Suppose you had 58.44 g of NaCl and you dissolved it in exactly 2.00 L of water. What would be the molality?
The molality can be calculated using the following equation:
M = n(solute)/m(solvent)
where n - moles of solute, m mass of solvent (kg)
n(NaCl) = m(NaCl) / Mr(NaCl) = 58.44 g / 58.44 g/mol = 1 mol
From here, the molality of the solution is:
M(NaCl) = n(NaCl) / m(H2O) = 1 mol / 2 kg = 0.5 mol/kg
Answer: 0.5 mol/kg