.........g CH4O -WITH STEPS PLEASE-

Question

Find how many grams of (nonelectrolyte) CH₄O would have to be added to 1000 g of H2O to produce a solution with a freezing point of -3.65 °C?

.........g CH4O

Answer 1

Freezing point depression:

∆T = imK

∆T = change in temperature = 3.65ª

i = van't Hoff factor = 1 for a non electrolyte

m = molal = moles solute / kg solvent = ?

K = freezing constant for water = 1.86º/m

Solving for m, we have..

m = ∆T / (i)(K) = 3.65º / 1.86º/m

m = 1.96 moles/kg

Since we have 1000 g, that is 1 kg of solvent. So, we must then have 1.96 moles of solute, CH4O.

Grams CH4O = 1.96 moles CH4O x 32 g/mol = 62.8 g CH4O