53.5 g/mol\times 0.850 kg}](https://tex.z-dn.net/?f=9.9%5EoC%3Di%5Ctimes%203.944%5EoC%20kg%2Fmol%5Ctimes%20%5Cfrac%7B70.4%20g%7D%7B53.5%20g%2Fmol%5Ctimes%200.850%20kg%7D)
i = 1.6011 ≈ 1.60
1.60 is the van't Hoff factor for ammonium chloride in X.