E°cell ↔ ΔrG° ↔ K: one triangleE°cell ↔ ΔrG° ↔ K: एक त्रिभुजE°cell ↔ ΔrG° ↔ K: ek triangle

Class 12 Chemistry · Chapter 2 · interactive diagram

Parts and what they mean

• Standard cell potential E°cell (मानक सेल विभव E°cell) — Measured with a voltmeter (no current drawn). Intensive: does not depend on how the equation is multiplied.
• Standard Gibbs energy ΔrG° (मानक गिब्ज़ ऊर्जा ΔrG°) — Extensive: doubles if the equation is doubled. Negative ΔrG° = spontaneous.
• Equilibrium constant K (साम्य स्थिरांक K) — At equilibrium the cell voltage is zero. Daniell cell: K = 2 × 10³⁷.
• ΔrG° = −nFE°cell (ΔrG° = −nFE°cell) — n = electrons in the balanced reaction, F = 96487 C mol⁻¹. Daniell cell: −2 × 96487 × 1.1 = −212.27 kJ mol⁻¹.
• E°cell = (0.059/n) log K at 298 K (298 K पर E°cell = (0.059/n) log K) — Put E = 0 in the Nernst equation. Cu + 2Ag⁺: log K = 2 × 0.46/0.059 = 15.6.
• ΔrG° = −RT ln K = −2.303RT log K (ΔrG° = −RT ln K = −2.303RT log K) — Links thermodynamics to equilibrium; R = 8.314 J K⁻¹ mol⁻¹.
• Test for spontaneity (स्वतःप्रवर्तिता की जाँच) — All three agree: E° > 0 ⇔ ΔG° < 0 ⇔ K > 1.

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake