Chemistry Help?

Question

Suppose substance X has molar mass 50.0 g/mol. How many grams of substance X would you need to add to 4.79 kg of water to lower the freezing point to -1.30 C?

Answer 1

Step 1:

Freezing point of the water .

Molar Mass of the substance is 50.0 g/mol.

Amount of water is 4.79 kg.

Let mass of the substance be grams.

Freezing point of water , where

is the change in temperature and .

is the van't Hoff factor, assume .

is the molality of the solution

Molality of the compound dissolved is .

is the molality depression constant = .

Freezing point :

Step 2:

Amount of sucrose in grams is

m(grams) = Molar mass of substance(g/mol) * amount of substance (mol)

Mass of the substance in grams is 167.45 grams.

Solution:

Mass of the substance in grams is 167.45 grams.