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

Answer 1

\[MgCl _{2} --> Mg ^{+} + 2Cl ^{-}\]

one mole of Magnesium ions
2 moles of chlorine ions.

1+2 = 3 moles of ions

i = 3.

m = molality moles/kg solvent. 2

\[iK _{b} \Delta T \]

\[3*0.5\frac{ C}{ m }*2m = 3C = \Delta T \]

Answer 2

\[\Delta T = t _{f}-t _{i} \]

boiling point is 100C so we know that the boiling point had to have been raised over that by some amount.

\[\Delta T + Ti = Tf \]

\[3C + 100 = 103 C\]