Molality/ Boiling Point Change?

Question

We have to answer this question for some chemistry homework due tonight... I thought I understood it- and I thought I was doing it the right way.. Its below:

What is the boiling point of 0.500 m lactose in water?

I was doing T(delta T/ change)= 1(1.86)(.5)
I got .93, and and then added it to 100 degrees C, and got 100.93. The quiz thingy keeps telling me the answer is wrong. Am I doing anything wrong?

o sorry... the m came out wrong, it was supposed to be italic, for molality.

Answer 1

You are missing the amount of water. The boiling point elevation is based on moles in kg. of solvent. You have the moles, but the amount of water is critical