Question

Calculate the standard change in Gibbs free energy for the reaction at 25 °C. Refer to the ΔG°f values.

C2H2(g)+4Cl2(g)⟶2CCl4(l)+H2(g)
Δ°rxn= ? kJ

Answer 1

To calculate ΔG°, use the formula ΔG° = ΔH° - TΔS° and the provided values for ΔH° and ΔS°.

Step-by-step explanation:

To calculate the standard change in Gibbs free energy (ΔG°) for the given reaction, we need to use the formula: ΔG° = ΔH° - TΔS°, where ΔH° is the standard enthalpy change, ΔS° is the standard entropy change, and T is the temperature in Kelvin.

Given the standard enthalpy change (ΔH°) is 50.6 kJ/mol and the standard entropy change (ΔS°) can be calculated as ΔS° = 2 * S°(N₂H₄) - S°(N₂) - 3 * S°(H₂), where S° is the absolute entropy of the reactants and products.

Calculate ΔG° using the formula above and the provided values, and convert it to kJ to find the standard change in Gibbs free energy.

Answer 2

The standard change in Gibbs free energy (ΔG°) for the reaction at 25 °C is -188.28 kJ/mol.

Step-by-step explanation:

To calculate the standard change in Gibbs free energy (ΔG°) for the given reaction, we can use the equation:

ΔG° = ΔH° - TΔS°

where ΔH° is the standard enthalpy change, ΔS° is the standard entropy change, and T is the temperature in Kelvin.

Given that the standard enthalpy change (ΔH°) for the reaction is -187.78 kJ/mol and the standard entropy change (ΔS°) for the reactants and products are:

S°(H₂) = 130.7 J/(mol•K)

S°(O₂) = 205.2 J/(mol•K)

S°(H₂O₂) = 109.6 J/(mol•K)

we can substitute these values into the equation to calculate ΔG°.

ΔG° = -187.78 kJ/mol - (298 K × ((109.6 J/(mol•K)) + (2 × 205.2 J/(mol•K))))

ΔG° = -187.78 kJ/mol - (298 K × (109.6 J/(mol•K) + 410.4 J/(mol•K)))

ΔG° = -187.78 kJ/mol - (298 K × 520 J/(mol•K))

ΔG° = -187.78 kJ/mol - 154960 J/mol

ΔG° = -188.28 kJ/mol

Therefore, the standard change in Gibbs free energy (ΔG°) for the reaction at 25 °C is -188.28 kJ/mol.