[mac227]

How much would it cost to make a 2.5 kg 5 m (molality) solution of AlCl3 ($50 per 500 kg)?

Where do I begin?

[Nobby]

How to begin?

first get molecular weight of AlCl₃. Then calculate what is the mass of 5 m of this salt. This is the value to make 1 kg. Then calculate how much you need for 2.5 kg. From the pricing you know 500 kg cost 50 bucks, what means 10 kg would cost 1 $.

[Borek]

Then calculate what is the mass of 5 m of this salt. This is the value to make 1 kg.

No. Reread the definition of molality.

mac: Nobby's path is close to correct one, just check why he is wrong.

[mac227]

AlCl3 is 133.34 g/mol.          I need 2.5 kg of a 5 m (moles of solute/kg solvent) solution.

So if I have 25 moles of AlCl3 and add that too 5 kg of water (my solvent)  I get a 5 m solution correct?

[Borek]

AlCl3 is 133.34 g/mol.          I need 2.5 kg of a 5 m (moles of solute/kg solvent) solution.

So if I have 25 moles of AlCl3 and add that too 5 kg of water (my solvent)  I get a 5 m solution correct?

Yes, but you will get almost twice more solution than you need.