Colligative properties such as freezing point depression were used to find the molar mass of an unknown compound (nowadays we have more advanced instrumentation/techniques). The overall equation is:
Colligative properties such as freezing point depression were used to find the molar mass of an unknown compound (nowadays we have more advanced instrumentation/techniques).
The overall equation is:
∆Tf = mKf
since m = (mol solute)/(kg solvent)
we can write:
∆Tf = [(mol solute)/(kg solvent)]Kf
We can then reorganize the equation to solve for moles of solute:
mol solute = (∆Tf )(kg solvent)/Kf
Since we also know the mass of the solute used, we can plug this in to solve for molar mass:
Molar Mass = grams solute / moles solute
Calculate the molar mass of the solute from the data in the 3rd trial (2nd one with solute added)
(hint: we want think of total grams of solute added and total temperature change)
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