urgent (tomorrow) applying Beer-Lambert Law

Hi,

I don't understand how to do this question so if someone could go through it with me would be great :smile:

"A swimmer enters a gloomy pool and as he dives down it gets gloomier. If the mean molar absorption coefficient of the pond water in the visible region is 6.2 x 10^-5 dm³ mol^-1 cm^-1, calculate the depth at which he will experience:

(a) half of the surface intensity of light
(b) one tenth that intensity"

Reply 1

markkey

8

The beer-lambert equation is A=Ecl
A = Absorbance
E = Molar absorption co efficient
C = Concentration (conc of water in water = 1000/18= 55.56mol dm^-3)
and L = Length

Part a)
Abosrbance = log₁₀initial light/final light
Absorbance = log₁₀2/1
Absorbance = 0.301

Rearrange A=Ecl to make l the subject l=A / Ec = 0.301 / 6.2x10^-5x55.56 = 87.388cm

Part b)
Abosrbance = log₁₀initial light/final light
Absorbance = log₁₀10/1
Absorbance = 1

Rearrange A=Ecl to make l the subject l=A / Ec = 1 / 6.2x10^-5x55.56 = 276.9cm

Reply 2

supreme

OP

4

markkey

The beer-lambert equation is A=Ecl
A = Absorbance
E = Molar absorption co efficient
C = Concentration (conc of water in water = 1000/18= 55.56mol dm^-3)
and L = Length

Part a)
Abosrbance = log₁₀initial light/final light
Absorbance = log₁₀2/1
Absorbance = 0.301

Rearrange A=Ecl to make l the subject l=A / Ec = 0.301 / 6.2x10^-5x55.56 = 87.388cm

Part b)
Abosrbance = log₁₀initial light/final light
Absorbance = log₁₀10/1
Absorbance = 1

Rearrange A=Ecl to make l the subject l=A / Ec = 1 / 6.2x10^-5x55.56 = 276.9cm

Thanks very much I understand it now :smile:

urgent (tomorrow) applying Beer-Lambert Law

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