Ethylene glycol, $\sf\large CO_2H_6O_2 $, is a non-volatile component of a 35% ethylene glycol aqueous solution. The molar mass of ethylene glycol is 62.1 g/mol and the molal freezing-point depression constant for water, $k_f$, is 1.86 $^\circ$C/m (molality).

Question

jamierox4ev3r · Answer

So I know that I'm supposed to use the freezing-point depression equation, which is 

$$\Delta T_f=K_f ~m$$ 

$K_f$ is given in the problem, and m stands for molality. But I'm not exactly sure how to find the molality with this information. So if someone could clear that up for me that would be wonderful. Thanks in advance!

jfraser · Answer

your 35% concentration gives you a way to find molality.

A 35% solution means that, for every 100g of solution, you have 35g of solute, correct?

you don't have to know how much solution you actually $have$, you need to know its concentration, which won't change if you have lots of it or very little of it