question_answer

\[\Delta {{G}^{o}}\,vs\,\,\,T\]plot in the Ellinghams diagram slopes downwards for the reactions:

A)  \[Mg+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}MgO\]

B)  \[2Ag+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}A{{g}_{2}}O\]

C)  \[C+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}CO\]

D)  \[CO+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}C{{O}_{2}}\]

Correct Answer: A

Solution :

Reaction (i) \[M(s)+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}MO(s)\] Reaction (ii) \[CO(g)+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}C{{O}_{2}}(g)\] Reaction (iii) \[C(s)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow{{}}C{{O}_{2}}(g)\] \[\Delta {{G}^{o}}\] vs, T plot in the Ellinghams diagram slopes downwards for the reaction (I) and reaction (II). For reaction (III) \[\Delta {{G}^{o}}\] vs T in the diagram slopes upwards.