ThermodynamicsHard
Question
In which of the following reactions, standard reaction entropy changes (ᐃSo) is positive and standard Gibb′s energy changes (ᐃGo) decreases sharply with increasing temperature ?
Options
A.C (graphite) + 1/2O2(g) → CO(g)
B.CO(g) + 1/2 O2(g) → CO(g)
C.Mg(s) + 1/2 O2(g) → MgO(s)
D.1/2 C (graphite) + 1/2 O2(g) → 1/2CO2 (g)
Solution
Amonge the given reactions only in the case of
C (graphite) + 1/2 O2(g) → CO(g)
entropy increases because randomness (disorder) increases Thus, standard entropy changes (ᐃSo) is positive.
Moreover, it is a combustion reaction and all thecombustion reactions are generally exothermic, i.e.,
ᐃHo = - ve
We know that
ᐃGo = ᐃHo - TᐃSo
ᐃGo = - ve - T(+ ve)
Thus as the temperature increases, the the value of ᐃGo decreases.
C (graphite) + 1/2 O2(g) → CO(g)
entropy increases because randomness (disorder) increases Thus, standard entropy changes (ᐃSo) is positive.
Moreover, it is a combustion reaction and all thecombustion reactions are generally exothermic, i.e.,
ᐃHo = - ve
We know that
ᐃGo = ᐃHo - TᐃSo
ᐃGo = - ve - T(+ ve)
Thus as the temperature increases, the the value of ᐃGo decreases.
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