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Surface Chemistry

Section: Chemistry

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Question : 3 of 29

Marks: +1, -0

Adsorption of a gas on solids follows Freundlich adsorption isotherm. The graph drawn between

\log \frac{x}{m}

(on y -axis) and

\log p

(on x -axis) is a straight line with slope equal to 3 and intercept equal to 0.30 . What is the value of

\frac{x}{m}

at a pressure of 2 atm ?

\log 2 = 0.3

[AP EAPCET 23 May 2025 S2]

$48$
$32$
$16$
$8$

Solution:

Freundlich adsorption isotherm:

\frac{x}{m} = k p^{1/n}

Taking

\log

on both sides:

\log \frac{x}{m} = \log k + \frac{1}{n} \log p

Given from the question:

slope

= \frac{1}{n} = 3

intercept

= \log k = 0.30

We are asked to find

\frac{x}{m}

at

p = 2 \text{ atm}

, given

\log 2 = 0.3

.

Step 1: Write the equation

\log \frac{x}{m} = 0.30 + 3 \log p

Step 2: Substitute

\log p = \log 2 = 0.3

\log \frac{x}{m} = 0.30 + 3(0.3)

\log \frac{x}{m} = 0.30 + 0.90 = 1.20

Step 3: Find

\frac{x}{m}

\frac{x}{m} = 10^{1.20}

We know

10^{1.2} = 10 \times 10^{0.2} \approx 10 \times 1.58 = 15.8 \approx 16

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