Calculate G° for each reaction using G°f values.
MnO2(s) + 2 CO(g) Mn(s) + 2 CO2(g)
DGrxn = (n*DGproducts)-(n*DGreactants)
To calculate ΔG° for the given reaction using ΔG°f values (standard Gibbs free energy of formation), you will need the ΔG°f values for each component involved in the reaction.
The standard Gibbs free energy of formation (ΔG°f) is the change in Gibbs free energy that occurs when one mole of a compound is formed from its constituent elements, all in their standard states.
First, let's write down the balanced equation for the reaction:
MnO2(s) + 2 CO(g) → Mn(s) + 2 CO2(g)
Now, we need the ΔG°f values for each compound involved. We can find these values in a table or database of thermodynamic data. Let's say the ΔG°f values are as follows:
ΔG°f [MnO2(s)] = -518.5 kJ/mol (negative because it is the reactant)
ΔG°f [CO(g)] = -137.2 kJ/mol (negative because it is the reactant)
ΔG°f [Mn(s)] = 0 kJ/mol (elements in their standard state have ΔG°f = 0)
ΔG°f [CO2(g)] = -394.4 kJ/mol (negative because it is the reactant)
Now, we can calculate ΔG° for the reaction using the formula:
ΔG°reaction = Σ(ΔG°f products) - Σ(ΔG°f reactants)
Substituting the ΔG°f values, we have:
ΔG°reaction = [ΔG°f (Mn(s)) + 2ΔG°f (CO2(g))] - [ΔG°f (MnO2(s)) + 2ΔG°f (CO(g))]
ΔG°reaction = [0 + 2*(-394.4)] - [-518.5 + 2*(-137.2)]
Simplifying the equation:
ΔG°reaction = -788.8 - (-792.9)
ΔG°reaction = +4.1 kJ/mol (positive because it is the result of the calculation)
Therefore, the standard Gibbs free energy change (ΔG°) for the given reaction is +4.1 kJ/mol.