Q28 of 40 Page 2

Which separation technique will you apply for the separation of the following?

(a) Sodium chloride from its solution in water


(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride


(c) Small pieces of metal in the engine oil of a car.


(d) Different pigments from an extract of flower petals.


(e) Butter from curd.


(f) Oil from water.


(g) Tea leaves from tea.


(h) Iron pins from sand.


(i) Wheat grains from husk.


(j) Fine mud particles suspended in water.

(a) Sodium chloride can be separated from its solution in water by the process of Evaporation. This solution is boiled or evaporated. After evaporation sodium chloride will be left behind.

(b) Ammonium chloride can be separated from a mixture containing sodium chloride and ammonium chloride by the process of ‘Sublimation’. On heating this mixture, ammonium chloride changes directly from solid to gaseous state leaving behind sodium chloride. During this process, the solids form of ammonium chloride can be collected on the sides of the funnel.


(c) Small pieces of metal in the engine oil of a car can be separated by the process of ‘Filtration’.


(d) Different pigments from an extract of flower petals can be separated by the process of ‘Chromatography’. Chromatography is the technique which is used for separation of those solutes that dissolve in the same solvent.


(e) Butter can be separated from curd by the process of Centrifugation. The principle behind this process is that the denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.


(f) Oil can be separated from water by using ‘Separating funnel’. Mixture of oil and water are poured in the funnel and are allowed to stand undisturbed for sometime. This results in the formation of separate layers of water and oil.


(g) Tea leaves from tea can be separated by filtration.


(h) Iron pins can be separated from sand by using a magnet.


(i) Wheat grains can be separated from husk by Winnowing. It is a very simple process in which the wheat grains are thrown into the air, so that the wind blows away the lighter husk.


(j) Mud particles suspended in water can be removed by decantation and filtration.

More from this chapter

All 40 →
26

Draw a labelled diagram showing the process of fractional distillation.

 27

Pragya tested the solubility of four different substances at different temperatures and collected the data as given below (results are given in the following table as grams of substance dissolved in 100 grams of water to form a saturated solution).


(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?


(b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.


(c) Find the solubility - of each salt at 293 K. Which salt has the highest solubility at this temperature?


(d) What is the effect of change in temperature on the solubility of a salt?

 29

There are three substances X, Y and Z. The substance X does not have a fixed melting point or boiling point and it still shows the individual properties of its constituents. The substance Y is a pure substance which occurs in nature as such. The substance Y has a fixed melting point and boiling point but it cannot be broken down into simpler substances by any chemical means. The substance Z is also a pure substance whose properties are entirely different from those of its constituents. The substance Z can, however, be divided by electrolysis into two substances which belong to the same class of substances as Y.

(a) What type of substance could X be? Name one substance like X.


(b) What type of substance could Y be? Name one substance like Y.


(c) What type of substance could Z be? Name one substance like Z.


(d) Which process involves absorption or release of an appreciable amount of energy: formation of substance X or formation of substance Z?


(e) Name the three groups into which all the substances like Y are divided on the basis of their properties.

 30

There is a large group of materials P which can be divided into three groups Q, R, and S on

the basis of their properties. The substances belonging to group Q can be solids, liquids or gases. The solids belonging to group Q are usually electrical insulators. Most of the substances of group R are solids which are good conductors of electricity. The substances belonging to group S are neither insulators like Q nor good conductors like R. The properties of S are intermediate between those of Q and R.


(a) What could the group of materials P be?


(b) Name the substances Q. Give two examples of such substances.


(c) Name the substances R. Write two examples of such substances.


(d) Name the substances S. Give two examples of such substances.


(e) Out of Q, R and S, which substances are malleable and ductile?