In which of the following reactions,standard reaction entropy change`(DeltaS^(@))`is positive and standard Gibb,s energy change`(DeltaG^(@))`decreases sharply with increasing temperature?

Options

A. C( graphite) `+ (1)/(2) O_(2)(g) rarrCO(g0`
B. `CO(g) + (1)/(2) O_(2)(g) rarr CO(g)`
C. `CO(g) + (1)/(2) O_(2)(g) rarr CO_(2)(g)`
D. `Mg(s) + (1)/(2) O_(2)(g) rarr MgO(s)`

Answer

A

Explanation

As reaction (a) isaccompanied by increase in the number o f moles of gaseous substances,entropy increases, i.e., `DeltaS^(@)= + ve`. ,brgt From the relation , `DeltaG^(@) = DeltaH^(@) - TDeltaS^(@)` ,as temperature increases,`T DeltaS^(@)` increases sharply andhence, `DeltaG^(@)` decreases sharply.