Question

3. The following reaction is carried out at 25°C and 1 atm. Determine the AGºsys using the thermodynamic data tables. Is the reaction spontaneous? Explain. 2 SO2(g) + O2 (g) → 2 503 (9)

Answer 1

Plan To find the any reaction is spontaneous or non-spontaneous, we must to know the value of Gibb’s free energy. If ΔG_sys<0, the reaction will be spontaneous.

Solution Find the value of ΔG_sys, we can use the following equation,

                                              ΔG_sys = -ΔnRTlnQ……(1)

    Given the equation is,       

25029) + O2(g) → 25039

   Δn = Δn_(product) – Δn_(reactant),           Δn = 2 – (2+1),    Δn = -1mol

R = 8.314 J/K.mol ,      T = 298 K,         Q = [SO₃]² / [SO₂]² * [O₂]

                                                                  Q = [2]² / [2]² * [1], Q = 1

Now putting the all value in equⁿ (1),

ΔG_sys = -(-1) mol * 8.314 J/K*mol * 298 K ln[1]

ΔG_sys = 0

Therefore , the value of ΔG_sys is 0 and the reaction is in equilibrium state.