Respuesta :
Answer:
[CaCl₂·2H₂O] = 1.43 m
Explanation:
Molality is mol of solute / kg of solvent.
Mass of solvent = 40 g
Let's convert g to kg → 40 g / 1000 = 0.04 kg
Let's determine the moles of solute (mass / molar mass)
8.43 g / 146.98 g/mol = 0.057 mol
Molality = 0.057 mol / 0.04 kg → 1.43
Answer:
The answer to your question is molality = 1.36 ≈ 1.4
Explanation:
Data
mass CaCl₂ 2H₂O= 8.43 g
mass of water = 40 g
molality = ?
Process
1.- Calculate the molecular mass of CaCl₂ 2H₂O
CaCl₂ 2H₂O = 40 + 71 + 4 + 32 = 147 g
Calculate the moles of CaCl₂ 2H₂O
147 g ----------------- 1 mol
8.43 g -------------- x
x = (8.43 x 1) / 147
x = 0.057 moles
2.- Calculate the mass of H₂O in the solute
147 g of CaCl₂ 2H₂O ------------ 36 g of H₂O
8.43 g CaCl₂ 2H₂O ------------ x
x = (8.43 x 36) / 147
x = 303.48 / 147
x = 2.06 g of H₂O
3.- Total mass of water
mass of water = 2.06 + 40
= 42.06 g
4.- Calculate molality
molality = number of moles / mass of solvent (kg)
molality = 0.057 / 0.0421
molality = 1.4