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Question: The following data were obtained for 1.00 cm samples of a particular chemical. What is the concentration of a 1.00 cm sample that has an absorbance of 0.60? Conc. Abs. 0.50 0.69 0.40 0.55 0.30 0.41 0.20 0.27 2. 3 Concentration (M)

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Answer 1

Here, the relation between conc. and abs. is linear.

Let the for absorbance as , A = mC + C'

Here, A is absorbance , C is concentration, m and C' are constants.

Calculate the value of m from table as follows:

m = (0.69 - 0.55)/(0.5 - 0.4) = 0.14/0.1 = 1.4

Then relation is A = 1.4C + C'

For C = 0.5, A = 0.69 then

0.69 = 1.4*0.5 +C'

C' = - 0.01

Then the relation is A = 1.4C - 0.01

Put A = 0.6 then

0.6 = 1.4C -0.01

1.4C = 0.61

C = 0.4357

Therefore, the required concentration is 0.4357.

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