Question

what is the boiling point elevation when 147g of lactic acid(C6H10O5)is dissolved in 647g of cyclohexane (C2H12)?the boiling point constant for cyclohexane is 2.79k kg/mol?​

Answer 1

To find:

Boiling point elevation when 147g of lactic acid(C3H6O3) is dissolved in 647g of cyclohexane (C6H12).

Calculation:

Moles of lactic acid :

$= \dfrac{147}{90} = 1.63 \: mol$

Molality of lactic acid in cyclohexane:

$= \dfrac{1.63}{647} \times 1000$

$= \dfrac{1633.3}{647}$

$= 2.52 \: m$

Now , elevation in boiling point :

$\therefore \: \Delta T = i \times k_{f} \times m$

$= > \: \Delta T = 1 \times 2.79 \times 2.52$

$= > \: \Delta T = 7.04 \: K$

So, final answer is:

$\boxed{ \bf{ \: \Delta T = 7.04 \: K }}$

• Van't Hoff Factor will be one (1) because lactic acid is an organic compound and hence does not undergo dissociation.