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Electrochemistry formula sheet

Every formula in the Electrochemistry chapter for JEE Main, with one line on when it applies. Topic 1 is open to everyone; sign in free to read all 29 and download the PDF.

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How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that formula, and "last" is the latest year one appeared. ★ marks formulas asked 8 or more times.

Galvanic cells and electrode potentials

Daniell cell
3× asked, last 2026
Zn(s)+CuX2+(aq)→ZnX2+(aq)+Cu(s)Ecell∘=1.10 V\begin{aligned}&\ce{Zn(s) + Cu^2+(aq) -> Zn^2+(aq) + Cu(s)}\\&E^\circ_{\text{cell}}=1.10\ \text{V}\end{aligned}
Galvanic: anode oxidation (−), cathode reduction (+). Electrolytic: anode +, still oxidation. Eext>1.10E_{\text{ext}}>1.10 V reverses it.
Cell notation
2× asked, last 2024
Zn(s) ∣ ZnX2+(aq) ∣∣ CuX2+(aq) ∣ Cu(s)\ce{Zn(s) | Zn^2+(aq) || Cu^2+(aq) | Cu(s)}
Anode left, cathode right. || is a salt bridge (KCl or KNOX3\ce{KNO3} in agar).
Standard hydrogen electrode
2× asked, last 2024
Pt(s) ∣ HX2(g) ∣ HX+(aq)  (1 bar, 1 M):E∘=0 V\ce{Pt(s) | H2(g) | H+(aq)}\ \ (1\ \text{bar},\ 1\ \text{M}):\quad E^\circ=0\ \text{V}
Calomel and Ag/AgCl electrodes depend on [ClX−][\ce{Cl-}].
Standard cell potential
7× asked, last 2026
Ecell∘=Ecathode∘−Eanode∘=Eright∘−Eleft∘E^\circ_{\text{cell}}=E^\circ_{\text{cathode}}-E^\circ_{\text{anode}}=E^\circ_{\text{right}}-E^\circ_{\text{left}}
Both reduction potentials. E∘E^\circ is intensive: never multiply by coefficients. Ecell∘>0E^\circ_{\text{cell}}>0: spontaneous.
What decides a metal's E°
4× asked, last 2023
M(s)→ΔsubHM(g)→ΔiHM+(g)→ΔhydHM+(aq)\mathrm{M(s)}\xrightarrow{\Delta_{\text{sub}}H}\mathrm{M(g)}\xrightarrow{\Delta_iH}\mathrm{M^+(g)}\xrightarrow{\Delta_{\text{hyd}}H}\mathrm{M^+(aq)}
Large hydration of LiX+\ce{Li+} makes Li the most negative (−3.05 V).

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24 more formulas in 7 topics

Electrochemical series; Nernst equation; Cell potential, Gibbs energy and K; Conductance; Kohlrausch's law; Electrolysis and Faraday's laws; and Batteries, fuel cells and corrosion. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Electrochemical series

  • Standard reduction potentials (V)7×
  • Displacement and H₂ from acid3×
  • Combining E° of half-reactions8×

Nernst equation

  • Nernst equation17×
  • One electrode4×
  • pH-dependent electrodes16×
  • Concentration cell2×
  • Metal–insoluble salt electrode2×

Cell potential, Gibbs energy and K

  • ΔG and cell potential13×
  • E° and K5×

Conductance

  • Conductivity and cell constant10×
  • Molar conductivity8×
  • Variation with concentration12×
  • Conductometric titration2×

Kohlrausch's law

  • Kohlrausch's law10×
  • Degree of dissociation and Ka6×
  • Solubility from conductivity2×

Electrolysis and Faraday's laws

  • Faraday's first law17×
  • Faraday's second law4×
  • Products of electrolysis9×

Batteries, fuel cells and corrosion

  • Dry cell and mercury cell4×
  • Lead storage and Ni–Cd5×
  • Fuel cell6×
  • Corrosion of iron2×

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About 165 past JEE Main questions from this chapter, with instant answer checking and step-by-step solutions where available. Free, and you can start without signing up.

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