Electrochemistry Decoded: 100 EAMCET One-Liners to Master Cells, Nernst & Batteries! Engaging Introduction: *”Struggling with Electrochemistry for EAMCET? This ultimate guide breaks down NCERT’s Unit 2 into 100 crisp one-liners covering galvanic cells, Nernst equation, conductance, and batteries—perfect for last-minute revision! With tables, key comparisons, and exam-focused FAQs , you’ll master concepts like Kohlrausch’s law, and corrosion mechanisms in no time. Let’s spark your rank-boosting potential!”*
Here are 100 one-liner questions and answers covering all aspects of Electrochemistry tailored for EAMCET/EAPCET exam preparation:
1. Basics of Electrochemistry No. Question Answer 1 What is electrochemistry? Study of the relationship between electrical energy and chemical reactions. 2 What is an electrochemical cell? A device that converts chemical energy into electrical energy (or vice versa). 3 What are the two types of electrochemical cells? Galvanic (Voltaic) cell and Electrolytic cell. 4 What is the main difference between a galvanic cell and an electrolytic cell? Galvanic cells produce electricity from spontaneous reactions, while electrolytic cells use electricity to drive non-spontaneous reactions. 5 What is the function of a salt bridge in a galvanic cell? Maintains electrical neutrality and completes the circuit.
2. Galvanic Cells & Electrode Potential No. Question Answer 6 What is a galvanic cell? An electrochemical cell that derives electrical energy from spontaneous redox reactions. 7 What is the standard hydrogen electrode (SHE)? Reference electrode with zero potential at 1 atm H₂, 1M H⁺, and 298K. 8 What is the standard electrode potential? The potential difference of an electrode when connected to SHE under standard conditions. 9 How is the standard cell potential (E°cell) calculated? E°cell = E°cathode – E°anode. 10 What is the SI unit of cell potential? Volt (V).
3. Nernst Equation & Applications No. Question Answer 11 What is the Nernst equation? ( E_{cell} = E°_{cell} – \frac{0.0591}{n} \log Q ) (at 298K). 12 What does ‘Q’ represent in the Nernst equation? Reaction quotient (ratio of product to reactant concentrations). 13 What happens to cell potential when concentration of reactants increases? Ecell increases. 14 What is the cell potential at equilibrium? Zero (Ecell = 0). 15 How is equilibrium constant (K) related to E°cell? ( \log K = \frac{nE°_{cell}}{0.0591} ).
4. Conductance & Kohlrausch’s Law No. Question Answer 16 Define resistivity (ρ). Resistance offered by a conductor of unit length and unit cross-sectional area. 17 What is conductivity (κ)? Reciprocal of resistivity (( κ = \frac{1}{ρ} )). 18 What is molar conductivity (Λₘ)? Conductivity per unit molar concentration (( Λₘ = \frac{κ}{C} )). 19 How does molar conductivity vary with dilution? Increases with dilution. 20 What is Kohlrausch’s law? ( Λₘ° = λ₊° + λ₋° ) (sum of limiting ionic conductances).
5. Electrolysis & Faraday’s Laws No. Question Answer 21 What is electrolysis? Decomposition of an electrolyte by passing electric current. 22 State Faraday’s first law of electrolysis. ( W = ZIt ) (Z = electrochemical equivalent). 23 What is the charge on 1 mole of electrons? 1 Faraday (96500 C). 24 What is the relationship between Gibbs energy and E°cell? ( ΔG° = -nFE°_{cell} ). 25 How is the amount of substance deposited during electrolysis calculated? Using ( W = \frac{MIt}{nF} ).
6. Batteries & Fuel Cells No. Question Answer 26 What is a primary battery? Non-rechargeable battery (e.g., Dry cell). 27 Give an example of a secondary battery. Lead-acid battery. 28 What is the anode in a dry cell? Zinc container. 29 What is the cathode reaction in a fuel cell? ( O₂ + 2H₂O + 4e⁻ → 4OH⁻ ). 30 What is the main advantage of a fuel cell? High efficiency and no pollution.
7. Corrosion No. Question Answer 31 What is corrosion? Deterioration of metals due to electrochemical reactions. 32 What is rusting of iron? Formation of hydrated ferric oxide (( Fe₂O₃·xH₂O )). 33 How does galvanization prevent corrosion? Coating iron with zinc to act as a sacrificial anode. 34 What is cathodic protection? Connecting the metal to a more reactive metal to prevent oxidation. 35 What is the role of oxygen in rusting? Acts as an oxidizing agent.
Tabular Comparison of Galvanic & Electrolytic Cells Feature Galvanic Cell Electrolytic Cell Energy Conversion Chemical → Electrical Electrical → Chemical Reaction Type Spontaneous Non-spontaneous Anode Charge Negative Positive Cathode Charge Positive Negative Example Daniell cell Electrolysis of water
Additional Important One-Liners (Q36-Q100)
What is the E°cell for a spontaneous reaction? → Positive.What is the effect of temperature on cell potential? → Depends on ΔS (Nernst equation).What is overvoltage? → Extra voltage needed for electrolysis beyond theoretical value.What is a mercury cell? → Primary cell with Zn-Hg anode and HgO cathode.What is the electrolyte in a lead-acid battery? → H₂SO₄.
Here are the remaining one-liner questions and answers covering Electrochemistry for EAMCET/EAPCET :
Batteries & Fuel Cells (Continued) No. Question Answer 36 What is the anode in a lithium-ion battery? Graphite (intercalated Li⁺). 37 What is the electrolyte in a lithium-ion battery? Lithium salt in organic solvent. 38 Why are fuel cells eco-friendly? Only byproduct is water (in H₂-O₂ fuel cell). 39 What is the reducing agent in a fuel cell? Hydrogen (H₂). 40 What is the oxidizing agent in a fuel cell? Oxygen (O₂).
Corrosion (Continued) No. Question Answer 41 What is the chemical formula of rust? Fe₂O₃·xH₂O. 42 How does painting prevent corrosion? Forms a barrier against O₂ and moisture. 43 What is anodic protection? Making metal the anode to form a passive oxide layer. 44 What is pitting corrosion? Localized corrosion forming small pits. 45 Why does corrosion occur faster in saline water? NaCl increases conductivity, speeding up redox reactions.
Electrochemical Series & Applications No. Question Answer 46 What is the electrochemical series? Arrangement of metals by standard reduction potentials. 47 Which metal is the strongest reducing agent? Lithium (most negative E°). 48 Which ion is the strongest oxidizing agent? Fluorine (F₂, highest E°). 49 Can Cu²⁺ oxidize Zn to Zn²⁺? Yes (E°Cu²⁺/Cu > E°Zn²⁺/Zn). 50 Why is gold used in jewelry? Least reactive (very positive E°).
Conductivity & Kohlrausch’s Law (Continued) No. Question Answer 51 What is the unit of molar conductivity? S cm² mol⁻¹. 52 Why does Λₘ increase with dilution? Reduced ion-ion interactions. 53 What is Λₘ°? Molar conductivity at infinite dilution. 54 How is Λₘ° for CH₃COOH calculated? Λₘ°(CH₃COOH) = Λₘ°(CH₃COO⁻) + Λₘ°(H⁺). 55 What is the ionic mobility? Speed of an ion under unit electric field.
Electrolysis (Continued) No. Question Answer 56 What is deposited at the cathode during CuSO₄ electrolysis? Copper (Cu). 57 What is the product at the anode in NaCl electrolysis? Cl₂ gas. 58 What is overpotential? Extra voltage needed for gas evolution (e.g., H₂, O₂). 59 Why is Na not obtained by aqueous NaCl electrolysis? H₂O reduces instead of Na⁺ (lower E°). 60 What is the Faraday constant? 96500 C mol⁻¹.
Numericals & Calculations No. Question Answer 61 Calculate E°cell for Zn Zn²⁺ 62 Find ΔG° for a cell with E°cell = 0.80V and n=2. ΔG° = -nFE° = -2 × 96500 × 0.80 = -154.4 kJ . 63 If Λₘ° for NaCl is 126.5 S cm² mol⁻¹, what is λ°(Na⁺) if λ°(Cl⁻) = 76.3? λ°(Na⁺) = 126.5 – 76.3 = 50.2 S cm² mol⁻¹ . 64 How much Ag is deposited by 1A current in 1 hour? (Z = 0.001118 g/C). W = ZIt = 0.001118 × 1 × 3600 = 4.025 g . 65 Find Q if Ecell = 0.50V, E°cell = 0.80V, n=2. 0.50 = 0.80 – (0.0591/2)log Q → Q ≈ 3.2 × 10¹⁰ .
Miscellaneous No. Question Answer 66 What is a calomel electrode? Reference electrode with Hg/Hg₂Cl₂/KCl. 67 What is the role of MnO₂ in a dry cell? Depolarizer (removes H₂ gas). 68 Why is platinum used in SHE? Inert and conducts electricity. 69 What is the E° for SHE? 0.00 V. 70 What is the charge of 1 mole of Al³⁺ ions? 3 × 96500 C = 289500 C .
Tabular Summary: Primary vs. Secondary Batteries Feature Primary Battery Secondary Battery Rechargeable? No Yes Example Dry cell, Mercury cell Lead-acid, Li-ion Cost Cheaper Expensive Lifespan Single use Multiple cycles
Remaining One-Liners (Q71-Q100)
What is the anode in a mercury cell? → Zn-Hg amalgam.What is the cathode in a mercury cell? → HgO + C.What is the electrolyte in a mercury cell? → KOH-ZnO paste.What is the voltage of a dry cell? → ~1.5 V.What is the voltage of a lead-acid battery? → ~2 V per cell.What is the product at the anode in water electrolysis? → O₂ gas.What is the product at the cathode in water electrolysis? → H₂ gas.What is the standard state for E° measurements? → 1M solution, 1 atm, 298K.What is the effect of increasing temperature on Λₘ? → Increases (faster ion movement).What is the order of Λₘ° for H⁺, Na⁺, K⁺? → H⁺ > K⁺ > Na⁺ (due to high H⁺ mobility).What is the unit of cell constant? → cm⁻¹.How is cell constant calculated? → ( \frac{l}{A} ) (distance/area between electrodes).What is the relationship between κ and Λₘ? → ( Λₘ = \frac{κ × 1000}{C} ).What is the charge on 0.5 moles of Ca²⁺ ions? → 1 F (2 × 0.5 × 96500 C).What is the emf of a cell at equilibrium? → 0 V.What is the E°cell for a non-spontaneous reaction? → Negative.What is the role of a potentiometer? → Measures emf without current flow.What is the Nernst equation for Mg|Mg²⁺||Ag⁺|Ag? → ( E_{cell} = E°_{cell} – \frac{0.0591}{2} \log \frac{[Mg^{2+}]}{[Ag^+]^2} ).What is the product of CuSO₄ electrolysis using Cu electrodes? → Anode: Cu dissolves; Cathode: Cu deposits.What is the product of CuSO₄ electrolysis using Pt electrodes? → Anode: O₂; Cathode: Cu.What is the Faraday’s second law? → ( \frac{W_1}{W_2} = \frac{E_1}{E_2} ) (E = equivalent weight).What is the equivalent weight of Al in Al³⁺ + 3e⁻ → Al? → Molar mass/3 = 27/3 = 9 g eq⁻¹ .What is the charge required to deposit 1 mole of Al? → 3 F = 289500 C.What is the condition for metallic conduction? → Flow of electrons in solids.What is the condition for electrolytic conduction? → Movement of ions in solutions.What is the order of Λₘ° for HCl, NaCl, CH₃COOH? → HCl > NaCl > CH₃COOH (strong vs. weak electrolyte).What is the SI unit of κ? → Siemens per meter (S m⁻¹).What is the use of a voltmeter in a cell? → Measures potential difference.What is the role of H₂SO₄ in a lead-acid battery? → Electrolyte and participates in redox.What is the product at the anode in a lead-acid battery? → PbSO₄ (from PbO₂).
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