What in the molar mass of a compound if 5.12 grams is dissolved in 25.0 grams of

Question

What in the molar mass of a compound if 5.12 grams is dissolved in 25.0 grams of chloroform solvent to form a solution that has a boiling point of 67.54 degree C? The boiling point of pure chloroform is 61.70 degree C and the boiling point elevation constant, K_yp, is 3.63 degree C/m. a) 29 g/mol b) 32.9 g/mol c) 46.1 g/mol d) 98.9 g/mol e) 127 g/mol Answer e The osmotic pressure of blood is 7.65 aim at 37 degree C. What mass of glucose (C_6H_12O_6), molar mass = 180.2 g/mol) is needed to prepare 2.00 L of solution for intravenous injection? The osmotic pressure of the glucose solution must equal the osmotic pressure of blood. a) 5.04 g b) 52.5 g c) 59.0 g d)108 g e) 908 g Answer. d

Explanation / Answer

2]

delta Tb = 67.54 - 61.7 = 5.84 = i*Kf*m

Kf = 3.63 ; m =molality = moles of solute / Mass of solvent in Kg

5.84 = 5.12*3.63 / 25*10^-3*MW

MW = 127 gms/mol

Answer is e

3]

P = MRT

P - pressure

M = concentration = moles of solute / Volume in L

R - 0.0821 and T in K

7.65 = m*0.0821*[37+273] / 180.2*2

m = 108 gms

answer is d

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