Question

(a) The student dissolves the entire impure sample of CuSO4(s) in enough distilled water to make 100.mL of solution. Then the student measures the absorbance of the solution and observes that it is 0.30. Determine the concentration of CuSO4(aq) in the solution.

Answer 1

Answer:

Explanation:

Given parameters :

Volume of solution  = 100mL

Absorbance of solution  = 0.30

Unknown:

Concentration of CuSO₄ in the solution = ?

Solution:

There is relationship between the absorbance and concentration of a solution. They are directly proportional to one another.

A graph of absorbance against concentration gives a value of 0.15M at an absorbance of 0.30.

The concentration is 0.15M

Also, we can use:  Beer-Lambert's law;

                    A  = ε mC l

where εm is the molar extinction coefficient

             C is the concentration

             l is the path length

Since the εm is not given and assuming path length is 1;

         Then we solve for the concentration.