The molality of a solution is a measure of the concentration of solute particles in a solvent. It is defined as the number of moles of solute per kilogram of solvent. In order to find the molality of a semi molar NaCl (sodium chloride) solution, we need to know the density of the solution.

Density of the Solution:
The given density of the solution is 1.16 g/cm³.

Calculating the Mass of the Solution:
To calculate the mass of the solution, we need to consider the volume and density. Let's assume we have 1 liter (1000 cm³) of the solution.

Mass of the solution = Volume × Density
= 1000 cm³ × 1.16 g/cm³
= 1160 g

Moles of Sodium Chloride (NaCl):
Since the solution is semi molar, it means it contains half a mole of NaCl (solute) in 1 liter of solution.

Moles of NaCl = 0.5 mol

Calculating the Mass of NaCl:
The molar mass of NaCl is 58.44 g/mol. Using this, we can calculate the mass of NaCl in the solution.

Mass of NaCl = Moles of NaCl × Molar mass of NaCl
= 0.5 mol × 58.44 g/mol
= 29.22 g

Molality:
Molality is defined as moles of solute per kilogram of solvent. In this case, the solvent is water.

Since the mass of the solution is 1160 g and the mass of NaCl is 29.22 g, we can calculate the mass of water (solvent).

Mass of water = Mass of solution - Mass of NaCl
= 1160 g - 29.22 g
= 1130.78 g

Now, we can calculate the molality using the moles of NaCl and the mass of water.

Molality = Moles of NaCl / Mass of water (kg)
= 0.5 mol / 1.13078 kg
≈ 0.442 mol/kg

Therefore, the molality of the semi molar NaCl solution is approximately 0.442 mol/kg.