Practice Quiz: Dilution Calculation Scenarios With Complete Solutions

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Welcome to this practice quiz on dilution calculations. This article provides multiple scenarios to help you master the concepts of dilution, along with complete solutions for each problem. Whether you’re a student preparing for exams or a teacher creating lesson plans, these examples will enhance your understanding of dilution processes in chemistry.

Understanding Dilution

Dilution involves reducing the concentration of a solute in a solution, usually by adding solvent. The key formula used in dilution calculations is:

C1 × V1 = C2 × V2

Where:

  • C1 = initial concentration
  • V1 = initial volume
  • C2 = final concentration
  • V2 = final volume

Practice Scenarios with Solutions

Scenario 1: Diluting a Stock Solution

You have 50 mL of a 10 M stock solution of hydrochloric acid (HCl). You want to prepare 200 mL of a 2 M solution. How much of the stock solution do you need to use?

Solution:

Using the dilution formula:

10 M × 50 mL = 2 M × V2

V2 = (10 M × 50 mL) / 2 M = 250 mL / 2 = 25 mL

Therefore, you need to take 25 mL of the stock solution and dilute it with solvent to reach a total volume of 200 mL.

Scenario 2: Preparing a Diluted Solution

You have 100 mL of a 5 M sodium hydroxide (NaOH) solution. You want to dilute it to a concentration of 1 M. How much of the original solution should you use to prepare 250 mL of the diluted solution?

Solution:

Applying the formula:

5 M × V1 = 1 M × 250 mL

V1 = (1 M × 250 mL) / 5 M = 50 mL

Thus, you should use 50 mL of the 5 M NaOH solution and dilute it to a total volume of 250 mL.

Scenario 3: Concentration Adjustment

A scientist has 150 mL of a 4 M solution of sulfuric acid (H2SO4). They need to dilute it to 1 M. How much of the original solution is required to prepare 300 mL of the new solution?

Solution:

Using the formula:

4 M × 150 mL = 1 M × V2

V2 = (4 M × 150 mL) / 1 M = 600 mL

Since the required volume is 300 mL, but the calculation indicates a need for 600 mL of the original solution to reach 1 M concentration, it shows you need to take 150 mL of the 4 M solution and dilute it to 300 mL to achieve the desired concentration. The calculation confirms that:

V1 = (1 M × 300 mL) / 4 M = 75 mL

Therefore, you should use 75 mL of the original 4 M solution and dilute it to 300 mL.

Conclusion

Practice with these scenarios will help you become proficient in dilution calculations. Remember to carefully identify the known values and apply the formula accurately. Mastery of dilution is essential in laboratory work, quality control, and various scientific research fields.