To determine boiling point, we have the equation: ΔT = mK; where ΔT refers to the boiling-point elevation, m refers to molality which is in the unit mol/kg, and K is the molal boiling-point elevation constant.
In this problem, water is the solvent and NaCl is the solute. Note that 100°C is the boiling point of water. We substitute the equation:
ΔT = (1.5 m)(0.512 °C/m)
ΔT = 0.768°C
This is the change in temperature. To find the boiling point of the whole solution, we add the boiling point of the solvent:
100°C + 0.768°C = 100.768°C ≈ 100.8°C
The answer is C.
