What is the molality of a solution containing 15.0g NaCl dissolved in 50.0g water?

Hey there!

Molar mass NaCl = 58.44 g/mol

number of moles:

n = m / mm

n = 15.0 / 58.44

n = 0.2566 moles of NaCl

Volume in Kg:

50.0 g / 1000 = > 0.05 Kg

Therefore:

Molality = moles of solute / volume

Molatity = 0.2566 / 0.05

Molality = 5.132 mol/kg