Question

The boiling point of water at 735 torr is 99.07

c. the mass of nacl added in 100 g water to make its boiling point 100 c is

Answer 1

Boiling point of solution Tb = 100 deg C
Boiling point of water Tbo = 99.07 deg C
Mass of water w1 = 100g =0.1kg
Molar mass of NaCl M2 = 58.5

Using the relation of elevation of boiling point we have

Tb-Tbo = Kb*w2/M2*w1

Kb is the ebuloscopic constant, it s value of different solvent is different, Kb for water = 0.53K kg/mol

Substituting the values and solving for w2,
w2 = (Tb-Tbo)*M2*w1/Kb

w2 = 10.26g