Paper: CSIR-NET June 2013 · Subject: Physical Chemistry · Chapter: Chemical Kinetics · Topic: Chemical Kinetics – General · Marks: 2 · Difficulty: Medium
A 0.1 M solution of compound A shows $50 \%$ transmittance when a cell of 1 cm width is used at $\lambda \mathrm{nm}$. Another 0.1 M solution of compound B gives the optical density value of 0.1761 using 1 cm cell at $\lambda_{1} \mathrm{nm}$. What will be the transmittance of a solution that is simultaneously 0.1 M in A and 0.1 M in B using the same cell and at the same wave length? $\quad[\log 20=1.301 ; \log 30=1.4771 ; \log 50=1.699]$
(a)$33.3 \%$
(b)$50 \%$
(c)$66.7 \%$
(d)$70 \%$
Answer
Answer: A ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Absorbances add: A = 0.301 + 0.1761 = 0.4771 = log 3, so T = 1/3 = 33.3 %.