Calculate the amount of depression that will occur when 5 g of sodium chloride is dissolved into 0.250 kg of water. remember when sodium chloride dissolves in water it breaks into two particles. the kf for water is 0.512 0c/m.

Answer : The amount of depression will be,

Explanation :  Given,

Mass of sodium chloride = 5 g

Mass of water = 0.250 kg

Molar mass of sodium chloride = 58.5 g/mole

Formula used :  

where,

= change in freezing point

i = Van't Hoff factor for electrolyte solution (sodium chloride) = 2

= freezing point constant =

m = molality

Now put all the given values in this formula, we get

Therefore, the amount of depression will be,

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.