Use tabulated electrode potentials to calculate ΔG∘ for the following reaction: 2Na(s)+2H2O(l)→H2(g)+2OH−(aq)+2Na+(aq) Express the free energy in joules to three significant figures.

Respuesta :

Answer: The [tex]\Delta G^o[/tex] for the given reaction is [tex]-5.23\times 10^5J[/tex]

Explanation:

For the given chemical reaction:

[tex]2Na(s)+2H_2O(l)\rightarrow H_2(g)+2OH^-(aq.)+2Na^+(aq.)[/tex]

Half reactions for the given cell follows:

Oxidation half reaction: [tex]Na(s)\rightarrow Na^{+}+e^-;E^o_{Na^{+}/Na}=-2.71V[/tex]    (  × 2)

Reduction half reaction: [tex]2H^{+}+2e^-\rightarrow H_2(g);E^o_{H^{+}/H}=0.00V[/tex]

Oxidation reaction occurs at anode and reduction reaction occurs at cathode.

To calculate the [tex]E^o_{cell}[/tex] of the reaction, we use the equation:

[tex]E^o_{cell}=E^o_{cathode}-E^o_{anode}[/tex]

Putting values in above equation, we get:

[tex]E^o_{cell}=0.00-(-2.71)=2.71V[/tex]

  • To calculate standard Gibbs free energy, we use the equation:

[tex]\Delta G^o=-nFE^o_{cell}[/tex]

Where,

n = number of electrons transferred = 2

F = Faradays constant = 96500 C

[tex]E^o_{cell}[/tex] = standard cell potential = 2.71 V

Putting values in above equation, we get:

[tex]\Delta G^o=-2\times 96500\times 2.71=-523030J=-5.30\times 10^5J[/tex]

Hence, the [tex]\Delta G^o[/tex] for the given reaction is [tex]-5.23\times 10^5J[/tex]