Question

Beer-Lambert Law

a)

Describe why the molecule carbon dioxide is “active” in the IR range while the major constituents of air (N2, O2) are inactive. Why does CO2’s IR spectrum have two distinct regions of IR absorptivity?

b)

The Beer-Lambert law describes the relationship between absorptivity and concentration of a gas. Compute the concentration of CO2 (in ppm) for the following scenario:

Io= 55 W/m², I = 49 W/m², = 30 ×10⁴ cm²/mol, l (length of cell) = 8 cm.

c)

The stand and deviation on the measurements of absorbance in part b) are ± 4 W/m². How long of a cell length would you need to ensure that the difference between Io and I measurements for the scenario described in b) are at least 3 times the standard deviation?

Answer 1

Cante to

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