Mastering Dilution Calculations for Stock Solutions

Understanding dilution calculations is essential for accurately preparing solutions in chemistry. This guide will cover the fundamental concepts of dilution, provide clear examples, and demonstrate how to perform dilution calculations effectively.
By Jamie

Understanding Dilution Calculations

Dilution is the process of reducing the concentration of a solute in a solution by adding more solvent. This concept is crucial in many fields, including chemistry, biology, and medicine. In this guide, we will explore how to perform dilution calculations for stock solutions, using the dilution formula:

C1V1 = C2V2
Where:

  • C1 = initial concentration of the stock solution
  • V1 = volume of the stock solution to be diluted
  • C2 = final concentration of the diluted solution
  • V2 = final volume of the diluted solution

Example 1: Preparing a Dilute Solution from a Stock Solution

Problem:

You have a stock solution of hydrochloric acid (HCl) with a concentration of 12 M (molarity). You need to prepare 500 mL of a 1 M HCl solution for an experiment. How much of the stock solution do you need to dilute with water?

Solution:

  1. Identify the known values:

    • C1 = 12 M
    • C2 = 1 M
    • V2 = 500 mL

  2. Rearrange the dilution formula to find V1:

    \[V1 = \frac{C2 \times V2}{C1}\]

  3. Plug in the values:

    \[V1 = \frac{1 \text{ M} \times 500 \text{ mL}}{12 \text{ M}} = \frac{500}{12} \approx 41.67 \text{ mL}\]

  4. Therefore, you need to measure approximately 41.67 mL of the 12 M HCl stock solution and dilute it with water to reach a final volume of 500 mL.

Example 2: Calculating the Final Volume of a Diluted Solution

Problem:

You have a stock solution of sodium chloride (NaCl) at a concentration of 5 M. You take 20 mL of this stock solution and dilute it to a final concentration of 0.5 M. What will be the final volume of the diluted solution?

Solution:

  1. Identify the known values:

    • C1 = 5 M
    • C2 = 0.5 M
    • V1 = 20 mL

  2. Rearrange the dilution formula to find V2:

    \[V2 = \frac{C1 \times V1}{C2}\]

  3. Plug in the values:

    \[V2 = \frac{5 \text{ M} \times 20 \text{ mL}}{0.5 \text{ M}} = \frac{100}{0.5} = 200 \text{ mL}\]

  4. Thus, the final volume of the diluted NaCl solution will be 200 mL.

Conclusion

Dilution calculations are essential for preparing solutions with precise concentrations. By using the dilution formula, you can easily determine the amount of stock solution needed and the final volumes of your diluted solutions. With practice, these calculations will become second nature, enhancing your confidence in laboratory settings.