# Internal Energy

## Trending Questions

**Q.**The internal energy (U) of an ideal gas is plotted against volume for a cyclic process ABCDA, as shown in the figure.

The temperature of the gas at B and C are 500 K and 300 K, respectively. The heat absorbed by the gas (in cal/mol) in this cyclic process, is :

**Q.**

Define Quantisation of energy.

**Q.**One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperatures at A, B and C are 400 K, 800 K and 600 K respectively. Choose the correct statement:

- The change in internal energy in the process AB is -350 R.
- The change in internal energy in whole cyclic process is 250 R.
- The change in internal energy in the process BC is -500 R.
- The change in internal energy in the process CA is 700 R.

**Q.**The maximum efficiency of a heat engine operating between 100oC and 25oC is

- 20.11%
- 22.2%
- 25.17%
- None

**Q.**The standard enthalpies of formation of Al2O3 and CaO are −1675 kJmol−1 and −635 kJ mol−1 respectively.

For the reaction,

3CaO+2Al→3Ca+Al2O3 the standard reaction enthalpy, ΔrH0=______kJ (Rounded off to the Nearest Integer).

**Q.**1 gram sample of NH4NO3 is decomposed in a bomb calorimeter. The temperature of the calorimeter increases by 6.12 K. The heat capacity of the system is 1.23 kJ/g-deg. What is the molar heat of decomposition for NH4NO3?

- 7.53 kJ/mol
- −398.1 kJ/mol
- −16.1 kJ/mol
- 602 kJ/mol

**Q.**When 1 moe of ice melts at 0oC and at constant pressure of 1 atm, 1440 calories of heat are absorbed by the system. The molar volume of ice and water are 0.0196 and 0.0180 litre respectively. Which of the following is correct?

- ΔU≈ΔH
- ΔU=1548 cal
- ΔU=1056 cal
- None of the above

**Q.**If 500 calorie of heat energy is added to a system and the system does 350 calorie of work on the surroundings, the energy change of the system is:

- -150 cal
- 850 cal
- -850 cal
- 150 cal

**Q.**

One litre of a mixture of carbon monoxide and carbon dioxide is passed through a tube containing red hot charcoal , the volume now becomes 1.6 litres. Volumes are measured under similar conditions. Find out the composition of gaseous mixture.

**Q.**

A sample of ideal gas (γ = 1.4) is heated at constant pressure. If 140 J of heat is supplied to gas, find ΔU and w.

60 J, -80 J

-50 J, 60 J

None of these

50 J, -60 J

**Q.**Express the rate for the following reaction in terms of concentration of reactants and products.

H2(g)+I2(g)→2HI(g).

**Q.**Two mole of ideal diatomic gas (Cv, m=5/2 R) at 300 K and 10 atm expanded irreversibly and adiabatically to a final pressure of 2 atm against a constant pressure of 1 atm. Calculate change in internal energy △U

- −2164.1 J
- −1052.1 J
- −1662.8 J
- 864.28J

**Q.**A gas occupies 2 litre at STP. It is provided with 58.63 J of heat so that its volume becomes 2.5 litre at 1 atm. Calculate the change in its internal energy (in J).

- 8.6
- 10
- 15.8
- 11.5

**Q.**According to the following figure, the magnitude of the enthalpy change of the reaction

A+B→M+N in kJ mol1

is equal to . (Integer answer)

**Q.**

A gas at $50\xc2\xb0\mathrm{C}$ constant pressure and a constant pressure requires the heat $160\mathrm{calories}$ to raise the temperature. The same mass of gas requires $100\xc2\xb0\mathrm{C}$ a constant volume and $240\mathrm{calories}$ heat is released. Degrees of freedom does each molecule of this gas have? (Assume that gas is ideal)

$7$

$5$

$6$

$3$

**Q.**The standard enthalpies of formation at 300 K for CCl4(l), H2O (g), CO2(g) and HCl(g) are −107, −242, −394 and−93 kJ mol−1, respectively. The value of △Uo300 for the reaction:

CCl4(l)+2H2O(g)→CO2(g)+4HCl(g) is

−x kJ mol−1. Find the value of x

(Take R=8.314 JK−1mol−1)

**Q.**Two moles of an ideal monoatomic gas occupies a volume V at 27 ∘C. The gas expands adiabatically to a volume 2V. Calculate (a) the final temperature of the gas and (b) change in its internal energy.

- (a) 189 K (b) 2.7 kJ
- (a) 295 K (b) - 2.7 kJ
- (a) 189 K (b) -2.7 kJ
- (a) 295 K (b) 2.7 kJ

**Q.**

The internal energy change when a ssyste goes from state A TO B is 40kJ/mol.If the system goes from A to by a reversible path and returns to state A by an irreversible path what would be the change in internal energy

**Q.**

An electric heater supplies heat to a system at a rate of 100W. If system performs work at a rate of 75 joules per second. At what rate is the internal energy increasing?

**Q.**

Does entropy increase in an open system?

**Q.**The value of ΔH−ΔU for the following reaction at 37o C will be

2NH3(g)→N2(g)+3H2(g)

- 51.54 J mol−1
- −51.54 J mol−1
- 51.54 kJ mol−1
- 5.154 kJ mol−1

**Q.**A gas sample is cooled and loses 65 J of heat. The gas contracts as it cools and work done on the system equal to 20 J. What are q, w and △U ?

- q=−65 J, w=20 J, △U=−45 J
- q=−70 J, w=10 J, △U=35 J
- q=65 J, w=10 J, △U=−35 J
- q=65 J, w=20 J, △U=45 J

**Q.**If the ratio of specific heat of a gas at constant pressure to that at constant volume is γ, the change in internal energy of a mass of gas, when the volume changes from V to 3V under constant pressure P, is

- R(γ−1)
- PV
- γPVγ−1
- 2PVγ−1

**Q.**A system is changed from state A to state B by one path and from B to A by another path. If △U1 and △U2 are the corresponding changes in internal energy, then:-

- △U1+U2=+ve
- △U1+U2=−ve
- △U1+U2=0
- None of the above

**Q.**The internal energy of an ideal gas:

- increases with increase in temperature
- remains unaffected with temperature
- decreases with increase in temperature
- can be calculated by the reaction, E=mc2

**Q.**

Which of the following statements is correct for the reaction CO(g) + 12 O2(g) → CO2(g) at constant temperature and pressure?

None of these

**Q.**Internal energy is an example of

- None of these
- Path function
- State function
- Both (a) and (b)

**Q.**One gram of ice (at 0oC) is mixed with one gram of steam (at 100oC). After thermal equilibrium, the temperature of the mixture is

- 0oC
- 100oC
- 55oC
- 80oC

**Q.**

Is entropy a function of time?

**Q.**When an iron rod is heated in a furnace, the colour of the iron rod first turns dull red and on further increase in temperature it changes to bright red to orange, then yellow, progressively white and then finally blue at the elevated temperatures.

This sequence of colours observed on heating an iron rod are in the sequence of __________

- Increasing wavelength
- Decreasing wavelength
- Decreasing frequency
- None of the above