Question

A sample of 2,4-hexadiene in methanol in a 2.5 cm cell shows an
absorbance of 0.65 at 240.0 nm. What is the concentration of the
diene? The molar absorption at this wavelength is 12100 dm3 mol1
cm1.

Answer 1

A sample of 2,4-hexadiene in methanol in a 2.5 cm cell shows an

absorbance of 0.65 at 240.0 nm. What is the concentration of the

diene? The molar absorption at this wavelength is 12100 dm3 mol1

cm1.

Answer 2

Answer:The molar concentration of diene is $2.14\times 10^{-5} mol/L$.

Explanation;

$A=\epsilon \times c\times l$

Absorbance of the solution at 240 nm = 0.65

Molar concentration of diene = c

Length of the cell = 2.5 cm

The molar absorption at this wavelength =$\epsilon=12100 dm^3 mol^{-1}cm^{-1}$

$c=\frac{A}{\epsilon \times l}=\frac{0.65}{12100 dm^3 mol^{-1}cm^{-1}\times 2.5 cm}=2.14\times 10^{-5} mol dm^{-3}=2.14\times 10^{-5} mol/L$

$1dm^3= 1L$

The molar concentration of diene is $2.14\times 10^{-5} mol/L$.