Hess’s law: burning carbon in one step or twoहेस का नियम: कार्बन का एक या दो चरणों में दहन

NCERT Sec 5.4.4 · interactive diagram

Parts and their functions

• Initial state (प्रारंभिक अवस्था) — C(graphite) + O₂(g).
• Direct route (सीधा मार्ग) — C + O₂ → CO₂; ΔH = −393.5 kJ mol⁻¹.
• Step 1 (चरण 1) — C + ½O₂ → CO; ΔH₁ = −110.5 kJ mol⁻¹ (hard to measure directly — found by Hess’s law).
• Intermediate (मध्यवर्ती) — CO(g) + ½O₂(g).
• Step 2 (चरण 2) — CO + ½O₂ → CO₂; ΔH₂ = −283.0 kJ mol⁻¹.
• Final state (अंतिम अवस्था) — Enthalpy is a state function, so the total change is the same by any route: ΔH = ΔH₁ + ΔH₂.

Original diagram drawn by Simple Learning Hub, based on NCERT Sec 5.4.4. Report a mistake