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| Chemistry 11th Chapter 7 Thermochemistry Questions Bank |
Chemistry 1st Year Chapter 7 Thermochemistry Questions Bank
MCQs
Please select the right answer.
1. A hypothetical reaction X → 2Yproceeds by the following sequence of steps: 1/2X → Z ∆H = q1 Z → 2W ∆H = q2 W → 1/2Y ∆H = q3 The values for the ∆H of the reaction is:
2. A state function which describes together the internal energy and product of pressure and volume is called_______.
3. According to Hess’s Law, the enthalpy change for a reaction:
4. An isothermal process is one in which:
5. At constant pressure, heat of reaction is represented by:
6. At constant volume, heat of reaction is represented by:
7. Calorie is equivalent to:
8. Calories are equivalent to:
9. Change in enthalpy of ∆H a system can be calculated by the following relationship:
10. Choose from the following the correct statement about Born Harbor cycle:
11. Decomposition of H₂O is:
12. During an exothermic or endothermic reaction which one of the following formulae is used to calculate the amount of heat evolved or absorbed_____.
13. Enthalpy of formation of one mole of an ionic compound from gaseous ion under standard condition is called______.
14. Enthalpy of neutralization of strong acids and strong bases have the same values because:
15. First law of thermodynamics is represented as:
16. For an endothermic reaction, enthalpy of reactants:
17. Hess’s law is analogous to:
18. If an endothermic reaction is allowed to take place very rapidly in air, the temperature of the surrounding air will?
19. If an exothermic reaction is allowed to take place very rapidly in air, the temperature of surrounding air:
20. In an exothermic reaction AR is:
21. In thermochemistry force displacement work is replaced by:
22. Most of the reactions which give stable products are:
23. NaOH + HCl → NaCl + H₂O Enthalpy change in the above reaction is called:
24. The conditions for standard enthalpy change is:
25. The enthalpies of all elements in their standard states are:
26. The enthalpy change for the reaction C₂H₂ + 5/2 O₂ → 2CO₂ + H₂O is brown as enthalpy of:
27. The enthalpy of an element in standard states is:
28. The enthalpy of formation of a compound is:
29. The exothermic process is:
30. The heat of reaction depends upon:
31. The lattice energy of NaCl is:
32. The measurement of enthalpy change at standard conditions means that we should manage the measurement that______.
33. The net heat change in the chemical reaction is the same whether it is brought about in two or more different ways in one or several steps. It is known as:
34. The smallest unit of heat energy is:
35. The spontaneous reaction are usually:
36. The total heat content of a system is called_______.
37. The unit of enthalpy change is:
38. The value of ∆V is very small. The term P∆V can be neglected for the process involving:
39. The values of ∆H for the process I(g) + e-1 → I-1(g) is:
40. What is correct about the heat of combustion:
41. What is not correct about ∆Hf?
42. When a solid melts, there is:
43. Which of the following has a positive value of enthalpy:
44. Which substance has AE = AH and no pressure-volume work:
45. ΔHn for the reaction NaOH + CH₃COOH is:
Short Questions
1. Burning of a candle is a spontaneous process. Justify?
2. Define lattice energy and give examples?
3. Define the following terms: (a) Enthalpy (b) Endothermic reaction.
4. Define ΔHr0 (enthalpy of reaction). Can it be negative? How?
5. Describe Hess’s Law of constant heat summation?
6. How do we determine the ΔH in the laboratory for food, fuel etc?
7. How do you compare law of conservation of energy and Hess’s law of heat summation?
8. How the amount of lattice energy of an ionic compound depends upon the charge densities of the ions?
9. How the lattice energy of the ionic compound can be measured by Born- Haber cycle?
10. How the temperature of the system changes during exothermic and endothermic reaction?
11. How will you differentiate between ΔE and ΔH? Is it true that ΔH and ΔE have the same values for the reactions taking place in the solution state?
12. It is true that a non- spontaneous process never happens in the universe?
13. Specific heat of a substance depends upon the nature of substance. Comment?
14. State first law of thermodynamics and give its mathematical form?
15. The total energy of a system is the sum of translation, rotational and vibration motions. Justify it?
16. What is heat of atomization?
17. What is state and state function?
18. What is the comparison of ΔH. Or state why ΔH= ΔE in a case of liquids and solids?
19. What is the physical significance of equation, ΔH = qp?
20. What is the spontaneous and a non-spontaneous process?
21. Why it is necessary to maintain the physical states of reactants and products in a chemical reaction?
Long Questions
1. What are spontaneous and non-spontaneous processes. Give examples.
"2. What is the first law of thermodynamics. How does it explain that
(i) qáµ¥=∆E (ii) qp=∆H"
3. How will you diferentiate between ∆E and ∆H? Is it true that ∆H and ∆E have the same values for the reactions taking place in the solution state.
4. What is the diference between heat and temperature? Write a mathematical relationship between these two parameters.
5. How do you measure the heat of combustion of a substance by bomb calorimeter.
"6. Deine heat of neutralization. When a dilute solution of a strong acid is neutralized by a dilute solution of a strong base, the heat of neutralization is found to be nearly the same in all the cases.
How do you account for this?"
7. State the laws of thermochemistry and show how are they based on the irst law of thermodynamics.
8. What is a thermochemical equation. Give three examples. What information do they convey?
9. Why is it necessary to mention the physical states of reactants and products in a thermochemical reaction? Apply, Hess’s law to justify your answer.
10. Deine and explain Hess’s law of constant heat summation. Explain it with examples and give its application.
11. Hess’s law helps us, to calculate the heats of those reactions, which cannot be normally carried out in a laboratory. Explain it.
12. What is lattice energy? How does Born-Haber cycle help to calculate the lattice energy of NaCl?
13. Justify that heat of formation of compound is the sum of all the other enthalpies.
14. Calculate the quantity of heat evolved. Also, calculate the heat of combustion of 1 mole of N₂H₄.
15. The temperature of the calorimeter increases from 21.36 ⁰C to 28.78 ⁰C. Calculate the heat of combustion for 1.8g of octane. Also, calculate the heat for 1 mole of octane.
"16. If the heats of combustion of C₂H₄, H₂ and C₂H₆ are -337.2, -68.3 and -372.8k calories respectively, then calculate the heat of the following reaction.
C₂H₄+H₂→C₂H₆"
"17. What is the enthalpy change of the process?
Graphite → Diamond at the same temperature? "
18. What is the meaning of the term enthalpy of ionization? If the heat of neutralization of HCl and NaOH is -57.3 kJ mol⁻¹ and heat of neutralization of CH₃COOH with NaOH is -55.2 kJ mol⁻¹, calculate the enthalpy of ionization of CH₃COOH.
19. Draw a complete, fully labeled Born-Haber cycle for the formation of potassium bromide.
20. What is enthalpy of a reaction? Give one method for its measurement.
21. Describe the measurement of enthalpy of a reaction by glass calorimetric method.
22. Explain glass calorimetric method for the measurement of enthalpy of reaction.
23. Explain with diagram how enthalpy of a reaction can be measured by glass calorimeter.
24. When two moles of H₂ and 1 mole of O₂ at 100 áµ’C and 1 torr pressure react to produce 2 moles of gaseous water, 484.5 kJ of energy as evolved what are values of (a) ∆H (b) ∆E for the production of one mole of H₂O
25. Define enthalpy of combustion. Write its measurement by Bomb Calorimeter.
26. Describe bomb calorimeter, for the calculation of enthalpy of a substance.
27. Define and explain Hess’s Law with example.
28. Explain Hess’s law of constant heat summation with examples and give its applications.
29. Define lattice energy and Born-Haber cycle. How Born Haber cycle help us to measure lattice energy.
30. What is “First law of thermodynamics”? Prove that ∆E = qv
31. Describe Born-Haber cycle for NaCl
32. Prove that qp=∆H
33. Define Enthalpy of solution, Enthalpy of atomization and Enthalpy of neutralization with help of examples.
34. Describe briefly the construction and working of Bomb calorimeter.
35. Give applications of Hess's law.