Chemistry Class-11: Chapter –5. States of Matter Part – 6

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Question: 37

Viscosity of a liquid arises due to strong intermolecular forces existing between the molecules. Stronger the intermolecular forces, greater is the viscosity. Name the intermolecular forces existing in the following liquids and arrange them in the increasing order of their viscosities. Also give reason for the assigned order in one line.

Water, hexane , glycerine

Answer:

In water and . Hexane – Dispersion forces/ London forces. The order of viscosities of these liquids is

Hexane has weakest intermolecular forces and glycerine the strongest. (three groups). Therefore, hexane has minimum viscosity and glycerine has maximum viscosity.

Question: 38

Explain the effect of increasing the temperature of a liquid, on intermolecular forces operating between its particles, what will happen to the viscosity of a liquid if its temperature is increased?

Answer:

Question: 39

The variation of pressure with volume of the gas at different temperatures can be graphically represented as shown in Fig. 5.3.

The variation of pressure with volume of the gas

PV Diagram

On the basis of this graph answer the following questions.

(i) How will the volume of a gas change if its pressure is increased at constant temperature?

(ii) At a constant pressure, how will the volume of a gas change if the temperature is increased from ?

Answer:

(1) The volume of a gas will decrease if the pressure on the gas is increased keeping the temperature constant.

(2) On increasing temperature, the volume of a gas will increase if the pressure is kept constant.

Question: 40

Pressure versus volume graph for a real gas and an ideal gas are shown in Fig. 5.4. Answer the following questions on the basis of this graph.

Pressure versus volume graph for a real gas

PV Diagram

(i) Interpret the behaviour of real gas with respect to ideal gas at low pressure.

(ii) Interpret the behaviour of real gas with respect to ideal gas at high pressure.

(iii) Mark the pressure and volume by drawing a line at the point where real gas behaves as an ideal gas.

Answer:

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