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Electrochemistry question

2021 · 17 Mar · Shift 2 · Q13
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Electrochemistry question

2021 · 17 Mar · Shift 2 · Q13

JEE MainChemistryElectrochemistryNumerical+4 / −1
A KCl solution of conductivity 0.14 S m −-− 1 shows a resistance of 4.19 Ω\OmegaΩ in a conductivity cell. If the same cell is filled with an HCl solution, the resistance drops to 1.03 Ω\OmegaΩ. The conductivity of the HCl solution is ‾×\underline{\hspace{2cm}}\times​× 10 −-− 2 S m −-− 1. (Round off to the Nearest Integer).
Numerical answer
View written solutionFree

Correct answer: 57

  1. Use the conductivity cell relation

For a conductivity cell,

κ=cell constantR\kappa = \frac{\text{cell constant}}{R}κ=Rcell constant​

So,

cell constant=κR\text{cell constant} = \kappa Rcell constant=κR


  1. Find the cell constant using KCl solution

Given for KCl:

  • Conductivity, κKCl=0.14 S m−1\kappa_{\text{KCl}} = 0.14\ \text{S m}^{-1}κKCl​=0.14 S m−1
  • Resistance, RKCl=4.19 ΩR_{\text{KCl}} = 4.19\ \OmegaRKCl​=4.19 Ω

Hence,

cell constant=0.14×4.19=0.5866 m−1\text{cell constant} = 0.14 \times 4.19 = 0.5866\ \text{m}^{-1}cell constant=0.14×4.19=0.5866 m−1


  1. Use the same cell for HCl solution

For HCl:

  • Resistance, RHCl=1.03 ΩR_{\text{HCl}} = 1.03\ \OmegaRHCl​=1.03 Ω

Therefore,

κHCl=cell constantRHCl=0.58661.03\kappa_{\text{HCl}} = \frac{\text{cell constant}}{R_{\text{HCl}}} = \frac{0.5866}{1.03}κHCl​=RHCl​cell constant​=1.030.5866​

κHCl≈0.5695 S m−1\kappa_{\text{HCl}} \approx 0.5695\ \text{S m}^{-1}κHCl​≈0.5695 S m−1


  1. Express in the required form

We need

κHCl=‾×10−2 S m−1\kappa_{\text{HCl}} = \underline{\hspace{1cm}} \times 10^{-2}\ \text{S m}^{-1}κHCl​=​×10−2 S m−1

Now,

0.5695=56.95×10−20.5695 = 56.95 \times 10^{-2}0.5695=56.95×10−2

Rounded to the nearest integer:

57×10−2 S m−157 \times 10^{-2}\ \text{S m}^{-1}57×10−2 S m−1


  1. Final answer

The required integer is:

57\boxed{57}57​

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