Answer:
0.787 mol.Kg⁻¹ or 0.787 m
Explanation:
Data Given:
Mass = m = 75.8 g
Volume = V = 1.55 L = 1550 mL
M.Mass of Ethylene Glycol = 62.07 g/mol
Density of water = d = 1.0 g/mL
To Find:
Molality = ??
Molality is a unit of concentration and is defined as the number of moles of solute per Kg of a solvent.
Molality = Moles of Solute / Kg of Solvent --- (1)
First Calculate Moles of Solute as;
Moles = Mass / M.Mass
Moles = 75.8 g / 62.07 g/mol
Moles = 1.22 moles
Secondly calculate mass of water as,
mass of water = density × volume
mass of water = 1.0 g/mL × 1550 mL
mass of water = 1550 g or 1.55 Kg
Now, putting values of moles and mass of solvent in equation 1,
Molality = 1.22 mol / 1.55 Kg
Molality = 0.787 mol.Kg⁻¹ or 0.787 m
