Answer:
n(NaCl) = 20.9 mol
Step-by-step explanation:
To determine the number of moles of NaCl in the solution, we need to use the definition of molality, which is defined as the number of moles of solute per kilogram of solvent.
We are given the mass of the solution (115 kg) and the molality of the sodium chloride solution (0.250 m), which means that there are 0.250 moles of NaCl for every kilogram of solvent.
We need to determine the mass of solvent in the solution, which is given by:
mass of solvent = total mass of solution - mass of solute
The mass of solute (NaCl) is not given explicitly, but we can calculate it using the molality and the mass of solvent. We have:
0.250 m = 0.250 moles of NaCl / 1 kg of solvent
Therefore, the number of moles of NaCl in 115 kg of solution is:
moles of NaCl = molality x mass of solvent
mass of solvent = total mass of solution - mass of solute
mass of solvent = 115 kg - (115 kg x 0.250 mol/kg x 58.44 g/mol)
mass of solvent = 83.5 kg
moles of NaCl = 0.250 mol/kg x 83.5 kg
moles of NaCl = 20.9 moles
Therefore, there are 20.9 moles of NaCl in 115 kilograms of a 0.250 m sodium chloride solution.