ThermodynamicsHard
Question
The following is (are) endothermic reaction (s) :
Options
A.combustion of methane
B.decomposition of water
C.dehydrogenation of ethane to rthylene
D.conversion of graphite to diamond
Solution
Combustion reactions are always exothermic.
(b) 2H2O → 2H2 + O2
Four σ - bond (O - H) are broken while 3σ (2H - H, 1 O - O) and one π - bond (O = O)is formed, thus energy is absorbed.
(c)
Two σ - bond (C - H) are broken at the cost of one π (C - C) and one σ (H - H) bond.
(d) Diamond has higher energy than graphite
(b) 2H2O → 2H2 + O2
Four σ - bond (O - H) are broken while 3σ (2H - H, 1 O - O) and one π - bond (O = O)is formed, thus energy is absorbed.
(c)
Two σ - bond (C - H) are broken at the cost of one π (C - C) and one σ (H - H) bond.
(d) Diamond has higher energy than graphite
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