Question

If 5.0 mL of a Sports Drink with an absorbance reading of 0.34 was diluted with water to 10.0 mL and was read by the colorimeter, what is the expected absorbance of the solution

Answer 1

Answer:

the expected absorbance of the solution = 0.17

Explanation:

From the information given:

Using Beer's Lambert Law, we have

A = ∈CL

where;

A = Absorbance

∈ = extinction coefficient

C = concentration

L = cell length

Since Absorbance is associated with concentration.

Assuming the measurement were carried out in the same solution; Then  ∈ and L will be constant and A  ∝ C ----- (1)

Let consider the concentration to be C  (mol/L)

5.0 mL of a Sports Drink = 5.0 mL × C (mol)/1000 mL

= 5C/1000 mL

was diluted with water to 10.0 mL

So, when diluted with water to 10.0 mL; we have:

The new concentration to be : $\dfrac{(5 C \times 1000) \ mol }{(1000 \times 10 \times 1000)\ mL}$

Since :1000mL = 1 L

The new concentration = $\dfrac{C \ mol }{2 \ L}$

As stated that the initial absorbance reading $A_1$ = 0.34

The expected absorbance reading will be $A_2$ = ???

From (1)

A ∝ C

∴

$\dfrac{A_2}{A_1}=\dfrac{C_2}{C}$

$A_2 = \dfrac{A_1}{C}$

$A_2 = \dfrac{0.34}{2}$

$A_2 = 0.17$

Thus ; the expected absorbance of the solution = 0.17