Please help with this question, I would appreciate if you could explain your work where it needs explaining.

Question

What is the molality of acetone in a solution composed of 255 g of acetone, (CH₃)₂CO, dissolved in 200 g of water?

Answer 1

Molality is expressed as moles of solute per kg of solvent. We are given the kg of solvent as 0.200 kg (which is the same as 200 g). Now we must find the moles of solute.

molar mass acetone (CH₃)₂CO = 58.08 g

255 g (CH₃)₂CO x 1 mol / 58.08 g = 4.39 moles

molality = 4.39 moles / 0.200 kg = 22.0 m