Question

Daniella prepares a 1 mg/ml 1 mg/ml myoglobin solution. The molecular weight of myoglobin is 17.8 kDa. 17.8 kDa. Given that the ϵ ϵ of myoglobin is 15 , 000 M − 1 cm − 1 , 15,000 M−1cm−1, calculate the absorbance of the myoglobin solution across a 1 cm 1 cm path. Calculate your answer to two decimal places.

Answer 1

Answer:

A = 0.84

Step-by-step explanation:

The absorbance of the myoglobin solution can be calculated by using the Beer-Lambert law:

$A = \epsilon*C*l$

Where:

A: is the absorbance

ε: is the molar attenuation coefficient = 15,000 M⁻¹cm⁻¹

l: is the  optical path length = 1 cm

C: is the concentration = 1 mg/ml  

Since the concentration is given in mg/ml and the molar attenuation coefficient is given in M (mol/L) we need to convert the concentration in mg/ml to mol/L and for that, we need to use the molecular weight of myoglobin = 17.8 kDa = 17.8x10³ g/mol:    

$C = 1 \frac{mg}{ml} \cdot \frac{1 g}{1000 mg} \cdot \frac{1000 ml}{1 L} \cdot \frac{1 mol}{17.8\cdot 10^{3} g} = 5.62 \cdot 10^{-5} mol/L$

Now, we can calculate the absorbance of the myoglobin:

$A = 15,000 L*mol^{-1}*cm^{-1}*5.62\cdot 10^{-5} mol*L^{-1}*1 cm = 0.84$

Therefore, the absorbance of the myoglobin solution is 0.84.

I hope it helps you!