The enthalpy change for chemical reaction is denoted as `DeltaH^(Theta)` and `DeltaH^(Theta) = H_(P)^(Theta) - H_(R)^(Theta)`. The relation between enthalpy and internal enegry is expressed by equation:
`DeltaH = DeltaU +DeltanRT`
where `DeltaU =` change in internal enegry `Deltan =` change in number of moles, `R =` gas constant.
For the change, `C_("diamond") rarr C_("graphite"), DeltaH =- 1.89 kJ`, if `6g` of diamond and `6g` of graphite are seperately burnt to yield `CO_(2)` the heat liberated in first case is

Options

A. increase by 0.41 V
B. increase by 59 mV
C. decrease by 0.41 V
D. decrease by 59 mV

Answer

C

Explanation

pH changes from 0 to 7
`therfore[H^(+)]` changes from 1 to `10^(-7)` M.
accordingly `E_(red)` decreases by `0.059log10^(-7)` i.e., `0.059xx(-7)=-0.41"volt"`