Question

What is the approximate molar mass of a molecular solute if 30 g of the solute in 100 g of

water causes the solution to have a boiling point of 101°C? (Kb=0.512°C/m: Kf=1.86 °C/m;

molar mass of water =18 g)

15 amu

300 amu

150 amu

30 amu

Answer 1

@Cuanchi

Answer 2

@aaronq

Answer 3

@nincompoop

Answer 4

Do you have any idea on how to use the information given to figure it out?

Answer 5

not really

Answer 6

You have to use the boiling point elevation equation, find the molality, then find the moles of solute, then finally (knowing it's mass) find the molar mass.

Solve for m, molality: \(\sf \Delta T=m*K_b\)

Solve for n, moles: \(\sf m=\dfrac{n}{Kg_{solvent}}\)

Solve for molar mass: \(\sf n=\dfrac{mass}{Molar~mass}\)

Answer 7

so how would i figure it out @aaronq

Answer 8

i kinda already broke it down for you, solve for each one of the variables in the equations i wrote.

Answer 9

15 @aaronq

Answer 10

hm that's not correct, can you briefly post your calculations?

Answer 11

then 150?

Answer 12

@aaronq

Answer 13

yup