One mole of each of the following compounds is burnt completely in oxygen. Which compound requires the greatest volume of oxygen , measured at the same temperature and pressure , for complete combustion?
A. Carbon monoxide
B. ethane
C. ethene
D. ethanol
F.5 Chem
2008-04-28 9:14 am
回答 (2)
2008-04-28 9:30 am
✔ 最佳答案
The answer is B.Under constant temperature and pressure, the greater the number of moles of a gas, the greater is its volume. (Avogadro’s law)
A. 2CO + O2 → 2CO2
Mole ratio CO : O2 = 2 : 1
No. of moles of O2 required = 1 x (1/2) = 0.5 mol
B. 2C2H6 + 7O2 → 4CO2 + 6H2O
Mole ratio C2H6 : O2 = 2 : 7
No. of moles of O2 required = 1 x (7/2) = 3.5 mol
C. C2H4 + 3O2 → 2CO2 + 2H2O
Mole ratio C2H4 : O2 = 1 : 3
No. of moles of O2 required = 1 x 3 = 3 mol
D. CH3CH2OH + 3O2 → 2CO2 + 3H2O
Mole ratio CH3CH2OH : O2 = 1 : 3
No. of moles of O2 required = 1 x 3 = 3 mol
2008-04-28 9:09 pm
Perhaps It maybe C
The percentage by mass of Carbon in the molecules becomes larger, it will be more difficult to completely combust, the more oxygen is need to combust it completely.
A: 12/(12+16)x100% = 42.9%
B: 24/(24+6) x100% = 80%
C: 24/(24+4) x 100% = 85.7%
D: 24/(24+16+5+1) x 100% = 52.2%
Therefore, C is the answer.
有錯請指教
The percentage by mass of Carbon in the molecules becomes larger, it will be more difficult to completely combust, the more oxygen is need to combust it completely.
A: 12/(12+16)x100% = 42.9%
B: 24/(24+6) x100% = 80%
C: 24/(24+4) x 100% = 85.7%
D: 24/(24+16+5+1) x 100% = 52.2%
Therefore, C is the answer.
有錯請指教
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