Hello young chemists! 🧪 Today, let’s have a blast learning about Gibbs energy and equilibrium. We’re going to keep it fun, lively, and simple! 🎉

• Equilibrium Constant (K)
  • If >1K>1: Forward reaction is spontaneous 🚀
  • If <1K<1: Reverse reaction is favoured 🔄
  • If =1K=1: Equilibrium is established—no reaction is favoured! 🤷
• Gibbs Energy (ΔG)
  • Negative ΔG: Forward reaction is spontaneous 🚀
  • Positive ΔG: Reverse reaction is favoured 🔄
• Standard Gibbs Energy (Δ�∘ΔG∘)
  • Refers to changes from reactants to products under standard conditions.
  • Standard Conditions: p = 100kPa for gases and c=1moldm⁻³ for aqueous species at 298K.

Dinitrogen dioxide, N₂​O₂​, is so unstable, it’s like a house of cards 🏠💨! Figuring out its Gibbs energy change of formation, ∘ΔGf∘​, directly is a no-go. But don’t worry, we can use the equilibrium constant, K, and a bit of chemistry magic to find it out!

👩‍🔬 Worked Example

• Given: 2NO(g) ⇌ N₂​O₂​(g) with  = 1.39 ×10⁻⁵ at 298K.
• To Find Δ∘
  • Use: ΔG∘= − RTlnK
  • Substitute values and remember, R = 8.31JK⁻¹mol⁻¹
  • Solution: ΔG∘ = 27.7kJmol⁻¹
• To Find ∘ΔG_f∘​ forN₂​O₂​(g)
  • Use the given ∘ΔGf∘​ for NO(g) which is 87.6 kJmol⁻¹.
  • Solution: ∘(NO)=202.9 kJmol−1ΔGf∘​(NO)=202.9kJmol⁻¹

• A Graphic Display Calculator (GDC) can help you with solving equations, especially when finding equilibrium constants.
• Example: If you have a reaction with  ΔG∘ = − 0.82kJmol⁻¹ at 298K, use your GDC to find K by solving  ΔG∘ = − RTlnK.