Ergosterol, a precursor of vitamin D, has δmax = 282 nm and molar absorptivity ε = 11,900 M-1cm-1. What is the concentration of ergosterol in a solution whose absorbance A = 0.93 with a sample pathlength l = 1.00 cm. M. What is the absorbance of a solution having a concentration of ergosterol of 4.1×10-5 M with a sample pathlength l = 1.00 cm?

1) is the concentration of ergosterol in a solution.

2) The absorbance of the solution is 0.49.

Explanation:

Using Beer-Lambert's law :

Formula used :

where,

A = absorbance of solution

C = concentration of solution =

l = path length = 1.00 cm

= molar absorptivity coefficient

1)

We have:

Absorbance of the solution ,A = 0.93

Concentration of ergosterol ,C = ?

Path length ,l = 1.00 cm

is the concentration of ergosterol in a solution.

2)

We have:

Absorbance of the solution ,A = ?

Concentration of ergosterol ,C =

Path length ,l = 1.00 cm

The absorbance of the solution is 0.49.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

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