This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Heat (Enthalpy) of Reaction”.
1. The standard heat of reaction is a heat of reaction for how many moles of compound?
a) 0
b) 1
c) 2
d) 3
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Explanation: The standard heat of reaction is a heat of reaction for one mole of compound.
2. What is the heat of reaction for CH4 + 2O2 -> CO2 + 2H2O, if heat of formation of CH4, O2, CO2 and H2O are 10 J, 5 J, 6 J, and 12 J respectively?
a) -10 J
b) 10 J
c) -20 J
d) 20 J
View answer
Explanation: Heat of reaction = 2*12 + 6 – 2*5 – 10 = 10 J.
3. What is the heat of reaction for 2H2 + O2 -> 2H2O, if heat of formation of H2, O2, and H2O are 2 J, 5 J, and 10 J respectively?
a) 2 J
b) 5 J
c) 8 J
d) 11 J
View answer
Explanation: Heat of reaction = 2*10 – 2*2 – 5 = 11 J.
4. What is the heat of reaction for C2H4 + 3O2 -> 2CO2 + 2H2O, if heat of formation of C2H4, O2, CO2, and H2O are 10 J, 5 J, 6 J and 2 J respectively?
a) -4 J
b) -2 J
c) 0
d) 4 J
View answer
Explanation: Heat of reaction = 2*2 + 2*6 – 10 – 2*5 = -4 J.
5. What is the heat of reaction for C6H6 + 3H2 -> C6H12, if heat of formation of C6H6, H2, and C6H12 are 25 J, 5 J and 50 J respectively?
a) 10 J
b) 20 J
c) 30 J
d) 35 J
View answer
Explanation: Heat of reaction = 50 – 3*5 – 25 = 10 J.
6. What is the enthalpy of reaction for C + O2 -> CO2, if the conversion of C is 50%, and heat of formation of C, O2, and CO2 are 0, 0 and 10 J.
a) 5 J
b) 10 J
c) 15 J
d) 20 J
View answer
Explanation: Heat of reaction = 10*0.5 – 0 – 0 = 5 J.
7. What is the enthalpy of reaction for CH4 + 2O2 -> CO2 + 2H2O, if the conversion of CH4 is 50%, and heat of formation of CH4, O2, CO2, and H2O are 10 J, 0, 6 J and 4 J?
a) 0
b) 2 J
c) 4 J
d) 6 J
View answer
Explanation: Heat of reaction = 2*4*0.5 + 6*0.5 + 10*0.5 – 2*0 – 10 = 4 + 3 + 5 – 10 = 2 J.
8. What is the enthalpy of reaction for C2H4 + 3O2 -> 2CO2+ 2H2O, if the conversion of CH4 is 50%, and heat of formation of CH4, O2, CO2, and H2O are 10 J, 0, 6 J and 4 J?
a) 0
b) 2 J
c) 5 J
d) 10 J
View answer
Explanation: Heat of reaction = 2*4*0.5 + 2*6*0.5 + 10*0.5 – 0 – 10*0.5 = 10 J.
9. What is the enthalpy of reaction for CO2 + 4H2 -> 2H2O + CH4, if the conversion of CO2 is 50%, and heat of formation of CO2, H2, H2O, and CH4 are 6 J, 0, 4 J and 10 J?
a) 2 J
b) 5 J
c) 6 J
d) 9 J
View answer
Explanation: Heat of reaction = 10*0.5 + 2*4*0.5 + 6*0.5 – 6*0.5 = 9 J.
10. What is the enthalpy of reaction forC6H6 -> 3C2H2, if the conversion of C6H6 is 80%, and heat of formation of C6H6, and C2H2 are 24 J, and 8 J?
a) 0
b) 2.4 J
c) 4.8 J
d) 5.6 J
View answer
Explanation: Heat of reaction = 3*8*0.8 + 24*0.2 – 24*0.8 = 4.8 J.
11. What is the enthalpy change of a reaction at 45oC, if the enthalpy of reactant at 45oC and 25oC are 10 J and 6 J, and enthalpy of product at 45oC and 25oC are 15 J and 8 J, and the enthalpy change of reaction at 25oC is 10 J?
a) 14 J
b) 21 J
c) 27 J
d) 34 J
View answer
Explanation: Heat of reaction = (10 – 6) + (15 – 8) + 10 = 21 J.
12. What is the enthalpy change of a reaction at 35oC, if the enthalpy of reactant at 35oC and 25oC are 18 J and 10 J, and enthalpy of product at 35oC and 25oC are 12 J and 8 J, and the enthalpy change of reaction at 25oC is 15 J?
a) 9 J
b) 14 J
c) 22 J
d) 27 J
View answer
Explanation: Heat of reaction = (18 – 10) + (12 – 8) + 15 = 27 J.
13. What is the enthalpy change of a reaction at 35oC, if the enthalpy of reactant at 35oC and 25oC are 22 J and 15 J, and enthalpy of product at 35oC and 25oC are 10 J and 5 J, and the enthalpy change of reaction at 25oC is 36 J?
a) 12 J
b) 24 J
c) 36 J
d) 48 J
View answer
Explanation: Heat of reaction = (22 – 15) + (10 – 5) + 36 = 7 + 5 + 36 = 48 J.
14. What is the enthalpy change of a reaction at 30oC, if the enthalpy of reactant at 30oC and 25oC are 18 J and 15 J, and enthalpy of product at 30oC and 25oC are 10 J and 8 J, and the enthalpy change of reaction at 25oC is 45 J?
a) 10 J
b) 25 J
c) 50 J
d) 100 J
View answer
Explanation: Heat of reaction = (18 – 15) + (10 – 8) + 45 = 50 J.
15. What is the enthalpy change of a reaction at 90oC, if the enthalpy of reactant at 90oC and 25oC are 60 J and 25 J, and enthalpy of product at 90oC and 25oC are 80 J and 10 J, and the enthalpy change of reaction at 25oC is 5 J?
a) 10 J
b) 50 J
c) 110 J
d) 150 J
View answer
Explanation: Heat of reaction = (60 – 25) + (80 – 10) + 5 = 110 J.
Sanfoundry Global Education & Learning Series – Basic Chemical Engineering.
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