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06/10/2020 3:49 pm
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What will be the heat of formation of methane, if the heat of combustion of carbon is '–x' kJ, heat of formation of water is '–y' kJ, and heat of combustion of methane is 'z' kJ?
(a) (–x – y + z) kJ
(b) (–z – x + 2y) kJ
(c) (–x – 2y – z) kJ
(d) (–x – 2y + z) kJ
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06/10/2020 3:58 pm
(d) (–x – 2y + z) kJ
Explanation:
From given data, we have
C + O2 → CO2 -xkJ ....(i)
H2 + 1/2O2 → H2O - ykJ ....(ii)
CH4 + 2O2 → CO2 + 2H2O + zkJ ....(iii)
The required equation is
C + 2H2 → CH4 + Q
To get the required equation, operate
(i) + 2× (ii) – (iii)
Thus, we get
C + 2H2 → CH4 + [(-x) + (-2y) - (-z)]
Thus, heat of formation of methane is
(–x – 2y + z) kJ