The question provides a table with the concentrations of five solutions (including the stock solution) and requires us to describe the procedure to prepare these solutions, considering a sequential dillution process.
To solve this question, we need to calculate the volume of each solution required to prepare the following (more diluted) KMnO4 solution. To do that, we'll be using the following equation:
Where C1 and V1 are the concentration and volume of the initial solution, respectively, and C2 and V2 are the concentration and volume of the final solution.
Since the information we need is actually the volume required of the initial solution and the final volume is always 100 mL (as stated by the question), we can rearrange the equation as:
(Note that C2 and C1 are given in the table)
With the equation above, we can calculate the volumes required and fill out the last column of the table:
For flask 1: V1 = [ (0.0054 M) x (100 mL) ] / 0.054 M = 10 mL
For flask 2: V1 = [ (0.00135 M) x (100 mL) ] / 0.0054 M = 25 mL
For flask 3: V1 = [ (0.0002025 M) x (100 mL) ] / 0.00135 M = 15 mL
For flask 4: V1 = [ (0.0000405 M) x (100 mL) ] / 0.0002025 M = 20 mL
Now that we know the required volumes to prepared all solutions in a sequential dilution process, we can describe the procedure as it follows:
a. To prepare a 0.0054 M KMnO4 solution: use a 10 mL volumetric pipette to transfer 10 mL of the stock solution to a 100mL volumetric flask (Flask 1), then complete the volumetric flask with water.
b. To prepare a 0.00135 M KMnO4 solution: use the 25 mL volumetric pipette to transfer this volume of the solution from flask 1 (0.0054 M) to a clean 100 mL volumetric flask (Flask 2) then complete the flask with water.
c. To prepare a 0.0002025 M KMnO4 solution: use the 15 mL volumetric pipette to transfer this volume of the solution from flask 2 (0.00135 M) to a clean 100 mL volumetric flask (Flask 3) then complete the flask with water.
d. To prepare a 0.0000405 M KMnO4 solution: use the 20 mL volumetric pipette to transfer this volume of the solution from flask 3 (0.0002025 M) to a clean 100 mL volumetric flask (Flask 4) then complete the flask with water.