09 Thermodynamics and Thermochemistry Quiz | Chemistry Quiz
In this Chemistry quiz article, we are going to share some Chemistry study material and some multiple-choice questions of solution chapter which having some topics like First law of thermodynamics and Hess law, IInd & IIIrd Law of thermodynamics and Entropy, Heat of reaction, Bond energy, Free energy, and Work function.Thermodynamics
Thermodynamics (Greek word thermo means heat and dynamics means motion) is the branch of science which deals with the study of different forms of energy and the quantitative relationships between them.The complete study of thermodynamics is based upon three generalizations called first, the second and third law of thermodynamics. These laws have arrived purely on the basis of human experience and there is no theoretical proof for any of these laws.
Basic concepts
(1) System, surroundings, and Boundary: A specified part of the universe that is under observation is called the system and the remaining portion of the universe which is not a part of the system is called the surroundings.The system and the surroundings are separated by real or imaginary boundaries. The boundary also defines the limits of the system. The system and the surroundings can interact across the boundary.
(2) Types of systems
(i) Isolated system: This type of system has no interaction with its surroundings. The boundary is sealed and insulated. Neither matter nor energy can be exchanged with the surrounding. A substance contained in an ideal thermos flask is an example of an isolated system.(ii) Closed system: This type of system can exchange energy in the form of heat, work or radiations but not matter with its surroundings. The boundary between the system and surroundings is sealed but not insulated. For example, liquid in contact with vapor in a sealed tube and pressure cooker.
(iii) Open system: This type of system can exchange matter as well as energy with its surroundings. The boundary is neither sealed nor insulated. Sodium reacting with water in an open beaker is an example of an open system.
Basic concepts Quiz
1. The heat produced in calories by the combustion of one gram of carbon is called(a) Heat of combustion of carbon
(b) Heat of formation of carbon
(c) Calorific value of carbon
(d) Heat of production of carbon
Sol: (c) It is the definition of calorific value.
2. The temperature of the system decreases in an
(a) Adiabatic compression
(b) Isothermal compression
(c) Isothermal expansion
(d) Adiabatic expansion
Sol: (d) When a real gas is forced through a porous plug into a region of low pressure, it is found that due to expansion, the gas on the side of low pressure gets cooled.
The phenomenon of producing lowering of temperature when a gas is made to expand adiabatically from a region of high pressure into a region of low pressure is known as Joule-Thomson effect.
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3. Which of the following is zero for an isochoric process
(a) dp (b) dV
(c) dT (d) dE
Sol: (b) dV=0 for an isochoric process.
4. For the isothermal expansion of an ideal gas
(a) E and H increases
(b) E increases but H decreases
(c) H increases but E decreases
(d) E and H are unaltered
Sol: (d) In isothermal reversible process ideal gas has constant volume
5. If a refrigerator's door is opened, then we get
(a) Room heated
(b) Room cooled
(c) More amount of heat is passed out
(d) No effect on room
Sol: (a) The compressor has to run for longer time releasing more heat to the surroundings.
6. In an isochoric process the increase in internal energy is
(a) Equal to the heat absorbed
(b) Equal to the heat evolved
(c) Equal to the work done
(d) Equal to the sum of the heat absorbed and work done
Sol: (a)
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7. It is general principle that the less energy a system contains, it is
(a) Less stable (b) More stable
(c) Unstable (d) More unstable
Sol: (b) The less energy of a system and more is its stability.
8. Internal energy is an example of
(a) Path function (b) State function
(c) Both (a) and (b) (d) None of these
Sol: (b) The functions whose value depends only on the state of a system are known as state functions.
First law of thermodynamics and Hess law Quiz
9. The law of Lavoisier and Laplace illustrates
(a) The principle of conservation of energy
(b) Equivalence of mechanical and thermal energy
(c) The principle of conservation of matter
(d) Equivalence of mechanical and chemical energy
Sol: A
10. During an isothermal expansion of an ideal gas its
(a) Internal energy increases
(b) Enthalpy decreases
(c) Enthalpy remains unaffected
(d) Enthalpy reduces to zero
Sol: (c) During isothermal expansion of ideal gas,
11. The law of conservation of energy states that
(a) The internal energy of a system is constant
(b) The heat content of a system is constant
(c) Energy is neither created nor destroyed
(d) There is an equivalence between energy and mass
Sol: C
12. The enthalpies of the elements in their standard states are assumed to be
(a) Zero at 298 K
(b) Unit at 298 K
(c) Zero at all temperatures
(d) Zero at 273 K
Sol: (a)The enthalpies of all elements in their standard state at 25C or 298K are zero.
13. An ideal gas at constant temperature and pressure expands, then its
(a) Internal energy remains same
(b) Internal energy decreases
(c) Internal energy increases
(d) Entropy first increases and then decreases
Sol: (a) At constant T and P internal energy of ideal gas remains unaffected.
14. The internal energy of a substance
(a) Increases with increase in temperature
(b) Decreases with increase in temperature
(c) Can be calculated by the relation E=MC2
(d) Remains unaffected with change in temperature
Sol: (a) Del(E) increases with temperature.
15. Joule-Thomson expansion is
(a) Isobaric
(b) Isoenthalpic
(c) Isothermal
(d) None of these
Sol: (b) Joule-Thomson expansion is isoenthalpic.
IInd & IIIrd Law of thermodynamics and Entropy Quiz
16. Which of the following is the least random state of water
(a) Ice
(b) Liquid water
(c) Steam
(d) All present same random state
Sol: A
17. The entropy of crystalline substances at absolute zero going by the third law of thermodynamics should be taken as
(a) 100
(b) 50
(c) Zero
(d) Different for different substances
Sol: (c) It is the third law of thermodynamics.
18. In which state, the matter have highest entropy
(a) Solid (b) Liquid
(c) Gas (d) Equal in all
Sol: (c) Entropy of gases is highest.
19. Which of the following statement is true. The entropy of the universe
(a) Increases and tends towards maximum value
(b) Decreases and tends to be zero
(c) Remains constant
(d) Decreases and increases with a periodic rate
Sol: A
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20. The total entropy change for a system and its surroundings increases, if the process is
(a) Reversible (b) Irreversible
(c) Exothermic (d) Endothermic
Sol: (d) For endothermic process Del(S) increases.
21. The entropy of a perfectly crystalline solid at absolute zero is
(a) Positive (b) Negative
(c) Zero (d) Not definite
Sol: (c) According to III law of thermodynamics.
22. Maximum entropy will be in which of the following
(a) Ice (b) Liquid water
(c) Snow (d) Water vapours
Sol: (d) Entropy is the measure of randomness in the molecules. Randomness is maximum in case of gases. Hence, entropy is maximum for water vapours.
Heat of reaction Quiz
23. The enthalpy of fusion of ice per mole(a) 18 kJ (b) 8 kJ
(c) 80 kJ (d) 6 kJ
Sol: d
24. An exothermic reaction is one which
(a) Takes place only on heating
(b) Is accompanied by a flame
(c) Is accompanied by a absorption of heat
(d) Is accompanied by evolution of heat
Sol: (d) In exothermic reactions heat is evolute.
25. An endothermic reaction is one in which
(a) Heat is converted into electricity
(b) Heat is absorbed
(c) Heat is evolved
(d) Heat is converted into mechanical work
Sol: b
26. Heat of combustion of a substance
(a) Is always positive
(b) Is always negative
(c) Is equal to heat of formation
(d) Nothing can be said without reaction
Sol: B
27. Which of the following fuels will have the highest calorific value (kJ/kg)
(a) Charcoal (b) Kerosene
(c) Wood (d) Dung
Sol: (b) Out of given substances, kerosene oil has maximum calorific value.
Bond energy Quiz
28. The bond dissociation energy needed to form benzyl radical from toluene is ..... than the formation of the methyl radical from methane(a) Less
(b) Much
(c) Equal
(d) None of the above
Sol: A
29. If enthalpies of methane and ethane are respectively 320 and 360 calories then the bond energy of C-C bond is
(a) 80 calories (b) 40 calories
(c) 60 calories (d) 120 calories
Sol: (b) .
Free energy and Work function Quiz
30. A minus sign of the free energy change denotes that
(a) The reaction tends to proceed spontaneously
(b) The reaction is non-spontaneous
(c) The system is in equilibrium
(d) The reaction is very much unlikely
Sol: (a)When than the reaction is spontaneous in nature.
31. Spontaneity of a chemical reaction is decided by the negative change in
(a) Internal energy (b) Enthalpy
(c) Entropy (d) Free energy
Sol: (d)
32. Born-Haber cycle is used to determine
(a) Crystal energy (b) Electron affinity
(c) Lattice energy (d) All of these
Sol: d
33. For a spontaneous change, free energy change Del(G) is
(a) Positive
(b) Negative
(c) Zero
(d) Can be positive or negative
Sol: (b) For spontaneous change Del(G) = -ve.
34. In which of the following entropy decreases ?
(a) Crystallization of sucrose from solution
(b) Rusting of iron
(c) Melting of ice
(d) Vaporization of camphor
Sol: (a) Because randomness is decreases.
35. In endothermic reaction, the value of change in enthalpy Del(H) is
(a) Positive
(b) Negative
(c) Zero
(d) None of these
Sol: (a)
36. Heat of reaction at constant volume is measured in the apparatus
(a) Bomb calorimeter (b) Calorimeter
(c) Pyknometer (d) Pyrometer
Sol (a) Bomb calorimeter is used to measure heat of reaction.
37. Which of the following gas has the highest heat of combustion
(a) Methane (b) Ethane
(c) Ethylene (d) Acetylene
Sol: (b) Larger the number of C and H atoms, greater is the heat of combustion.
