Is Electrochemistry and Chemical Kinetics part of the EAPCET Chemistry syllabus?

Yes. Electrochemistry and Chemical Kinetics is taught in Intermediate second year Chemistry, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.

How many Chemistry questions are there in EAPCET?

40 of the 160 questions in the Engineering paper are Chemistry, spread across 24 chapters.

What mistakes do students make in Electrochemistry and Chemical Kinetics?

Multiplying E° by the stoichiometric coefficient when balancing half-reactions — electrode potential is an intensive property and is never scaled. Putting product over reactant the wrong way in the Nernst equation — Q is [products]/[reactants], so for Zn | Cu it is [Zn²⁺]/[Cu²⁺]. Assuming every half-life depends on initial concentration — for first order it is constant, which is how you identify first-order data. Equating order with stoichiometric coefficients — order is found experimentally and can be zero or fractional.

EAPCET Chemistry · Intermediate second year

Electrochemistry and Chemical Kinetics

This chapter combines electrochemistry — cells, electrode potentials and electrolysis — with chemical kinetics — rates, orders and activation energy.

Subject: Chemistry
Taught in: Intermediate second year
Chemistry in the paper: 40 of 160 questions

Key formulas and results

Nernst equation at 298 K: $E = E^\circ - \frac{0.0591}{n} \log Q$
$\Delta G^\circ = -nFE^\circ$
Faraday’s first law: $m = ZIt$
First-order rate constant $k = \frac{2.303}{t} \log\frac{a}{a - x}$ ; half-life $t_{1/2} = \frac{0.693}{k}$
Arrhenius equation: $k = A e^{-E_a/RT}$
Standard EMF and equilibrium constant at 298 K: $E^\circ_{\text{cell}} = \frac{0.0591}{n} \log K$
Conductance and cell constant: $G = \frac{1}{R}$ , $\kappa = G \times \frac{l}{A}$ , resistivity $\rho = \frac{1}{\kappa}$
Molar conductivity: $\Lambda_m = \frac{\kappa \times 1000}{M}$ in $\text{S cm}^2\,\text{mol}^{-1}$ , with $\kappa$ in $\text{S cm}^{-1}$
Degree of dissociation of a weak electrolyte: $\alpha = \frac{\Lambda_m}{\Lambda^\circ_m}$
Kohlrausch’s law: $\Lambda^\circ_m = \lambda^\circ_{\text{cation}} + \lambda^\circ_{\text{anion}}$ ; for strong electrolytes $\Lambda_m = \Lambda^\circ_m - b\sqrt{C}$
Mass deposited in electrolysis: $w = \frac{M \times I \times t}{n \times 96500}$
Half-life and order: $t_{1/2} \propto \frac{1}{a^{n-1}}$ ; zero order $t_{1/2} = \frac{a_0}{2k}$ , second order $t_{1/2} = \frac{1}{k a_0}$
Arrhenius equation at two temperatures: $\log\frac{k_2}{k_1} = \frac{E_a}{2.303R} \times \frac{T_2 - T_1}{T_1T_2}$

What this chapter covers

Galvanic cells and electrode potentials
Nernst equation
Conductance and Kohlrausch’s law
Electrolysis and Faraday’s laws
Rate laws and order
Activation energy and the Arrhenius equation

How it is usually asked

Cell emf
Mass deposited in electrolysis
Molar conductivity
Order, rate constant and half-life
Activation energy

Understanding Electrochemistry and Chemical Kinetics

In a galvanic cell, a spontaneous redox reaction produces electricity: oxidation at the anode (negative) and reduction at the cathode (positive). The cell emf is E°cell = E°cathode − E°anode, using standard reduction potentials. A positive E°cell means ΔG° = −nFE° is negative, so the reaction is spontaneous. The Nernst equation adjusts emf for non-standard concentrations, and at equilibrium E = 0, giving E° = (0.0591/n) log K at 298 K.

Conductance of a solution rises with ion concentration, but molar conductivity rises on dilution. For strong electrolytes it rises only slightly (Λm falls linearly with √c); for weak electrolytes it rises steeply, so Λ°m is found with Kohlrausch’s law of independent migration of ions. In electrolysis, Faraday’s laws link charge to products: one faraday, 96 500 C, is the charge of one mole of electrons, and mass deposited = (charge/96 500) × (molar mass/n).

Chemical kinetics measures how fast reactions go. The rate law, found by experiment, gives the order, which need not match the stoichiometric coefficients. A first-order reaction has a constant half-life, t½ = 0.693/k, independent of starting concentration; a zero-order reaction has t½ = [A]₀/2k. Rate rises with temperature because more molecules exceed the activation energy, as described by the Arrhenius equation; a catalyst lowers Ea without changing ΔH.

Worked example

EAPCET-style question

For the Daniell cell $\text{Zn} \mid \text{Zn}^{2+}(0.1\ \text{M}) \parallel \text{Cu}^{2+}(0.001\ \text{M}) \mid \text{Cu}$ with $E^\circ_{\text{cell}} = 1.10\ \text{V}$ , the emf at 298 K is:

(1)0.98 V
(2)1.04 V
(3)1.10 V
(4)1.16 V

Solution

Cell reaction: $\ce{Zn + Cu^2+ -> Zn^2+ + Cu}$ , with $n = 2$ .
Nernst: $E = E^\circ - \frac{0.0591}{n} \log\frac{[\ce{Zn^2+}]}{[\ce{Cu^2+}]}$ .
$\frac{[\ce{Zn^2+}]}{[\ce{Cu^2+}]} = \frac{0.1}{0.001} = 100$ , so $\log 100 = 2$ .
$E = 1.10 - \frac{0.0591}{2} \times 2 = 1.10 - 0.059 = 1.041\ \text{V} \approx 1.04\ \text{V}$ .
1.16 V comes from inverting $Q$ , and 0.98 V from taking $n = 1$ .

Answer: 1.04 V

Shortcuts and results to remember

First-order reactions: $t_{75\%} = 2\,t_{1/2}$ , $t_{87.5\%} = 3\,t_{1/2}$ , $t_{99.9\%} \approx 10\,t_{1/2}$ and $t_{99\%} = 2\,t_{90\%}$ ; zero-order reactions: $t_{75\%} = 1.5\,t_{1/2}$ and $t_{100\%} = 2\,t_{1/2}$ .
Units of the rate constant for order $n$ are $(\text{mol L}^{-1})^{1-n}\,\text{s}^{-1}$ : zero order $\text{mol L}^{-1}\,\text{s}^{-1}$ , first order $\text{s}^{-1}$ , second order $\text{L mol}^{-1}\,\text{s}^{-1}$ .
Temperature coefficient: $\frac{k_2}{k_1} = \mu^{\Delta T/10}$ , where $\mu$ is usually about 2 (range 1.5 to 3), so a 10 °C rise roughly doubles the rate.
A metal–metal ion concentration cell has $E^\circ_{\text{cell}} = 0$ , so $E = \frac{0.0591}{n} \log\frac{C_{\text{cathode}}}{C_{\text{anode}}}$ , and it works only when the cathode side is more concentrated.
Molecularity is always a whole number from 1 to 3 and applies to elementary steps only; order can be zero or fractional and must be found by experiment.

Common mistakes to avoid

Multiplying E° by the stoichiometric coefficient when balancing half-reactions — electrode potential is an intensive property and is never scaled.
Putting product over reactant the wrong way in the Nernst equation — Q is [products]/[reactants], so for Zn | Cu it is [Zn²⁺]/[Cu²⁺].
Assuming every half-life depends on initial concentration — for first order it is constant, which is how you identify first-order data.
Equating order with stoichiometric coefficients — order is found experimentally and can be zero or fractional.

How to prepare it

The units of the rate constant tell you the order of the reaction — a quick way to check options.

Once the formulas feel familiar, test them the way the exam does: practise Electrochemistry and Chemical Kinetics questions chapter-wise, then attempt a full previous year paper to see whether it holds up under a 3-hour timer.

Related Chemistry chapters

See every chapter in the EAPCET Chemistry syllabus.

Practise Electrochemistry and Chemical Kinetics chapter-wise

Chapter-wise quizzes show exactly which topics in this chapter you still get wrong — before a full paper does.

Frequently asked questions

Is Electrochemistry and Chemical Kinetics part of the EAPCET Chemistry syllabus?: Yes. Electrochemistry and Chemical Kinetics is taught in Intermediate second year Chemistry, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.
How should I prepare Electrochemistry and Chemical Kinetics for EAPCET?: The units of the rate constant tell you the order of the reaction — a quick way to check options.
How many Chemistry questions are there in EAPCET?: 40 of the 160 questions in the Engineering paper are Chemistry, spread across 24 chapters.
What mistakes do students make in Electrochemistry and Chemical Kinetics?: Multiplying E° by the stoichiometric coefficient when balancing half-reactions — electrode potential is an intensive property and is never scaled. Putting product over reactant the wrong way in the Nernst equation — Q is [products]/[reactants], so for Zn | Cu it is [Zn²⁺]/[Cu²⁺]. Assuming every half-life depends on initial concentration — for first order it is constant, which is how you identify first-order data. Equating order with stoichiometric coefficients — order is found experimentally and can be zero or fractional.