A metal, M , of atomic mass 56 amu reacts with chlorine to form a salt that can be represented as MClx.

Question

A boiling point elevation experiment is performed to determine the subscript 𝑥 , and therefore, the formula of the salt. A 39.0 g sample of the salt is dissolved in 100.0 g of water and the boiling point of the solution is found to be 377.88 K. Find the formula of the salt. Assume complete dissociation of the salt in solution.

Answer 1

You asked this question about a week ago, and I provided an answer at that time. If you didn't understand my answer, or if you found a problem with it, it would help us both if you would comment instead of posting the same question again. Since you didn't, I'll repeat my answer here and maybe you will provide feeback.

molar mass of unknown = 56 + 35x (since atomic mass Cl = 35)

For the colligative property boiling point elevation, the equation that is used is...

∆T = imK

K = contant = 0.512

∆T = change in boiling point = 377.88K - 373.15K = 4.73º

i = van't Hoff factor = 1 + x (1 for M and x for Cl)

m = molality = moles solute/kg solvent = [39 g/(56 + 35x (0.512) ] ÷ 0.1 kg

This then becomes a math problem, so good luck. Plug in the above information into ∆T = imK and solve for x which should be the number or Cl present in MCl_x