[Azureilai]

Given that at 45 degrees, the solubility of a salt is 72g/100mL water. Find the Molality.

More info:
The above is  based on my lab data, we(my class) are suppose to answer questions on them. The salt is Pottassium Nitrate. This is all the information I have been given. I have a faint idea on how to do the steps but I need confirmation.

I went online to a grams to moles conversion calculator.
http://www.graphpad.com/quickcalcs/moleform.cfm

If I was solving for the problem, do I put 72g for my mass and 101.1032 for the formula? (since 101.1032 is the intermolecular mass of KNO₃) and once I find the moles, is that the answer?

This is my first time doing these types of problems so I don't really know.

[Arkcon]

Well, once you know the moles, you sill have to compute the molality.  You will need the definition of molality, in terms of a formula, to know, what information you still need.

[Azureilai]

Ok, so i found the formula
Molality = mass of solute in gm/molecular mass of solute x mass of solvent in kg

and calculated the mole, which is 712.1436  millimoles. So do I use this formula:

Molality = 712.1436 millimoles / 101.1032 moles * 100mL of water ?

(Just want to make sure my numbers are in the correct place)

[Borek]

mass of solute in gm/molecular mass of solute x mass of solvent in kg

712.1436 millimoles / 101.1032 moles * 100mL of water ?

Compare these two term after term. None is correct - even when the number is correct, you put wrong units.

[Azureilai]

Ok. I will change it. Thanks for pointing that out.