Practice With Practice: Geometric Dilution Calculation Questions

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Understanding how to perform geometric dilution calculations is essential for students and professionals dealing with solutions in chemistry and pharmacy. These calculations help determine the concentration of a solution after dilution, which is a common task in laboratories.

What Is Geometric Dilution?

Geometric dilution involves reducing the concentration of a solution by mixing a specific volume of the original solution with a diluent, such as water or another solvent. The process is based on the principle that the total amount of solute remains constant, but the volume increases, leading to a lower concentration.

Key Formula for Geometric Dilution

The fundamental formula used in geometric dilution calculations is:

C1 × V1 = C2 × V2

Where:

  • C1 = initial concentration
  • V1 = volume of the initial solution used
  • C2 = final concentration after dilution
  • V2 = total volume after dilution

Practice Questions

Try solving these common geometric dilution problems to strengthen your understanding.

Question 1

You have 10 mL of a 5% solution. How much water must you add to dilute it to a 1% solution?

Question 2

A pharmacist prepares 250 mL of a 2% solution from a stock solution of 10%. What volume of the stock solution is needed?

Question 3

If you dilute 20 mL of a 3% solution to a final volume of 100 mL, what is the concentration of the diluted solution?

Solutions to Practice Questions

Solution to Question 1

Using the formula: C1 × V1 = C2 × V2

5% × 10 mL = 1% × V2

V2 = (5% × 10 mL) / 1% = 50 mL

Water to add = V2 – V1 = 50 mL – 10 mL = 40 mL

Solution to Question 2

Using the formula: C1 × V1 = C2 × V2

10% × V1 = 2% × 250 mL

V1 = (2% × 250 mL) / 10% = 50 mL

Solution to Question 3

Using the formula: C1 × V1 = C2 × V2

3% × 20 mL = C2 × 100 mL

C2 = (3% × 20 mL) / 100 mL = 0.6%

Conclusion

Practicing geometric dilution calculations enhances your ability to accurately prepare solutions in various scientific fields. Remember to carefully identify your initial concentrations and volumes, and apply the formula consistently for reliable results.