The free energy change for the following reactions are given below
`C_(2)H_(2)(g)+(5)/(2)O_(2)(g)to2CO_(2)(g)+H_(2)O(l)`, `DeltaG^(@)=-1234 kJ`
`C(s)+O_(2)(g)toCO_(2)(g)`, `DeltaG^(@)=-394 kJ`
`H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(l)`, `DeltaG^(@)=-237 kJ`
What is the standard free energy change for the reaction
`H_(2)(g)+2C(s)toC_(2)H_(2)(g)` ?

Options

A. `-209 kJ`
B. `-2259 kJ`
C. `+2259 kJ`
D. 209 kJ

Answer

D

Explanation

By `2xx(ii)-(i)+(iii)`
`H_(2(g))+2C_((s))rarrC_(2)H_(2(g)), DeltaG^(@)=209 kJ`.