1

Does gas have just two specific heat capacities or more than two? Is the number of specific heat capacities of a gas countable?

view answer >
2

Can we define specific heat capacity at constant temperature?

view answer >
3

Can we define specific heat capacity for an adiabatic process?

view answer >
4

Does a solid also have two kinds of molar heat capacities C_{P} and C_{V}? If yes, do we have C_{P} > C_{V}? Is C_{P} – C_{V} = R?

5

In a real gas the internal energy depends on temperature and also on volume. The energy increases when the gas expands isothermally. Looking into the derivation of C_{P} – C_{V} = R, find whether C_{P} – C_{v} will be more than R, less than R or equal to R for a real gas.

6

Can a process on an ideal gas be both adiabatic and isothermal?

view answer >
7

Show that the slope of p –V diagram is greater for an adiabatic process as compared to an isothermal process.

view answer >
8

Is a slow process always isothermal? Is a quick process always adiabatic?

view answer >
9

Can two states of an ideal gas be connected by an isothermal process as well as an adiabatic process?

view answer >
10

The ratio C_{P}/C_{V} for gas is 1.29. What is the degree of freedom of the molecules of this gas?

1

Work done by a sample of an ideal gas in a process A is double the work done in another process B. The temperature rises through the same amount in the two processes. If C_{A} and C_{B} be the molar heat capacities for the two processes.

2

For a solid with a small expansion coefficient,

view answer >
3

The value of C_{P} – C_{V} is 1.00 R for a gas sample in state A and is 1.08R in state B. Let P_{A}, P_{B} denote the pressures and T_{A,} and T_{B} denote the temperatures of the states A and B respectively. Most likely

4

Let C_{V} and C_{P} denote the molar heat capacities of an ideal gas at constant volume and constant pressure respectively. Which of the following is a universal constant?

5

view answer >

70 calories of heat is required to raise the temperature of 2 moles of an ideal gas at constant pressure from 30°C to 35°C. The amount of heat required to raise the temperature of the same gas through the same range at constant volume is

view answer >

6

view answer >

The molar heat capacity for the process shown in the figure is

view answer >

7

view answer >

The molar heat capacity for the process shown in the figure is

view answer >

8

In an isothermal process on an ideal gas, the pressure increases by 0.5%. The volume decreases by about

view answer >
9

In an adiabatic process on gas with γ = 1.4, the pressure is increased by 0.5%. The volume decreases by about

view answer >
10

Two samples A and B are initially kept in the same state. Sample A is expanded through an adiabatic process and sample B through an isothermal process. The final volumes of the samples are the same. The final pressures in A and B are p_{A} and P_{B} respectively.

11

Let T_{a} and T_{b} be the final temperatures of the samples A and B respectively in the previous question.

12

Let ΔW_{a} and ΔW_{b} be the work done by the systems A and B respectively in the previous question.

13

The molar heat capacity of oxygen gas at STP is nearly 2.5R. As the temperature is increased, it gradually increases and approaches 3.5R. The most appropriate reason for this behaviour is that at high temperatures.

view answer >
1

A gas kept in a container of finite conductivity is suddenly compressed. The process

view answer >
2

Let Q and W denote the amount of heat given to an ideal gas and the work done by it in an isothermal process.

view answer >
3

Let Q and W denote the amount of heat given to an ideal gas and the work done by it in an adiabatic process.

view answer >
4

view answer >

Consider the processes A and B shown in figure. It is possible that

view answer >

5

Three identical adiabatic containers A, B and C contain helium, neon and oxygen respectively at equal pressure. The gases are pushed to half their original volumes.

view answer >
6

A rigid container of negligible heat capacity contains one mole of an ideal gas. The temperature of the gas increases by 1°C it 3.0 cal of heat is added to it. The gas may be

view answer >
7

Four cylinders contain equal number of moles of argon, hydrogen, nitrogen and carbon dioxide at the same temperature. The energy is minimum in

view answer >
1

A vessel containing one mole of a monatomic ideal gas (molecular weight = 20 g mol^{–1}) is moving on a floor at a speed of 50 ms^{–1}. The vessel is stopped suddenly. Assuming that the mechanical energy lost has gone into the internal energy of the gas, find the rise in its temperature.

2

5g of a gas is contained in a rigid container and is heated from 15°C to 25°C. Specific heat capacity of the gas at constant volume is 0.172 cal g^{–1}°C^{–1} and the mechanical equivalent of heat is 4.2 J cal^{–1}. Calculate the change in the internal energy of the gas.

3

view answer >

Figure shows a cylindrical container containing oxygen (γ = 1.4) and closed by a 50 kg frictionless piston. The area of cross section is 100 cm^{2}, atmospheric pressure is 100 kPa and g is 10 ms^{–2}. The cylinder is slowly heated for some time. Find the amount of heat supplied to the gas if the piston moves out through a distance of 20 cm.

view answer >

4

The specific heat capacities of hydrogen at constant volume and at constant pressure are 2.4 cal g^{−1} °C^{−1} and 3.4 cal g^{−1} °C^{−1} respectively. The molecular weight of hydrogen is 2 g mol^{−1} and the gas constant, *R* = 8.3 × 10^{7} erg °C^{−1}mol^{−1}. Calculate the value of *J*

5

view answer >

The ratio of the molar heat capacities of an ideal gas is C_{P}/C_{V} = 7/6. Calculate the change in internal energy of 1.0 mole of the gas when its temperature is raised by 50 K

(a) keeping the pressure constant,

(b) keeping the volume constant and

(c) adiabatically.

view answer >

6

A sample of air weighing 1.18g occupies 1.0 × 10^{3} cm^{3} when kept at 300K and 1.0 × 10^{5} Pa. When 2.0 cal of heat is added to it at constant volume, its temperature increases by 1°C. Calculate the amount of heat needed to increase the temperature of air by 1°C at constant pressure if the mechanical equivalent of heat is 4.2 × 10^{7} erg cal^{–1}. Assume that air behaves as an ideal gas.

7

view answer >

An ideal gas expands from 100 cm^{3} to 200 cm^{3} at a constant pressure of 2.0 × 10^{5} Pa when 50J of heat is supplied to it. Calculate

(a) the change in internal energy of the gas.

(b) the number of moles in the gas if the initial temperature is 300K.

(c) the molar heat capacity C_{P} at constant pressure and

(d) the molar heat capacity C_{V} at constant volume.

view answer >

8

An amount Q of heat is added to a monatomic ideal gas in a process in which the gas performs a work Q/2 on its surrounding. Find the molar heat capacity for the process.

view answer >
9

An ideal gas is taken through a process in which the pressure and the volume are changed according to the equation p = kV. Show that the molar heat capacity of the gas for the process is given by .

view answer >
10

An ideal gas (C_{P}/C_{V} = γ) is taken through a process in which the pressure and the volume vary as p = αV^{b}. Find the value of b for which the specific heat capacity in the process is zero.

11

Two ideal gases have the same value of C_{P}/C_{V} = γ. What will be the value of this ratio for a mixture of the two gases in the ratio 1: 2?

12

A mixture contains 1 mole of helium (C_{P} = 2.5 R, C_{V} = 1.5R) and 1 mole of hydrogen (C_{P} = 3.5 R, C_{V} = 2.5 R). Calculate the values of C_{P}, C_{V} and γ for the mixture.

13

view answer >

Half mole of an ideal gas (γ =5/3) is taken through the cycle abcda as shown in figure. Take .

(a) Find the temperature of the gas in the states a, b, c and d.

(b) Find the amount of heat supplied in the processes ab and bc.

(c) Find the amount of heat liberated in the processes cd and da.

view answer >

14

view answer >

An ideal gas (γ = 1.67) is taken through the process abc shown in figure. The temperature at the point a is 300K. Calculate

(a) the temperature at b and c,

(b) the work done in the process,

(c) the amount of heat supplied in the path ab and in the path bc and

(d) the change in the internal energy of the gas in the process.

view answer >

15

In Joly’s differential steam calorimeter, 3g of an ideal gas is contained in a rigid closed sphere at 20°C. The sphere is heated by steam at 100°C and it is found that an extra 0.095 g of steam has condensed into water as the temperature of the gas becomes constant. Calculate the specific heat capacity of the gas in J g^{–1} K^{–1}. The latent heat of vaporization of water = 540 cal g^{–1}.

16

view answer >

The volume of an ideal gas (γ = 1.5) is changed adiabatically from 4.00 litres to 3.00 litres. Find the ratio of

(a) the final pressure to the initial pressure and

(b) the final temperature to the initial temperature.

view answer >

17

view answer >

An ideal gas at pressure 2.5 × 10^{5} Pa and temperature 300K occupies 100 cc. It is adiabatically compressed to half its original volume. Calculate

(a) the final pressure,

(b) the final temperature and

(c) the work done by the gas in the process. Take γ = 1.5.

view answer >

18

Air (γ = 1.4) is pumped at 2 atm pressure in a motor tyre at 20°C. If the tyre suddenly bursts, what would be the temperature of the air coming out of the tyre. Neglect any mixing with the atmospheric air.

view answer >
19

view answer >

A gas is enclosed in a cylindrical can fitted with a piston. The walls of the can and the piston are adiabatic. The initial pressure, volume and temperature of the gas are 100 kPa, 400 cm^{3} and 300 K respectively. The ratio of the specific heat capacities of the gas is C_{P}/C_{V} = 1.5. Find the pressure and the temperature of the gas if it is

(a) suddenly compressed

(b) slowly compressed to 100 cm^{3}.

view answer >

20

view answer >

The initial pressure and volume of a given mass of a gas (C_{P}/C_{V} = γ) are P_{0} and V_{0}. The gas can exchange heat with the surrounding.

(a) It is slowly compressed to a volume V_{0}/2 and then suddenly compressed to V_{0}/4. Find the final pressure.

(b) If the gas is suddenly compressed form the volume V_{0} to V_{0}/2 and then slowly compressed to V_{0}/4, what will be the final pressure?

view answer >

21

view answer >

Consider a given sample of an ideal gas (C_{P}/C_{V} = γ) having initial pressure P_{0} and volume V_{0}.

(a) The gas is isothermally taken to a pressure P_{0}/2 and from there adiabatically to a pressure P_{0}/4. Find the final volume.

(b) The gas is brought back to its initial state. It is adiabatically taken to a pressure P_{0}/2 and from there isothermally to a pressure P_{0}/4. Find the final volume.

view answer >

22

view answer >

A sample of an ideal gas (γ = 1.5) is compressed adiabatically from a volume of 150 cm^{3} to 50 cm^{3}. The initial pressure and the initial temperature are 150 kPa and 300 K. Find

(a) the number of moles of the gas in the sample,

(b) the molar heat capacity at constant volume,

(c) the final pressure and temperature,

(d) the work done by the gas in the process and

(e) the change in internal energy of the gas.

view answer >

23

Three samples A, B and C of the same gas (γ = 1.5) have equal volumes and temperatures. The volume of each sample is doubled, the process being isothermal for A, adiabatic for B and isobaric for C. If the final pressure is equal for the three samples, find the ratio of the initial pressures.

view answer >
24

Two samples A and B of the same gas have equal volumes and pressures. The gas in sample A is expanded isothermally to double its volume and the gas in B is expanded adiabatically to double its volume. If the work done by the gas is the same for the two cases, show that γ satisfies the equation 1 – 2^{1– γ} = (γ – 1) ln2.

25

view answer >

1 litre of an ideal gas (γ = 1.5) at 300 K is suddenly compressed to half its original volume.

(a) Find the ratio of the final pressure to the initial pressure.

(b) If the original pressure is 100 kPa, find the work done by the gas in the process.

(c) What is the change in internal energy?

(d) What is the final temperature?

(e) The gas is now cooled to 300 K keeping its pressure constant.

Calculate the work done during the process.

(f) The gas is now expanded isothermally to achieve its original volume of 1 litre. Calculate the work done by the gas.

(g) Calculate the total work done in the cycle.

view answer >

26

view answer >

Figure shows a cylindrical tube with adiabatic walls and fitted with an adiabatic separator. The separator can be slid into the tube by an external mechanism. An ideal gas (γ= 1.5) is injected in the two aides at equal pressures and temperatures. The separator remains in equilibrium at the middle. It is now slid to a position where it divides the tube in the ratio 1 : 3. Find the ratio of the temperatures in the two parts of the vessel.

view answer >

27

view answer >

Figure shows two rigid vessels A and B, each of volume 200 cm^{3} containing an ideal gas (C_{V} = 12.5 J K^{–1} mol^{–1}). The vessels are connected to a manometer tube containing mercury. The pressure in both the vessels is 75 cm of mercury and the temperature is 300 K.

(a) Find the number of moles of the gas in each vessel.

(b) 5.0 J of heat is supplied to the gas in the vessel A and 10 J to the gas in the vessel B. Assuming no appreciable transfer of heat from A to B calculate the difference in the heights of mercury in the two sides of the manometer. Gas constant R = 8.3 J K^{–1} mol^{–1}.

view answer >

28

view answer >

Figure shows two vessels with adiabatic walls, one containing 0.1g of helium (γ = 1.67, M = 4 g mol^{–1}) and the other containing some amount of hydrogen (γ= 1.4, M = 2g mol^{–1}). Initially, the temperatures of the two gases are equal. The gases are electrically heated for some time during which equal amounts of heat are given to the two gases. It is found that the temperatures rise through the same amount in the two vessels. Calculate the mass of hydrogen.

view answer >

29

view answer >

Two vessels A and B of equal volume V_{0} are connected by a narrow tube which can be closed by a valve. The vessels are fitted with pistons which can be moved to change the volumes. Initially, the valve is open and the vessels contain an ideal gas (C_{P}/C_{V} = γ) at atmospheric pressure p_{0} and atmospheric temperature T_{0}. The walls of the vessel A are diathermic and those of B are adiabatic. The valve is now closed and the pistons are slowly pulled out to increase the volumes of the vessels to double the original value.

(a) Find the temperatures and pressures in the two vessels.

(b) The valve is now opened for sufficient time so that the gases acquire a common temperature and pressure. Find the new values of the temperature and the pressure.

view answer >

30

view answer >

Figure shows an adiabatic cylindrical tube of volume V_{0} divided in two parts by a frictionless adiabatic separator. Initially, the separator is kept in the middle, an ideal gas at pressure p_{1} and temperature T_{1} is injected into the left part and another ideal gas at pressure p_{2} and temperature T_{2} is injected into the right part. C_{P}/C_{V} = γ is the same for both the gases. The separator is slid slowly and is released at a position where it can stay in equilibrium. Find

(a) the volumes of the two parts,

(b) the heat given to the gas in the left part

(c) the final common pressure of the gases.

view answer >

31

An adiabatic cylindrical tube of cross-sectional area 1 cm^{2} is closed at one end and fitted with a piston at the other end. The tube contains 0.03g of an ideal gas. At 1 atm pressure and at the temperature of the surrounding, the length of the gas column is 40 cm. The piston is suddenly pulled out to double the length of the column. The pressure f the gas falls to 0.355 atm. Find the speed of sound in the gas at atmospheric temperature.

32

The speed of sound in hydrogen at 0°C is 1280 m s^{–1}. The density of hydrogen at STP is 0.089 kg m^{–3}. Calculate the molar heat capacities C_{P} and C_{V} of hydrogen.

33

4.0 g of helium occupies 22400 cm^{3} at STP. The specific heat capacity of helium at constant pressure is 5.0 cal K^{–1} mol^{–1}. Calculate the speed of sound in helium at STP.

34

An ideal gas having density 1.7 × 10^{–3} g cm^{–3} at a pressure 1.5 × 10^{5} Pa is filled in a Kundt tube. When the gas is resonated at a frequency of 3.0 kHz, nodes are formed at a separation of 6.0 cm. Calculate the molar heat capacities C_{P} and C_{V} of the gas.

35

Standing waves of frequency 5.0 kHz are produced in a tube filled with oxygen at 300 K. The separation between the consecutive nodes is 3.3 cm. Calculate the specific heat capacities C_{P} and C_{V} of the gas