Question

The rate of disappearance of SO₂ in the reaction \[\ce{2SO2 + O2 -> 2SO3}\] is 1.28 × 10⁻³ mol dm⁻³ s⁻¹. Then the rate of formation of SO₃ is ____________ mol dm⁻³ s⁻¹.

Options

• 0.64 × 10⁻³

• 0.80 × 10⁻³

• 1.28 × 10⁻³

• 1.60 × 10⁻³

Answer 1

The rate of disappearance of SO₂ in the reaction \[\ce{2SO2 + O2 -> 2SO3}\] is 1.28 × 10⁻³ mol dm⁻³ s⁻¹. Then the rate of formation of SO₃ is 1.28 × 10⁻³ mol dm⁻³ s⁻¹.

Explanation:

\[\ce{2SO2 + O2 -> 2SO3}\]

The average rate of disappearance of SO₂

= `-(Δ["SO"_2])/(Δ"t")`

= 1.28 × 10⁻³ mol dm⁻³ s⁻¹

The average rate of formation of SO₃

= `(Δ["SO"_3])/(Δ"t")`

The average rate of reaction is

`-1/2 (Δ["SO"_2])/(Δ"t") = -(Δ["O"_2])/(Δ"t") = 1/2 (Δ["SO"_3])/(Δ"t")`

∴ `-(Δ["SO"_2])/(Δ"t") = (Δ["SO"_3])/(Δ"t")` = 1.28 × 10⁻³ mol dm⁻³ s⁻¹