Heat Capacity Equations - Chemical Engineering Questions and Answers

This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Heat Capacity Equations”.

1. Water having C_P = 10 J/^oC, is heated from 10^oC to 50^oC, what is the enthalpy change?
a) 100 J
b) 250 J
c) 400 J
d) 500 J
View answer

Answer: c
Explanation: ∆H = ₁₀∫⁵⁰10.dT = 10*40 = 400 J.

2. Liquid benzene having C_P = 29 J/^oC, is heated from 5^oC to 10^oC, what is the enthalpy change?
a) 29 J
b) 145 J
c) 195 J
d) 290 J
View answer

Answer: b
Explanation: ∆H = ₅∫¹⁰29.dT = 29*5 = 145 J.

3. Ice having C_P = 15 J/^oC, is heated from -10^oC to -4^oC, what is the enthalpy change?
a) 30 J
b) 60 J
c) 90 J
d) 120 J
View answer

Answer: c
Explanation: ∆H = _-10∫^-415.dT = 15*6 = 90 J.

4. Steam having C_P = 105 J/^oC, is heated from 100^oC to 104^oC, what is the enthalpy change?
a) 210 J
b) 420 J
c) 630 J
d) 840 J
View answer

Answer: b
Explanation: ∆H = ₁₀₀∫¹⁰⁴105.dT = 105*4 = 420 J.

5. Cyclohexane having C_P = 48 J/^oC, is heated from 50^oC to 55^oC, what is the enthalpy change?
a) 240 J
b) 480 J
c) 720 J
d) 960 J
View answer

Answer: a
Explanation: ∆H = ₅₀∫⁵⁵48.dT = 48*5 = 240 J.

6. What is the value of C_P – C_V for ideal gases?
a) 0
b) R/2
c) R
d) 2R
View answer

Answer: c
Explanation: For ideal gases C_P = C_V + R.

7. A mixture contains 20% O2 with C_P = 15 J/^oC and 80% CO2 with C_P = 20 J/^oC, what is the average C_P of mixture?
a) 3 J/^oC
b) 9 J/^oC
c) 16 J/^oC
d) 19 J/^oC
View answer

Answer: d
Explanation: Average C_P = 0.2*15 + 0.8*20 = 19 J/^oC.

8. A mixture contains 30% Ar with C_P = 30 J/^oC, 30% N₂ with C_P = 20 J/^oC and 40% CH₄ with C_P = 10 J/^oC, what is the average C_P of mixture?
a) 7 J/^oC
b) 12 J/^oC
c) 19 J/^oC
d) 26 J/^oC
View answer

Answer: c
Explanation: Average C_P = 0.3*30 + 0.3*20 + 0.4*10 = 19 J/^oC.

9. A mixture contains 20% O₂ with C_P = 10 J/^oC, 30% N₂ with C_P = 20 J/^oC and 50% CO₂ with C_P= 40 J/^oC, what is the average C_P of mixture?
a) 20 J/^oC
b) 28 J/^oC
c) 34 J/^oC
d) 42 J/^oC
View answer

Answer: b
Explanation: Average C_P = 0.2*10 + 0.3*20 + 0.5*40 = 2 + 6 + 20 = 28 J/^oC.

10. A mixture contains 20% SO₂ with C_P= 35 J/^oC, 30% NO₃ with C_P = 20 J/^oC and 50% CO₂ with C_P = 40 J/^oC, what is the average C_P of mixture?
a) 12 J/^oC
b) 17 J/^oC
c) 25 J/^oC
d) 33 J/^oC
View answer

Answer: d
Explanation: Average C_P = 0.2*35 + 0.3*20 + 0.5*40 = 7 + 6 + 20 = 33 J/^oC.

11. Heat Capacity of CO₂ is given by 12 + 3T + T², what is the enthalpy change from 0^oC to 6^oC?
a) 169 J
b) 198 J
c) 244 J
d) 360 J
View answer

Answer: b
Explanation: ∆H = ₀∫⁶ (12 + 3T + T²).dT = 12*6 + 3*36/2 + 63/3 = 198 J.

12. Heat Capacity of water is given by 4 + T², what is the enthalpy change from 0^oC to 3^oC?
a) 7 J
b) 14 J
c) 21 J
d) 32 J
View answer

Answer: c
Explanation: ∆H = ₀∫³ (4 + T²).dT = 4*3 + 33/3 = 21 J.

13. C_P-T curve covers 10 J from 2^oC to 10^oC, what is the enthalpy change?
a) 10 J
b) 20 J
c) 80 J
d) 100 J
View answer

Answer: a
Explanation: Enthalpy change is the area covered under C_P-T curve.

14. C_P-T curve of CO₂ forms a rectangle of height 10 J/^oC from 5^oC to 10^oC?
a) 10 J
b) 50 J
c) 100 J
d) 250 J
View answer

Answer: b
Explanation: Enthalpy change is the area covered under C_P-T curve = Area of rectangle = 10*(10 – 5) = 50 J.

15. C_P-T curve of H₂ forms a rectangle of height 20 J/^oC from 4^oC to 5^oC?
a) 20 J
b) 80 J
c) 100 J
d) 140 J
View answer

Answer: c
Explanation: Enthalpy change is the area covered under C_P-T curve = Area of rectangle = 20*(5 – 4) = 20 J.

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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