Chemistry
posted by Luc on .
Calculate the molality (m) of a 6.56 kg sample of a solution of the solute acetone dissolved in the solvent ethanol if the sample contains 1.44 kg of acetone.
Additional info:
Molar Mass (g/mol)
acetone = 58.05
ethanol = 46.07
Density (g/mL)
acetone = 0.7899
ethanol = 0.7893
Dr. Bob, I asked a question like this about molality and the step by step explanation that you provided helped greatly. Could you please help me out with this one. It is slightly different and I'm really confused. Thank you!

never mind, I figured it out. I'll post the explanation just in case anyone else needs help with a similar problem.
Equation:
molality acetone = mol acetone/kg ethanol

to find kg ethanol:
total mass  sample mass of acetone
(6.56kg  1.44kg) = 5.12kg ethanol

to find mol acetone:
convert kg to g of sample mass given
(1.44kg x 1000g/kg) = 1440g acetone
divide sample mass(grams) by molar mass
(1440g / 58.05g)= 24.80620155mol acetone

Plug in answers to formula:
Molality = 24.80620155 mol acetone/ 5.12kg ethanol 
I didn't go through the math but this looks ok to me.