A solution is made with 52.0g of an unknown molecular solid with 500.0g of water. Determine the molecular mass of the unkown molecular solid if the frezzingpoint of the solutions is -4.77c

Ok first you must look up the constant for the freezing point depression of water. That constant is 1.86 degrees C /m. You were given 500 g water to do these problems you must change grams into kilograms. 500g x 1Kg/1000g = .5 kg H20

Next we use the formula for freezing point depression ... delta(change) T = i Kf m

m stands for mol

i is 1 for water

Your change was 4.77 C

So I will write it as a formula 4.77 = i (1.86 c/mol) (.5kg H2O) Then multiply 1.86 x .5 = .93

thus.. 4.77C = .93 M lets find how many mols of unknown we have by dividing 4.77/.93 = m you will get 5.13mol

Your Unknown was 52g / 5.13mol = 10.1 g/mol So the answer is 10.1