If the boiling point constant of water is 0.5 C/m what is the approximate boiling point of 2m solution of magnesium chloride?

Answers in Celsius
101.5
98.5
97.0
103.0

Question

If the boiling point constant of water is 0.5 C/m what is the approximate boiling point of 2m solution of magnesium chloride?

Answers in Celsius 
101.5 
98.5
97.0
103.0

photon336 · Answer

$$MgCl _{2} --> Mg ^{+} + 2Cl ^{-}$$

one mole of Magnesium ions 
2 moles of chlorine ions.

1+2 = 3 moles of ions 

i = 3. 

m = molality moles/kg solvent. 2 

$$iK _{b} \Delta T $$ 

$$3*0.5\frac{ C}{ m }*2m = 3C = \Delta T $$

photon336 · Answer

$$\Delta T = t _{f}-t _{i}  $$

boiling point is 100C so we know that the boiling point had to have been raised over that by some amount. 

$$\Delta T + Ti = Tf $$

$$3C + 100 = 103 C$$