1. Balanced Chemical Equation:

First, we need to balance the chemical equation:

S + 1.5 O₂ → SO₃

2. Mole Ratio:

From the balanced equation, we see that 1.5 moles of O₂ react to produce 1 mole of SO₃.

3. Calculation:

Since you have 1.2 moles of O₂ consumed, we can set up a proportion:

(1 mole SO₃ / 1.5 moles O₂) = (x moles SO₃ / 1.2 moles O₂)

Solving for x:

x moles SO₃ = (1 mole SO₃ / 1.5 moles O₂) * (1.2 moles O₂) = 0.8 moles SO₃

Therefore, 0.8 moles of SO₃ would be produced when 1.2 moles of oxygen are consumed.