This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Processes Involving Multiple Units”.
1. A reactor is supplied with 5 moles each of CH3OH and O2, and the following reactions occur, CH3OH + 1/2O2 -> CH2O + H2O and then CH2O + 1/2O2 -> CO + H2O, the conversion of methanol is 80% in first reaction, and conversion of CH2O is 50% in second reaction. How many moles of CO are produced?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of CO = (0.8*5)*0.5 = 2.
2. A reactor is supplied with 5 moles each of CH3OH and O2, and the following reactions occur, CH3OH + 1/2O2 -> CH2O + H2O and then CH2O + 1/2O2 -> CO + H2O, the conversion of methanol is 80% in first reaction, and conversion of CH2O is 50% in second reaction. How many moles of H2O are produced?
a) 2
b) 3
c) 5
d) 6
View answer
Explanation: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of H2O = (0.8*5) + (0.8*5)*0.5 = 6.
3. A reactor is supplied with 5 moles each of CH3OH and O2, and the following reactions occur, CH3OH + 1/2O2 -> CH2O + H2O and then CH2O + 1/2O2 -> CO + H2O, the conversion of methanol is 80% in first reaction, and conversion of CH2O is 50% in second reaction. How many moles of CH2O came out of the reactor?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of CH2O unreacted = 0.8*5 – (0.8*5)*0.5 = 2.
4. A reactor is supplied with 5 moles each of CH3OH and O2, and the following reactions occur, CH3OH + 1/2O2 -> CH2O + H2O and then CH2O + 1/2O2 -> CO + H2O, the conversion of methanol is 80% in first reaction, and conversion of CH2O is 50% in second reaction. How many moles of O2 are there in the products?
a) 1.75
b) 2
c) 3.25
d) 5.5
View answer
Explanation: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of O2 = (2.5 – 2.5*0.8) + (2.5 – 2.5*0.5) = 1.75.
5. A reactor is supplied with 5 moles each of CH3OH and O2, and the following reactions occur, CH3OH + 1/2O2 -> CH2O + H2O and then CH2O + 1/2O2 -> CO + H2O, the conversion of methanol is 80% in first reaction, and conversion of CH2O is 50% in second reaction. How many moles of CH3OH are there in the products?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Extent of reaction E1 = (-0.8)/(-1) = 0.8, E2 = (-0.5)/(-1) = 0.5, => moles of CH3OH = 5 – 5*0.8 = 1.
6. A reactor is supplied with C6H12O6 and the following reactions occur C6H12O6 -> 2C2H5OH + 2CO2 and C6H12O6 –> 2C2H3CO2H + 2H2O, 360 grams of pure glucose is supplied and 44 grams of CO2 was produced, what 90 grams of glucose left unreacted, how many grams of propenoic acid was produced?
a) 18
b) 36
c) 72
d) 144
View answer
Explanation: Weight of glucose reacted in first reaction = (44/44)*(1/2)*180 = 90 grams, => (360 – 90 – 90) = 180 grams of glucose reacted in second reaction, => weight of propenoic acid produced = 2*(180/180)*72 = 144 grams.
7. A reactor is supplied with C6H12O6 and the following reactions occur C6H12O6 -> 2C2H5OH + 2CO2 and C6H12O6 –> 2C2H3CO2H + 2H2O, 360 grams of pure glucose is supplied and 44 grams of CO2 was produced, what 90 grams of glucose left unreacted, how many grams of ethanol was produced?
a) 23
b) 46
c) 92
d) 186
View answer
Explanation: Moles of glucose reacted in first reaction = 90/180 = 0.5, => weight of ethanol produced = 2*0.5*46 = 46 grams.
8. A reactor is supplied with C6H12O6 and the following reactions occur C6H12O6 -> 2C2H5OH + 2CO2 and C6H12O6 –> 2C2H3CO2H + 2H2O, 360 grams of pure glucose is supplied and 44 grams of CO2 was produced, what 90 grams of glucose left unreacted, how many grams of water was produced?
a) 9
b) 18
c) 36
d) 54
View answer
Explanation: Weight of glucose reacted in first reaction = ½*(66/44)*180 = 135 grams => Weight of glucose reacted in second reaction = 360 – 180 – 135 = 45 grams, => moles of water produced = 2*(45/180)*18 = 9 grams.
9. A reactor is supplied with 5 moles of C4H10, and it undergoes following reactions C4H10 + 4H2O -> 4CO + 9H2 and C4H10 + 6.5O2 -> 4CO2 + 5H2O, if 8 moles of CO2 was produced and 2 moles of C4H10 remains unreacted, what are the number of moles of water produced?
a) 2
b) 5
c) 7.5
d) 10
View answer
Explanation: Extent of second reaction = (8 – 0)/4 = 2, => moles of water produced = 5*2 = 10.
10. A reactor is supplied with 5 moles of C4H10, and it undergoes following reactions C4H10 + 4H2O -> 4CO + 9H2 and C4H10 + 6.5O2 -> 4CO2 + 5H2O, if 8 moles of CO2 was produced and 2 moles of C4H10 remains unreacted, what are the number of moles of CO produced?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Extent of second reaction = (8 – 0)/4 = 2, => moles of C4H10 reacted in second reaction = 2*1 = 2, => moles of C4H10 reacted in first reaction = 5 – 2 – 2 = 1, => extent of first reaction = (0 – 1)/(-1) = 1, => moles of CO produced = 4*1 = 4.
11. A reactor is supplied with 12 moles of C, and it undergoes following reactions C + 0.5O2 -> CO and C + O2 -> CO2, if 4 moles of CO2 was produced and 4 moles of C remains unreacted, what are the number of moles of CO produced?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Extent of second reaction = (4 – 0)/1 = 4, => moles of C reacted in second reaction = 4*1 = 4, => moles of C reacted in first reaction = 12 – 4 – 4 = 4, => extent of first reaction = (0 – 4)/(-1) = 4, => moles of CO produced = 4*1 = 4.
12. A reactor is supplied with 15 moles of C, and it undergoes following reactions C + 0.5O2 -> CO and C + O2 -> CO2, if 8 moles of CO2 was produced and 3 moles of C remains unreacted, what are the number of moles of CO produced?
a) 1
b) 2
c) 3
d) 4
View answer
Explanation: Extent of second reaction = (8 – 0)/1 = 8, => moles of C reacted in second reaction = 8*1 = 8, => moles of C reacted in first reaction = 15 – 8 – 3 = 4, => extent of first reaction = (0 – 4)/(-1) = 4, => moles of CO produced = 4*1 = 4.
13. A reactor is supplied with 25 moles of C, and it undergoes following reactions C + 0.5O2 -> CO and C + O2 -> CO2, if 13 moles of CO2 was produced and 5 moles of C remains unreacted, what are the number of moles of CO produced?
a) 1
b) 3
c) 5
d) 7
View answer
Explanation: Extent of second reaction = (13 – 0)/1 = 13, => moles of C reacted in second reaction = 13*1 = 13, => moles of C reacted in first reaction = 25 – 13 – 5 = 7, => extent of first reaction = (0 – 7)/(-1) = 7, => moles of CO produced = 7*1 = 7.
14. A reactor is supplied with 20 moles of C, and it undergoes following reactions C + 0.5O2 -> CO and C + O2 -> CO2, if 10 moles of CO2 was produced and 5 moles of C remains unreacted, what are the number of moles of CO produced?
a) 1
b) 3
c) 5
d) 7
View answer
Explanation: Extent of second reaction = (10 – 0)/1 = 10, => moles of C reacted in second reaction = 10*1 = 10, => moles of C reacted in first reaction = 20 – 10 – 5 = 5, => extent of first reaction = (0 – 5)/(-1) = 5, => moles of CO produced = 5*1 = 5.
15. A reactor is supplied with 45 moles of C, and it undergoes following reactions C + 0.5O2 -> CO and C + O2 -> CO2, if 25 moles of CO2 was produced and 6 moles of C remains unreacted, what are the number of moles of CO produced?
a) 6
b) 9
c) 14
d) 17
View answer
Explanation: Extent of second reaction = (25 – 0)/1 = 25, => moles of C reacted in second reaction = 25*1 = 25, => moles of C reacted in first reaction = 45 – 25 – 6 = 14, => extent of first reaction = (0 – 14)/(-1) = 14, => moles of CO produced = 14*1 = 14.
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