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Butoxors [25]
3 years ago
15

Th e molar absorption coeffi cient of a substance dissolved in water is known to be 855 dm3 mol−1 cm−1 at 270 nm. To determine t

he rate of decomposition of this substance, a solution with a concentration of 3.25 mmol dm−3 was prepared. Calculate the percentage reduction in intensity when light of that wavelength passes through 2.5 mm of this solution.
Chemistry
1 answer:
Olegator [25]3 years ago
3 0

Answer : The percentage reduction in intensity is 79.80 %

Explanation :

Using Beer-Lambert's law :

A=\epsilon \times C\times l

A=\log \frac{I_o}{I}

\log \frac{I_o}{I}=\epsilon \times C\times l

where,

A = absorbance of solution

C = concentration of solution = 3.25mmol.dm^{3-}=3.25\times 10^{-3}mol.dm^{-3}

l = path length = 2.5 mm = 0.25 cm

I_o = incident light

I = transmitted light

\epsilon = molar absorptivity coefficient = 855dm^3mol^{-1}cm^{-1}

Now put all the given values in the above formula, we get:

\log \frac{I_o}{I}=(855dm^3mol^{-1}cm^{-1})\times (3.25\times 10^{-3}mol.dm^{-3})\times (0.25cm)

\log \frac{I_o}{I}=0.6947

\frac{I_o}{I}=10^{0.6947}=4.951

If we consider I_o = 100

then, I=\frac{100}{4.951}=20.198

Here 'I' intensity of transmitted light = 20.198

Thus, the intensity of absorbed light I_A = 100 - 20.198 = 79.80

Now we have to calculate the percentage reduction in intensity.

\% \text{reduction in intensity}=\frac{I_A}{I_o}\times 100

\% \text{reduction in intensity}=\frac{79.80}{100}\times 100=79.80\%

Therefore, the percentage reduction in intensity is 79.80 %

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We need an equation that would relate the concentration of the original solution to that of the desired solution. To solve this we use the equation expressed as follows, 

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Why is a homogeneous mixture not considered a pure substance? Question 6 options: A pure substance can be separated by physical
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<u><em>Answer:</em></u>

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<u><em>Answer:</em></u>

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Hope this Help.

 





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3 years ago
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How many CO2 molecules in 0.0189 mol of CO2?
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