A vessel of water is put in a dry sealed room of volume 76 m 3 at a temperature of 17 ° C . The S . V . P . of water at 17 ° C is 15 mm of mercury. How much water will evaporate before the water is in equilibrium ? Assume that the vapour obeys perfect gas laws.

Pressure of vapour=15mm of mercury 15 = ρ g h = 15 × 10 - 3 × 9 . 8 × 13600 = 2000 Pa P V = m M R T m = 2000 × 18 × 76 8 . 3 × ( 17 + 273 ) = 1 . 13 5kg

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Unsaturated vapour follows

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Important Questions on Calorimetry and Change of State

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Sometimes white vapour like steam accumulates surrounding a big chunk of ice but no such steam is found around a cup of water. The reason is

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Can air have no dew point? Is it possible for the dew point to go below

0 ° C

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Vapour that remains in contact with its liquid surface within a closed space.

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

What is the saturated vapour pressure of a liquid at normal boiling point?

HARD

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

The temperature of a room is

27 ° C

and relative humidity is

60 %

. Find the fraction of the mass of water vapour contained in the room that will condense, if temperature of the room drops to

10 ° C

SVP

27 ° C 25 ° C

and

10 ° C

are

30 mm, 26.8 mm

and

9 mm

Hg

EASY

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Write the answer:

Why is ice at $0 ° C$ a better cooling agent than water at $0 ° C$ ?

HARD

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

A jar contains a gas and a few drops of water at

T K .

The pressure in the jar is

0.830 m

of mercury. The temperature of the jar is reduced by

1 %

. The saturated vapour pressure of water at the two temperatures are

30 \times 10^{- 3} m

and

25 \times 10^{- 3} m

Hg

. The new pressure in the jar is

MEDIUM

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

The compound with highest boiling point is

HARD

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

The temperature of a room is

27 ° C

and relative humidity is

60 %

. Find the fraction of the mass of water vapour contained in the room that will condense, if temperature of the room drops to

10 ° C

SVP

27 ° C 25 ° C

and

10 ° C

are

30 mm, 26.8 mm

and

9 mm

Hg

MEDIUM

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Mention the differences between a saturated and an unsaturated vapour.

HARD

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

The air at temperature

0 ° C

and having relative humidity

50 %

is taken in a closed glass jar. The temperature of the jar is raised to

20 ° C

. What would be the relative humidity of the air in that jar ? The saturated vapour pressure at

0 ° C

and

20 ° C

are

4.6 mm

and

18 mm

of mercury respectively.

MEDIUM

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

In a closed vessel there is some water mixed with watervapour at

27 ° C

. Total pressure of the mixture is

1.07 \times 10^{6} dyne {cm}^{- 2}

. At this temperature, vapour is just saturated. What will be the pressure in the vessel due to air only at

40 ° C

? What will be the total pressure in the vessel when temperature is reduced to

17 ° C

S . V . P

. at

17 ° C

and

27 ° C

are respectively

1.9 \times 10^{4}

and

3.7 \times 10^{4} dyne {cm}^{- 2}

EASY

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

A beaker of water is kept on a table in the room. Can this water be made to boil by passing steam through it at atmospheric pressure? Give reasons.

MEDIUM

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

A vessel of water is put in a dry sealed room of volume

76 m^{3}

at a temperature of

17 ° C

. The

S . V . P

. of water at

17 ° C

15 mm

of mercury. How much water will evaporate before the water is in equilibrium ? Assume that the vapour obeys perfect gas laws.

HARD

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

What is the condition under which a liquid will have its saturated vapour pressure ?

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

A liquid is boiling in an airtight vessel. Using an exhaust tube, the vapour is slowly removed from the vessel. What will happen to liquid?

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Cotyledons are also called-

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Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Represent the union of two sets by Venn diagram for each of the following.

$X = {x | x$ is a prime number between $80$ and $100}$

$Y = {y | y$ is an odd number between $90$ and $100}$

EASY

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

Draw the melting curves for the different kinds of materials, we find in nature, explaining their differences. Why metling curve does not terminate at a point like the vapourisation curve?

HARD

Physics>Heat and Thermodynamics>Calorimetry and Change of State>Vapour Pressure and Phase Change

The temperature and relative humidity of air in a room are

27 ° C

and

50 %

respectively. Calculate the mass of vapour that should be added to the air in the room to saturate it. Given that volume of the room is

64 m^{3}

and saturated vapour at

27 ° C

3600 Pa

Unsaturated vapour follows

Important Questions on Calorimetry and Change of State

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