JEE Main 2023 · 1 February · evening · Single correct · +4 / −1
In figure, a straight line is given for Freundrich Adsorption (y=3x+2.505). The value of 1/n and log K are respectively.
- (a) 0.3 and log 2.505
- (b) 3 and 2.505
- (c) 3 and 0.7033
- (d) 0.3 and 0.7033
Answer and solution
Answer (b) 3 and 2.505
Solution
Chemistry ma’am · 4 steps
Take the log of Freundlich's equation and match it to y = mx + c. Slope and intercept come straight out.
- Freundlich isotherm. The isotherm is x/m = K P^(1/n). Take log on both sides to turn it into a straight line.
log x/m = log K + 1/n log P
- Match the line. The graph plots log x/m on the y-axis against log P on the x-axis. Comparing with y = mx + c, the slope is 1/n and the y-intercept is log K. The figure shows the same thing: a rise of 1 over a run of n, and log K marked as the intercept.
- Read the numbers. In y = 3x + 2.505 the slope is 3 and the intercept is 2.505. So 1/n = 3 and log K = 2.505.
- So. The values are 3 and 2.505, which is option (b).
The idea to keep. For any Freundlich log-log plot, the slope is 1/n and the y-intercept is log K itself. Read them directly from the line, and take the antilog only if the question asks for K.
Answer from the NTA final answer key. Solution by PrepWiser.