Chemical Engineering Questions and Answers – Solving Energy Balance Problems

This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Solving Energy Balance Problems”.

1. Enthalpy of a stream is which function of temperature and pressure?
a) Explicit
b) Implicit
c) Cannot say
d) None of the mentioned
View answer

Answer: a
Explanation: Enthalpy of a stream is an explicit function of temperature and pressure.

2. In a reaction, the feed is 10 moles of 0.1 glucose and 0.9 water, and another feed of 5 moles of 0.2 glucose and 0.8 water, what is the total moles of product?
a) 5
b) 10
c) 15
d) 20
View answer

Answer: c
Explanation: Total moles of products = 10 + 5 = 15.

3. In a reaction the feed is 10 moles of 0.1 glucose and 0.9 water, and another feed of 5 moles of 0.4 glucose and 0.6 water, what is the fraction of glucose in the products?
a) 0.2
b) 0.4
c) 0.6
d) 0.8
View answer

Answer: a
Explanation: Total moles of products = 10 + 5 = 15, glucose balance: 0.1*10 + 0.4*5 = x*15, => x = 0.2.
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4. In a reaction the feed is 10 moles of 0.1 glucose and 0.9 water, and another feed of 5 moles of 0.4 glucose and 0.6 water, what is the fraction of water in the products?
a) 0.2
b) 0.4
c) 0.6
d) 0.8
View answer

Answer: d
Explanation: Total moles of products = 10 + 5 = 15, water balance: 0.9*10 + 0.6*5 = x*15, => x = 0.8.

5. In a reaction the feed is 5 moles of 0.5 glucose and 0.5 sucrose, and another feed of 15 moles of 0.3 glucose and 0.7 sucrose, what is the fraction of glucose in the products?
a) 0.35
b) 0.45
c) 0.75
d) 0.95
View answer

Answer: a
Explanation: Glucose balance: 5*0.5 + 15*0.3 = x*20, => x = 0.35.
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6. Two feeds, F1 with H = 10 J/mole and F2 with H = 20 J/mole, and product 10 moles with H = 15 J/mole, what is the F1?
a) 5 mole
b) 10 mole
c) 15 mole
d) 20 mole
View answer

Answer: a
Explanation: Energy balance: 10*F1 + 20*F2 = 10*15, => F1 + F2 = 10, => F1 = 5 mole.

7. Two feeds, F1 with H = 10 J/mole and F2 with H = 25 J/mole, and product 15 moles with H = 15 J/mole, what is the F2?
a) 5 mole
b) 10 mole
c) 15 mole
d) 20 mole
View answer

Answer: a
Explanation: Energy balance: 10*F1 + 25*F2 = 15*15, => F1 + F2 = 15, => F2 = 5 mole.
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8. Two feeds, 10 moles with H = 10 J/mole and 5 with H = 25 J/mole, what is the enthalpy of products?
a) 5 J/mole
b) 10 J/mole
c) 15 J/mole
d) 20 J/mole
View answer

Answer: c
Explanation: Energy balance: 10*10 + 5*25 = 15*H, => H = 15 J/mole.

9. Two feeds, 15 moles with H = 10 J/mole and 10 with H = 20 J/mole, what is the enthalpy of products?
a) 8 J/mole
b) 12 J/mole
c) 18 J/mole
d) 25 J/mole
View answer

Answer: c
Explanation: 25*H = 15*10 + 10*20, => H = 18 J/mole.
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10. Two feeds, F1 with H = 10 J/mole and 5 moles with H = 20 J/mole, if the mole of products is 10 what is the enthalpy of products?
a) 10 J/mole
b) 15 J/mole
c) 20 J/mole
d) 25 J/mole
View answer

Answer: b
Explanation: 10*5 + 5*20 = 10*H, => H = 15 J/mole.

11. Three feeds, 10 mole with H = 5 J/mole, 10 mole with H = 15 J/mole and 5 mole with 20 J/mole, what is the enthalpy of the products?
a) 10 J/mole
b) 12 J/mole
c) 15 J/mole
d) 24 J/mole
View answer

Answer: b
Explanation: 25*H = 10*5 + 10*15 + 5*20, => H = 12 J/mole.

12. Three feeds, 10 mole with H = 25 J/mole, 5 mole with H = 10 J/mole and 15 mole with 20 J/mole, what is the enthalpy of the products?
a) 10 J/mole
b) 12 J/mole
c) 20 J/mole
d) 28 J/mole
View answer

Answer: c
Explanation: 30*H = 10*25 + 5*10 + 15*20, => H = 20 J/mole.

13. Three feeds, 10 mole with H = 15 J/mole, 20 mole with H = 5 J/mole and F1 with 20 J/mole, if enthalpy of the products is H = 15 J/mole, what is the value of F1?
a) 10 mole
b) 20 mole
c) 30 mole
d) 40 mole
View answer

Answer: d
Explanation: 10*15 + 20*5 + F1*20 = (30 + F1)*15, => F1 = 40 mole.

14. Two feeds, 10 mole with 5 J/mole and 20 mole with 15 J/mole, product contains two streams, 5 mole with 10 J/mole and P with 25 J/mole, what is the value of P?
a) 10 mole
b) 12 mole
c) 15 mole
d) 18 mole
View answer

Answer: b
Explanation: 10*5 + 20*15 = 5*10 + P*25, => P = 12 mole.

15. Two feeds, 5 mole with 25 J/mole and F with 5 J/mole, product contains two streams, 5 mole with 10 J/mole and 10 mole with 15 J/mole, what is the value of F?
a) 10 mole
b) 15 mole
c) 20 mole
d) 25 mole
View answer

Answer: d
Explanation: 5*25 + F*5 = 5*10 + 10*15, => F = 25 mole.

Sanfoundry Global Education & Learning Series – Basic Chemical Engineering.

To practice all areas of Basic Chemical Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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