Beer-lambert law

Question 1

What are the 4 parts of a spectroscopy experiment?

Answer 1

Detector
Sample
Dispersive element
Light source

Question 2

What is a dispersive element?

Answer 2

Separates white light into its constituent colours

Question 3

Why do most spectra use absorbance on the y axes?

Answer 3

it can be accurately calibrated

Question 4

The higher the concentration of an absorber…

Answer 4

The less light is transmitted

Question 5

The greater the path length of light through an absorber…

Answer 5

The less light is transmitted

Question 6

What does the molar absorption coefficient measure?

Answer 6

Absorption probability

Question 7

What does the molar absorption coefficient depend on?

Answer 7

Wavelength and type of molecular transition

Question 8

What are the units used for molar absorption coefficient?

Answer 8

M⁻¹ cm⁻¹
or
dm³ mol⁻¹ cm⁻¹

Question 9

What is the beer-lambert law equation? What are the constituents and the

Answer 9

A = εlc 
A = absorbance 
ε = molar absorbance coefficient (M⁻¹ cm⁻¹)
l = length of pathway (cm)
c = concentration of given solution (moldm-3)

Question 10

What is I₀?

Answer 10

Intensity of incident light

Question 11

What is Iᵀ?

Answer 11

Intensity of transmitted light

Question 12

What is Iₐ?

Answer 12

Intensity of absorbed light

Question 13

What is A?

Answer 13

Absorbance

Question 14

What equation links I₀, Iᵀ and A?

Answer 14

I₀ / Iᵀ = 10ᴬ

Question 15

What is concentration proportional to?

Answer 15

Both absorbance and path length of cell

Question 16

Does A have units?

Answer 16

No

Dimensionless

Question 17

What significant figures should you use?

Answer 17

At least the precise number given

Question 18

What are the axes on a beer-lambert plot?

Answer 18

Y axis - Log10[100/Iᵀ]

X axis - concentration

Question 19

What is the gradient equal to on a beer lamber plot?

Answer 19

εl