IX Practical Chemistry KBSE Experiment No. 5

To determine the solubility of Common Salt / Sodium Sulphate / Barium Chloride at Room Temperature.

Viva Voce
Q.1. What is the Chemical name of Common Salt?

Ans. Sodium Chloride.


Q.2. What is the Chemical Formula of Sodium Chloride?

Ans. NaCl.


Q.3. What is Solute?

Ans. The constituent present in larger amount in solution is called Solvent.


Q.4. What is Solvent?

Ans. The constituent present in larger amount in solution is called Solvent.


Q.5. What is Solution?

Ans. The homogeneous mixture of solute and Solvent is called SOlution.


Q.6. What is Solubility?

Ans. The maximum quantity of a solute dissolved in 100 gm. of solvent at a particular

temperature is called the solubility of the solute.


Q.7. What is the name of that substance which dissolve in some other substance?

Ans. It is called Solute.


Q.8. What is the name of that substance which can dissolve other substance?

Ans Any substance which can dissolve a substance to form a homogeneous mixture is called a

Solvent.


Q.9. What is the name of homogeneous mixture of two substances?

Ans. It is called Solution.


Q.10. What is Suturated Solution?

Ans. A solution that can't dissolve any more of the solute at a fixed temperature is called

a Saturated Solution.


Q.11. What are the factors which effect the Solubility?

Ans.

(a) Pressure does not effect the solubility too much in case of a solid and liquid solution.

But the solubility is considerably effected in case of a gas is being dissolved in a liquid.

As the pressure increases at constant temperature more and more gas dissolves.

(b) Solubility of a gas in liquids usually decreases with increase in temperature, owing to

the reason that when we heat the water, the air bubbles come out.

(c) Solubility of Solids usually increases with increase in temperature. Example KNO3 and

KBr.

(d) Those solids that dissolve with liberation of heat usually show decrease in solubility

on increasing the temperature.


Q.12. What is the difference between a Mixture and Solution?

Ans. Mixture A heterogeneous substance in which the constituent can be seen lying side

by side is called a Mixture. Therefore it consists of two or more than two phases.

Solution Homogeneous mixture of two substances is called solution. It is uniform

throughout. Hence it consists of only one phase. In a solution the substances are mixed. So

thoroughly that something new appears to be formed.


Q.13. What is Unsaturated Solution?

Ans. By unsaturated solution we mean that solution in which some more quantity can be

dissolved at that temperature.


Q.14 What is the meaning of Solubility at a particular temperature?

Ans. By solubility at a particular temperature, we mean that quantity of substance (solute)

which is present in 100 gm of solvent at that temperature.


Q.15. What do you mean by Mother Liquor?

Ans. Saturated solution from which the crystals have been removed is called Mother Liquor.


Q.16. How many types of mixture are there?

Ans. There are two types of mixture.

1. Homogeneous Mixture

2. Heterogeneous Mixture


Q.17. Why do you call a solution a Homogeneous Mixture?

Ans Solution is called Homogeneous mixture because it contains one phase only.


Q.18. Why do you heat the solution when the substance is dissolved in the solvent?

Ans. By heating the solubility increases and more substance can be dissolved.


Q.19. What is Evaporation?

Ans. It is the process of change of liquid into vapours at all temperatures.


Q.20 What is the name of that solution in which more of the solute can be dissolved at

the same temperature?

Ans. Unsaturated Solution.


Q.21. What is the formula of Solubility?

Ans. Solubility = Weight of solute / Weight of solvent x 100\


Q.22 What is the difference between Evaporation and Boiling ?

Ans. Evaporation Evaporation takes place on the surface of liquid and at all the

temperature.

Boiling Boiling takes place at a fixed temperature and throughout the liquid.


Q.23. What is the Boiling Point of water at Sea Level?

Ans. The Boiling Point of water at Sea Level is 100oC.


Q.24. What is the relation between Boiling Point and Vapour Pressure?

Ans. Temperature at which vapour pressure of liquid becomes equal to atmospheric pressure is

called Boiling Point.


Q.25. What do you understand by Boiling Point?

Ans. That fixed temperature at which the liquid changes into vapour or the vapour pressure

becomes equals to atmospheric pressure is called Boiling Point.


Q.26. Why is it so that sugar is insoluble in Petrol?

Ans. A solution is not formed if the attractive forces between the components of solute are

greater than attractive forces between the solute and solvent.


Q.27. When is it easier to form a solution?

Ans. It is easier to form a solution if attractive forces in components of solute are less

than the attractive forces between the solute and the solvent.


Q.28. What are Isomorporhous Mixture?

Ans. Solid solutions are sometimes called Isomorphous Mixtures because the constituents of

such solution can be separated on Crystallisation.


Q.29. How many classes of Solution are there?

Ans.

1. Gas in gas

2. Gas in liquid

3. Gas in solid

4. Liquid in gas

5. Liquid in liquid

6. Solid in liquid

7. Liquid in solid

8. Solid in solid


Q.30. Give an example of Gas in Gas

Ans. Air


Q.31. Give an example of solution of liquid in gas?

Ans. Water vapour in air.


Q.32. Give an example of solution of solid in gas?

Ans. Iodine in Nitrogen Gas.


Q.33. Give an example of solution of gas in liquid?

Ans. Oxygen or Carbon Dioxide in Water.


Q.34. Give an example of solution of liquid in liquid?

Ans. Alcohal in water or Bromine in Carbon Disulphate.


Q.35. Give an example of solution of solid in liquid?

Ans. Salt in water, Sugar in water.


Q.36. Give an example of Gas in Solid?

Ans. Hydrogen in Pladium.


Q.37. Give an example of solution of liquids in solids?

Ans. Mercury in Sodium.


Q.38. Give an example of solution of solid in solid?

Ans. Alloys like Brass and Bronze.


Q.39. What are the main precautions in this experiment?

Ans. The following precautions should be kept into consideration.

1. Physical Balance should be adjusted before the start of practical.

2. Weights should be placed on the right hand pan.

3. During determination of weight the shutter should remain closed.

4. The mass of the China Dish should be determined after cooling.


Q.40. Which kind of lever is the Physical Balance?

Ans. First kind of Lever.


Q.41. Which is heavier 20 gm of Iron or 20 gm of Cotton?

Ans. Both will have the same weight.


Q.42. What do you understand by the beam of a Physical Balance?

Ans. The beam is a horizontal metal frame work capable of turning freely with very little

friction about an "Agate Knife Edges"at its centre called Fulcrum.


Q.43. How many knife edges are there in the Physical Balance?

Ans. There are three knife edges. One at the middle and two at the end.


Q.44. What are the important parts of Physical Balance?

Ans. The important part of Physical Balance are given below.

1. Beam

2. Adjusting Screws

3. Knife Edge

4. Stump

5. Pan

6. Vertical Pillar, Pointer Scale

7. Plumb Line (or Spirit Level)

8. Levelling Screws

9. Knob.


Q.45. What is the purpose of the Plumb Line?

Ans. To make the pillar vertical and base horizontal.


Q.46. What should be done if the plumb line is broken?

Ans. In such case spirit level is used to test the level of the base of the Physical

Balance.


Q.47. Why is it advised that when Balance is not in use should not be raised too much?

Ans. The sharpness of the knife edge is preserved.


Q.48. Why do we place the Physical Balance in a glass case?

Ans. It is kept in a glass case to prevent it from being disturbed by wind when weighing is

going on and from being contaminated with acid fumes and moisture.


Q.49. What are the conditions to be satisfied by a good balance?

Ans. A good balance must satisfy the following conditions.


Q.50. What are Fractional Weights?

Ans. Milligram weights which are made up of heavy aluminium or then platinum foils are known

as "Fractional Weights".


Q.51. On the Specific Gravity, 25 ml, 50 ml and 20oC is written. What do you mean by

that?

Ans. 25 ml and 50 ml means 25 millilitre, 50 millilitre which indicates the volume of the

bottle. 20oC is the temperature at which the volume of the particular bottle is 25 ml or 50

ml.


Q.52. What is Physical Balance?

Ans. It is the instrument for comparing the mass of an object with a known mass.


Q.53. What is the Principal of Balance?

Ans. It works on the Principles of First Kind of Lever.


Q.54. Convert 865 mg in gram.

Ans. 865 mg = .865 gm.


Q.55.How many milligrams are there in one gram?

Ans. 1000 mg = 1 gm.


Q.56. How many ml are there in one litre/

Ans. 1000 ml = 1 litre.


Q,57. What is the effect of temperature on the solubility of substance?

Ans. The solubility of a substance increases by increase of temperature.


Q.58. What is the effect of pressure on the boiling point of a liquid?

Ans. Boiling Point is lowered when the pressure is decreased and it is increased when the pressure is raised.


Q.59. At what temperature will the water if the pressure is reduced from 760 mm to 24 mm of Hg?

Ans. The water boils at 25oC if the pressure is reduced from 760 mm to 24 mm of Hg.