IS MATTER AROUND US PURE part 3

3. To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293 K. Find its concentration at this temperature.
Mass of solute = 36g
Mass of solvent = 100g
Mass of solution = Mass of solute + Mass of solvent
= 36g + 100g
= 136g
Concentration = Mass of solute/Mass of solution * 100%
= 36/136 * 100%
= 26.5%
Questions (pg 24)
1. How will you separate a mixture containing kerosene and petrol (difference in their boiling points is more than 25OC), which are miscible with each other.
(i) Take the mixture in a distillation flask and fit it with a thermometer.
(ii) Place a condenser outlet below and connect it to the distillation flask by using a water condenser.
(iii) Heat the mixture slowly by keeping a close watch at the thermometer.
(iv) The petrol vaporises, condenses in the water condenser and can be collected frm the condenser outlet.
(v) Kerosene is left behind in the distillation flask.

2. Name the technique to separate:
(i) butter from curd: centrifugation
(ii) salt from sea-water: evaporation
(iii) camphor from salt: sublimation

3. What type of mixtures are separated by the technique of crystallisation?
The mixtures whose components have different solubilities in water are separated by crystallisation.