Homework Help: college chemistry

Posted by Anonymous on Thursday, February 3, 2011 at 9:08pm.

A 1.875 g sample of pyrazine was dissolved in 25.00g of water, producing a solution that freezes at -1.55 C. Assume the solution behaves ideally. Kf(H2O)=1.86 C/molality.
What is the experimental molecular weight of pyrazine?

college chemistry - DrBob222, Friday, February 4, 2011 at 12:27pm
delta T = Kf*molality
Solve for molality

molality = moles/kg solvent
Solve for moles

moles = grams/molecular weight
Solve for molecular weight.

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