Consider the reaction
CO(g) + H2O(g) <--> CO2(g) + H2(g)
Use the appropriate tables to calculate
a) delta-G*f at 552*C
b) K at 552*C
I'm pretty sure I have a good idea of how to do this: I believe I can use Gibbs-Helmholtz equation to account for the temperatures... however, what I have a question on is this:
1. Can the Gibbs-Helmholtz equation be used for delta-G*f?
2. How would I use this if I have 2 reactants?
delta Go poducts - delta Go reactants = delta Go rxn.
delta G = delta Go + RTln Q.
At equilibrium, delta G = 0 and ln Q = ln K, so
delta Go = -RT ln K.
To calculate delta-G*f at 552°C, you would need to use the appropriate tables or data sources that provide the standard Gibbs free energy of formation (delta-G*f) values for each species involved in the reaction. These values represent the change in Gibbs free energy when one mole of each compound is formed from its constituent elements in their standard states.
The Gibbs-Helmholtz equation, which relates the standard Gibbs free energy change to temperature, can indeed be used for delta-G*f. It states:
delta-G*f = delta-H*f - T(delta-S)f
where delta-H*f is the standard enthalpy of formation and delta-S*f is the standard entropy of formation.
However, in this case, you are given the reaction equation rather than the formation equation for each substance. The formation equation represents the formation of a compound from its constituent elements in their standard states, whereas the reaction equation describes the interconversion of substances. Therefore, you cannot directly use the Gibbs-Helmholtz equation to calculate delta-G*f using the given reaction equation.
Instead, you would need to use delta-G values at the given temperature. You can calculate delta-G (not delta-G*f) for the reaction using the formula:
delta-G = delta-G° + RT ln Q
where delta-G° is the standard Gibbs free energy change for the reaction at standard conditions (usually given at 298 K), R is the gas constant, T is the temperature (in Kelvin), and Q is the reaction quotient. At equilibrium, delta-G = 0, and ln Q = ln K, so you can rearrange the equation to:
delta-G° = -RT ln K
Given the reaction equation and the temperature of 552°C, you can look up the standard Gibbs free energy values (delta-G°) for each species involved in the reaction at the given temperature. Then you can use the above equation to calculate delta-G° and subsequently K.