A19.12 g mixture of ca(no3)2 and kcl is dissolved in 149 g of water. the freezing point of the solution was measured as −5.77 ∘c . calculate the mass percent of ca(no3)2 in the mixture. a list of values can be found in th

The mass percentage of calcium nitrate is 31.23%.

Explanation:

Let the the mass of calcium nitrate be x and mass of potassium chloride be y.

Total mass of  mixture = 19.12 g

x + y = 19.12 g..(1)

Mass of solvent = 149 g = 0.149 kg

Freezing point of the solution, = -5.77 °C

Molal freezing constant of water = 1.86 °C/m =1.86 °C/(mol/kg)

The van't Hoff factor contribution by calcium nitrate is 3 and by potassium chloride is 2.So:

i = 3

i' = 2

Freezing point of water = T = 0°C

On solving we get:

....(2)

Solving equation (1)(2) for x and y:

x =5.973 g

y = 13.147 g

Mass percent of in the mixture:

The mass percentage of calcium nitrate is 31.23%.