Question

Synthetic natural gas (SNG) thermochemical reaction.

a) ΔH = -74.8 kJ
b) ΔH = -283.0 kJ
c) ΔH = -96.3 kJ
d) ΔH = -285.8 kJ

Answer 1

The reaction '2 H₂(g) + O₂(g) → 2 H₂O(g)' is spontaneous at both 298.15K and 330K as the calculated ΔG values are negative.

Step-by-step explanation:

The question is asking about the spontaneity of the reaction:

2 H₂(g) + O₂(g) → 2 H₂O(g)

To determine if a reaction is spontaneous, we can calculate the change in Gibbs free energy (ΔG) at a given temperature using the equation:

ΔG = ΔH - TΔS

If the calculated ΔG value is negative, the reaction is spontaneous. If it is positive, the reaction is non-spontaneous. If it is zero, the reaction is at equilibrium.

Let's calculate ΔG at 298.15K and at 330K:

ΔH = (-241.82 kJ/mol) * 2 + (-393.5 kJ/mol) = - 188.96 kJ/mol

For 298.15K:

ΔG = -188.96 kJ/mol - (298.15 K)(-228.59 J/K)(1 kJ/1000 J) = -132.79 kJ/mol

For 330K:

ΔG = -188.96 kJ/mol - (330 K)(-228.59 J/K)(1 kJ/1000 J) = -107.79 kJ/mol

Since both ΔG values are negative, it means that the reaction is spontaneous at both 298.15K and 330K.