Calculate the degree of dissociation ( ∝ ) of acetic acid, if its molar conductivity ( Ʌ m ) is 39 . 05 S cm 2 mol - 1 . Given: λ ° ( H + ) = 349 . 6 S cm 2 mol - 1 and λ ° ( CH 3 COO - ) = 40 . 9 S cm 2 mol - 1 .

Given, The molar conductivity, λ ° ( H + ) = 349 . 6 S cm 2 mol - 1 . The molar conductivity, λ ° ( CH 3 COO - ) = 40 . 9 S cm 2 mol - 1 . The molar conductivity, λ ° ( CH 3 COOH ) = λ ° ( CH 3 COO - ) + λ ° ( H + ) = 40 . 9 + 349 . 6 = 390 . 5 S cm 2 mol - 1 . The molar conductivity, Ʌ m = 39 . 05 S cm 2 mol - 1 . The degree of dissociation will be calculated as, α = Ʌ m λ ° ( CH 3 COOH ) = 39 . 05 S cm 2 mol - 1 390 . 5 S cm 2 mol - 1 = 0 . 1 .

Calculate the emf and ΔG for the given cell at 25 ° C : Cr s / Cr 3 + 0 . 1 M / / Fe 2 + 0 . 01 M / Fe s . Given: E Cr 3 + / Cr ° = - 0 . 74 V ; E Fe 2 + / Fe ° = - 0 . 44 V ; [ 1 F = 96500 C ; R = 8 . 314 J K - 1 mol - 1 ] .

Given, The concentration of Cr 3 + = 0 . 1 M . The concentration of Fe 2 + = 0 . 01 M . E Cr 3 + / Cr ° = - 0 . 74 V . E Fe 2 + / Fe ° = - 0 . 44 V . E Cell ° = E Cathode ° - E Anode ° = - 0 . 44 + 0 . 74 = 0 . 3 V . 1 F = 96500 C . R = 8 . 314 J K - 1 mol - 1 . The cell reaction will be 2 Cr ( s ) + 3 Fe 2 + ( aq ) → 3 Fe ( s ) + 2 Cr 3 + ( aq ) . The number of electrons involved in this reaction is six. Therefore, the Nernst equation of the above reaction will be, E Cell = E ° Cell + 0 . 0591 n log Cr 3 + 2 Fe 2 + 3 ⇒ E Cell = 0 . 3 V + 0 . 0591 6 log 1 × 10 - 1 2 1 × 10 - 2 3 . E Cell = 0 . 3 V + 0 . 0591 6 log 10 - 2 × 10 6 1 3 . E Cell = 0 . 3 V + 0 . 0591 6 × 4 = 0 . 3 + 0 . 2364 6 . E Cell = 0 . 3 + 0 . 0394 = 0 . 3394 V . The free energy change of the reaction will be, ∆ G = - nFE . ∆ G = - 2 × 96500 × 0 . 3394 . ∆ G = - 65504 . 2 J = - 65 . 504 kJ .

Define the corrosion of metals.

Corrosion of metals– The slow and spontaneous process of the conversion of a metal into an undesirable compound (usually oxide) on exposure to atmospheric conditions is called corrosion of metals.

Define the equivalent conductivity.

Equivalent conductivity is the specific conductance of an aqueous solution containing one equivalent weight of electrolyte dissolved in the solution. Equivalent conductivity is defined as the conducting power of all the ions produced by dissolving one gram equivalent of an electrolyte in solution.

Calculate the emf and ∆ G ∘ for the cell reaction at 25 o C Zn ( s ) | Zn 2 + ( aq ) ( 0 · 1 M ) | | Cd 2 + ( aq ) ( 0 · 01 M ) | Cd ( s ) Given E 𝑍 n 2 + ⁄ 𝑍 n ∘ = − 0 . 763 V and E 𝐶 d + 2 / 𝐶 d ∘ = − 0 . 403 𝑉

Given E 𝑍 n 2 + ⁄ 𝑍 n ∘ = − 0 . 763 V and E 𝐶 d + 2 / 𝐶 d ∘ = − 0 . 403 𝑉 Cell reaction is: Cd + 2 + Zn → Cd + Zn + 2 emf of the cell is, E cell ∘ = 0 . 763 − 0 . 403 = 0 . 360 V ΔG ∘ = − nFE cell ∘ Where, n = 2 and F = Faraday constant = 96485 C / mol ΔG ∘ = − 2 × 96485 × 0 . 36 ΔG ∘ = 69 . 5 kJ

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2018>Q 5

HARD

12th ICSE

IMPORTANT

Earn 100

The specific conductivity of a solution containing $5$ g of anhydrous ${BaCl}_{2}$ ( molecular weight $= 208$ ) in $1000 {cm}^{3}$ of a solution is found to be $0.0058 {ohm}^{- 1} {cm}^{- 1}$ . Calculate the molar and equivalent conductivity of the solution.

Important Questions on Electrochemistry

EASY

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2018>Q 6

What is an electrochemical series? How is it useful in predicting whether a metal can liberate hydrogen from acid or not?

EASY

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2019>Q 7

The cell reaction is spontaneous or feasible when emf of the cell is:

MEDIUM

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2019>Q 8

Calculate the mass of silver deposited at cathode when a current of $2$ amperes is passed through a solution of ${AgNO}_{3}$ for $15$ minutes. (atomic mass: $Ag = 108, 1 F = 96, 500 C$ ).

MEDIUM

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2019>Q 9

Calculate the emf and $∆ G$ for the cell reaction at $298 K$ ·

Question Image

EASY

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2019>Q 10

Define the following terms: Specific conductance.

EASY

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2019>Q 11

Define the following terms: Kohlrausch’s Law.

MEDIUM

12th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 3 - Electrochemistry>ICSE-2019>Q 12

The resistance of a conductivity cell containing $0.001 M KCl$ solution at $298 K$ is $1500 ohm$ . What is the cell constant and molar conductivity of $0.001 M KCl$ solution, if the conductivity of this solution is $0.146 \times 10^{- 3} {ohm}^{- 1} {cm}^{- 1}$ at $298 K$ ?