Calculating the Amount of Stock Solution

Oct 13, 2025 by wbrum.org 75 views

Introduction

Preparing a stock solution is a crucial step in many scientific experiments, particularly in chemistry. A stock solution is a concentrated solution of a substance that is used as a starting point for preparing other solutions with specific concentrations. In this article, we will discuss the correct way to prepare a solution using a stock solution.

Understanding the Problem

A student requires 2.00 L of a 0.100 M NH4NO3 solution from a 1.75 M NH4NO3 stock solution. To prepare this solution, the student needs to determine the correct amount of the stock solution to use and the correct dilution method.

Calculating the Amount of Stock Solution

To calculate the amount of stock solution needed, we can use the dilution formula:

M1V1 = M2V2

where:

M1 is the concentration of the stock solution (1.75 M)
V1 is the volume of the stock solution needed (in liters)
M2 is the desired concentration of the solution (0.100 M)
V2 is the final volume of the solution (2.00 L)

Rearranging the formula to solve for V1, we get:

V1 = (M2V2) / M1

Plugging in the values, we get:

V1 = (0.100 M x 2.00 L) / 1.75 M V1 = 0.114 L

Measuring the Stock Solution

To prepare the solution, the student needs to measure 0.114 L (or 114 mL) of the 1.75 M stock solution. This can be done using a pipette or a burette.

Diluting the Stock Solution

Once the stock solution has been measured, it needs to be diluted to the desired concentration. In this case, the student needs to dilute the 1.75 M solution to 0.100 M.

To dilute the solution, the student can use the following formula:

V2 = V1 x (M1 / M2)

where:

V2 is the final volume of the solution (2.00 L)
V1 is the initial volume of the solution (0.114 L)
M1 is the initial concentration of the solution (1.75 M)
M2 is the final concentration of the solution (0.100 M)

Plugging in the values, we get:

V2 = 0.114 L x (1.75 M / 0.100 M) V2 = 2.00 L

Conclusion

In conclusion, to prepare a 2.00 L solution of 0.100 M NH4NO3 from a 1.75 M stock solution, the student needs to measure 0.114 L (or 114 mL) of the stock solution and dilute it to the desired concentration. This can be done using the dilution formula and a pipette or burette to measure the stock solution.

Tips and Precautions

When preparing a stock solution, it is essential to follow proper laboratory procedures to ensure accuracy and safety. Some tips and precautions to keep in mind include:

Always use a pipette or burette to measure the stock solution accurately.
Use a clean and dry container to prepare the solution.
Label the container clearly with the concentration and volume of the solution.
Store the solution in a cool, dry place to prevent degradation.
Always wear protective gear, such as gloves and goggles, when handling chemicals.

Common Mistakes to Avoid

When preparing a stock solution, there are several common mistakes to avoid. Some of these mistakes include:

Measuring the stock solution incorrectly, resulting in an incorrect concentration.
Failing to dilute the solution correctly, resulting in an incorrect concentration.
Not labeling the container correctly, resulting in confusion and errors.
Not storing the solution properly, resulting in degradation and contamination.

Introduction

Preparing a stock solution is a crucial step in many scientific experiments, particularly in chemistry. A stock solution is a concentrated solution of a substance that is used as a starting point for preparing other solutions with specific concentrations. In this article, we will answer some frequently asked questions about preparing a stock solution.

Q: What is a stock solution?

A stock solution is a concentrated solution of a substance that is used as a starting point for preparing other solutions with specific concentrations.

Q: Why do I need to prepare a stock solution?

Preparing a stock solution allows you to create a concentrated solution of a substance that can be used to prepare other solutions with specific concentrations. This is particularly useful when working with small volumes of a substance or when you need to prepare multiple solutions with different concentrations.

Q: How do I prepare a stock solution?

To prepare a stock solution, you need to measure the correct amount of the substance and dissolve it in a solvent, such as water. The concentration of the stock solution will depend on the amount of substance used and the volume of the solvent.

Q: What is the dilution formula?

The dilution formula is:

M1V1 = M2V2

where:

M1 is the concentration of the stock solution
V1 is the volume of the stock solution needed
M2 is the desired concentration of the solution
V2 is the final volume of the solution

Q: How do I calculate the amount of stock solution needed?

To calculate the amount of stock solution needed, you can use the dilution formula. Rearranging the formula to solve for V1, we get:

V1 = (M2V2) / M1

Q: What is the difference between a stock solution and a working solution?

A stock solution is a concentrated solution of a substance that is used as a starting point for preparing other solutions with specific concentrations. A working solution, on the other hand, is a solution that is prepared from a stock solution and is used for a specific experiment or application.

Q: How do I store a stock solution?

To store a stock solution, you should keep it in a cool, dry place, away from direct sunlight and heat sources. You should also label the container clearly with the concentration and volume of the solution.

Q: What are some common mistakes to avoid when preparing a stock solution?

Some common mistakes to avoid when preparing a stock solution include:

Measuring the stock solution incorrectly, resulting in an incorrect concentration.
Failing to dilute the solution correctly, resulting in an incorrect concentration.
Not labeling the container correctly, resulting in confusion and errors.
Not storing the solution properly, resulting in degradation and contamination.

Q: How do I dispose of a stock solution?

To dispose of a stock solution, you should follow the proper procedures for disposing of hazardous waste. This may include diluting the solution with water, neutralizing it with a base or acid, or disposing of it in a designated hazardous waste container.

Conclusion

Preparing a stock solution is a crucial step in many scientific experiments, particularly in chemistry. By following proper laboratory procedures and avoiding common mistakes, you can ensure that your stock solution is prepared accurately and safely.