Question

For the following reaction:

\[\ce{Fe2O3_{(s)} + 3CO_{(g)} -> 2Fe_{(s)} + 3CO2_{(g)}}\]; ΔH⁰ = −29.8 kJ and ΔS⁰ = 15 J K⁻¹. What is the value of \[\ce{ΔS_{(total)}}\] at 298 K?

Options

• 29.8 J K⁻¹

• 298.0 J K⁻¹

• 100.0 J K⁻¹

• 115.0 J K⁻¹

Answer 1

115.0 J K⁻¹

Explanation:

Since the reaction is exothermic, system loses heat to its surroundings. Hence the entropy of the surroundings increases.

ΔH_surr = +29.8 kJ = 29800 J

∴ ΔS_surr = `(Δ"H"_"surr")/"T" = 29800/298` = 100 J K⁻¹

∴ ΔS_Total = ΔS_sys + ΔS_surr

= 15 + 100

= 115 J K⁻¹