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Solution:
Using C₁V₁ = C₂V₂:
15% * 100 mL = 5% * V₂
V₂ = (15% * 100 mL) / 5% = (0.15 * 100) / 0.05 = 15 / 0.05 = 300 mL
Answer: The final volume of the diluted solution is 300 mL.
Practice Problem 3
A doctor orders 250 mL of a 12% dextrose solution. The pharmacy has a stock solution of 30%. How much stock solution is needed?
Solution:
Using the formula C₁V₁ = C₂V₂:
30% * V₁ = 12% * 250 mL
V₁ = (12% * 250 mL) / 30% = (0.12 * 250) / 0.30 = 30 / 0.30 = 100 mL
Answer: Use 100 mL of the 30% stock solution.
Tips for Solving Dilution Problems
1. Always convert percentages to decimal form for calculations.
2. Identify what is given and what is required in the problem.
3. Use the dilution formula consistently and double-check your calculations.
Conclusion
Mastering dilution problems is vital for pharmacy professionals to ensure accurate medication preparation. Regular practice with different scenarios will improve confidence and proficiency. Use these practice problems to reinforce your understanding and prepare effectively for certification exams.
Preparing for pharmacy certification exams requires mastering a variety of mathematical concepts, including dilution problems. These problems are essential for pharmacists to accurately prepare and administer medications, ensuring patient safety. This article provides practice sessions focused on dilution problems to help students and professionals strengthen their skills.
Understanding Dilution Concepts
Dilution involves reducing a concentration of a substance in a solution. It is commonly expressed as a ratio or a percentage. The basic formula used in dilution problems is:
C₁V₁ = C₂V₂
Where:
- C₁ = initial concentration
- V₁ = initial volume
- C₂ = final concentration
- V₂ = final volume
Practice Problem 1
A pharmacy needs to prepare 500 mL of a 10% saline solution from a stock solution that is 20%. How much of the stock solution should be used?
Solution:
Using the formula C₁V₁ = C₂V₂:
20% * V₁ = 10% * 500 mL
V₁ = (10% * 500 mL) / 20% = (0.10 * 500) / 0.20 = 50 / 0.20 = 250 mL
Answer: Use 250 mL of the 20% stock solution.
Practice Problem 2
If a pharmacist has 100 mL of a 15% solution and needs to dilute it to 5%, what is the final volume of the diluted solution?
Solution:
Using C₁V₁ = C₂V₂:
15% * 100 mL = 5% * V₂
V₂ = (15% * 100 mL) / 5% = (0.15 * 100) / 0.05 = 15 / 0.05 = 300 mL
Answer: The final volume of the diluted solution is 300 mL.
Practice Problem 3
A doctor orders 250 mL of a 12% dextrose solution. The pharmacy has a stock solution of 30%. How much stock solution is needed?
Solution:
Using the formula C₁V₁ = C₂V₂:
30% * V₁ = 12% * 250 mL
V₁ = (12% * 250 mL) / 30% = (0.12 * 250) / 0.30 = 30 / 0.30 = 100 mL
Answer: Use 100 mL of the 30% stock solution.
Tips for Solving Dilution Problems
1. Always convert percentages to decimal form for calculations.
2. Identify what is given and what is required in the problem.
3. Use the dilution formula consistently and double-check your calculations.
Conclusion
Mastering dilution problems is vital for pharmacy professionals to ensure accurate medication preparation. Regular practice with different scenarios will improve confidence and proficiency. Use these practice problems to reinforce your understanding and prepare effectively for certification exams.