Final answer:
Making a KMnO4 stock solution and diluting it for use ensures consistent concentration, simplifies measurement, avoids difficulties with weighing small amounts, and is cost-effective.
Step-by-step explanation:
The reason for making a stock solution of KMnO4(aq) and diluting it to the needed concentration for each reaction is mainly to ensure a consistent concentration for each reaction (c). When preparing solutions for chemical reactions, having a concentrated stock solution allows for accurate and precise dilutions to be made to achieve specific molarity for multiple reactions.
This approach simplifies the measurement process as it avoids the potential errors and difficulties associated with weighing out small amounts of solid KMnO4 for each individual solution. Moreover, it is cost-effective, as it reduces the overall cost of the reactions by minimizing the waste of chemicals.
By using a stock solution, the calculation of the number of moles of solute involved in the reaction is greatly facilitated since the molarity of the stock solution is known. For dilution, the number of moles of solute remains the same, and only the volume changes, producing a solution of desired molarity.
This process is encapsulated in the formula M1V1 = M2V2, where M1 is the molarity of the stock solution, V1 is the volume of the stock solution used, M2 is the final molarity, and V2 is the final total volume of the solution.