A Stock Solution Is Made By Dissolving 66.05 G Of \[$\left( \text{NH}_4\right)_2 \text{SO}_4\$\] In Enough Water To Make 250 ML Of Solution. A 10.0 ML Sample Of This Solution Is Then Diluted To 50.0 ML. Given That The Molar Mass Of

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A Stock Solution and Dilution: Understanding the Concept of Concentration

In chemistry, a stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations. The process of dilution involves reducing the concentration of a solution by adding a solvent, such as water, to it. In this article, we will explore the concept of a stock solution and dilution, and how to calculate the concentration of a solution after dilution.

What is a Stock Solution?

A stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations. Stock solutions are typically made by dissolving a known amount of a substance in a solvent, such as water, to create a solution of a specific concentration. The concentration of a stock solution is usually expressed in terms of the amount of substance per unit volume of solution, such as grams per milliliter (g/mL) or moles per liter (M).

Preparing a Stock Solution

To prepare a stock solution, a known amount of a substance is dissolved in a solvent to create a solution of a specific concentration. The amount of substance used to prepare the stock solution is typically expressed in terms of its molar mass, which is the mass of one mole of the substance. The molar mass of a substance can be calculated by summing the atomic masses of its constituent atoms.

Calculating the Concentration of a Stock Solution

To calculate the concentration of a stock solution, we need to know the amount of substance used to prepare the solution and the volume of the solution. The concentration of a stock solution can be calculated using the following formula:

C = (m / V) x 1000

where C is the concentration of the solution in g/mL, m is the mass of the substance used to prepare the solution in grams, and V is the volume of the solution in milliliters.

Dilution

Dilution is the process of reducing the concentration of a solution by adding a solvent, such as water, to it. The process of dilution involves mixing a known volume of a concentrated solution with a known volume of a solvent to create a solution of a specific concentration.

Calculating the Concentration of a Diluted Solution

To calculate the concentration of a diluted solution, we need to know the concentration of the stock solution, the volume of the stock solution used to prepare the diluted solution, and the volume of the diluted solution. The concentration of a diluted solution can be calculated using the following formula:

C = (C_stock x V_stock) / V_diluted

where C is the concentration of the diluted solution in g/mL, C_stock is the concentration of the stock solution in g/mL, V_stock is the volume of the stock solution used to prepare the diluted solution in milliliters, and V_diluted is the volume of the diluted solution in milliliters.

Example Problem

A stock solution is made by dissolving 66.05 g of {\left( \text{NH}_4\right)_2 \text{SO}_4$}$ in enough water to make 250 mL of solution. A 10.0 mL sample of this solution is then diluted to 50.0 mL. Given that the molar mass of {\left( \text{NH}_4\right)_2 \text{SO}_4$}$ is 132.14 g/mol, calculate the concentration of the diluted solution.

Step 1: Calculate the concentration of the stock solution

First, we need to calculate the concentration of the stock solution. We can do this by dividing the mass of the substance used to prepare the solution by the volume of the solution.

C_stock = (m / V) x 1000 = (66.05 g / 250 mL) x 1000 = 264.2 g/L

Step 2: Calculate the concentration of the diluted solution

Next, we need to calculate the concentration of the diluted solution. We can do this by using the formula for calculating the concentration of a diluted solution.

C = (C_stock x V_stock) / V_diluted = (264.2 g/L x 10.0 mL) / 50.0 mL = 52.84 g/L

Conclusion

In conclusion, a stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations. The process of dilution involves reducing the concentration of a solution by adding a solvent, such as water, to it. By understanding the concept of a stock solution and dilution, we can calculate the concentration of a solution after dilution.

Key Takeaways

  • A stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations.
  • The concentration of a stock solution can be calculated using the formula C = (m / V) x 1000.
  • The process of dilution involves reducing the concentration of a solution by adding a solvent, such as water, to it.
  • The concentration of a diluted solution can be calculated using the formula C = (C_stock x V_stock) / V_diluted.

References

  • "Chemistry: An Atoms First Approach" by Steven S. Zumdahl
  • "General Chemistry: Principles and Modern Applications" by Linus Pauling

Glossary

  • Stock solution: A concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations.
  • Dilution: The process of reducing the concentration of a solution by adding a solvent, such as water, to it.
  • Concentration: The amount of substance per unit volume of solution, expressed in terms of grams per milliliter (g/mL) or moles per liter (M).
    A Stock Solution and Dilution: Understanding the Concept of Concentration - Q&A

In our previous article, we explored the concept of a stock solution and dilution, and how to calculate the concentration of a solution after dilution. In this article, we will answer some frequently asked questions about stock solutions and dilution.

Q: What is a stock solution?

A: A stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations.

Q: Why do we need stock solutions?

A: We need stock solutions because they allow us to prepare solutions of known concentrations quickly and easily. Stock solutions can be used as a starting material for preparing other solutions, such as standard solutions, calibration solutions, and working solutions.

Q: How do I prepare a stock solution?

A: To prepare a stock solution, you need to dissolve a known amount of a substance in a solvent, such as water, to create a solution of a specific concentration. The amount of substance used to prepare the stock solution is typically expressed in terms of its molar mass.

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

A: A stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known 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 calculate the concentration of a stock solution?

A: To calculate the concentration of a stock solution, you need to divide the mass of the substance used to prepare the solution by the volume of the solution.

Q: What is the formula for calculating the concentration of a stock solution?

A: The formula for calculating the concentration of a stock solution is:

C = (m / V) x 1000

where C is the concentration of the solution in g/mL, m is the mass of the substance used to prepare the solution in grams, and V is the volume of the solution in milliliters.

Q: How do I calculate the concentration of a diluted solution?

A: To calculate the concentration of a diluted solution, you need to use the formula:

C = (C_stock x V_stock) / V_diluted

where C is the concentration of the diluted solution in g/mL, C_stock is the concentration of the stock solution in g/mL, V_stock is the volume of the stock solution used to prepare the diluted solution in milliliters, and V_diluted is the volume of the diluted solution in milliliters.

Q: What is the difference between dilution and concentration?

A: Dilution is the process of reducing the concentration of a solution by adding a solvent, such as water, to it. Concentration, on the other hand, is the amount of substance per unit volume of solution, expressed in terms of grams per milliliter (g/mL) or moles per liter (M).

Q: Why is it important to know the concentration of a solution?

A: It is important to know the concentration of a solution because it allows you to prepare solutions of known concentrations quickly and easily. Knowing the concentration of a solution is also important for ensuring the accuracy and reliability of experimental results.

Q: How do I ensure the accuracy and reliability of experimental results?

A: To ensure the accuracy and reliability of experimental results, you need to follow proper laboratory procedures, including using high-quality reagents and equipment, following established protocols, and documenting your results accurately.

Conclusion

In conclusion, a stock solution and dilution are important concepts in chemistry that allow us to prepare solutions of known concentrations quickly and easily. By understanding the concept of a stock solution and dilution, we can calculate the concentration of a solution after dilution and ensure the accuracy and reliability of experimental results.

Key Takeaways

  • A stock solution is a concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations.
  • The concentration of a stock solution can be calculated using the formula C = (m / V) x 1000.
  • The process of dilution involves reducing the concentration of a solution by adding a solvent, such as water, to it.
  • The concentration of a diluted solution can be calculated using the formula C = (C_stock x V_stock) / V_diluted.

References

  • "Chemistry: An Atoms First Approach" by Steven S. Zumdahl
  • "General Chemistry: Principles and Modern Applications" by Linus Pauling

Glossary

  • Stock solution: A concentrated solution of a substance that is used as a starting material for preparing other solutions of known concentrations.
  • Dilution: The process of reducing the concentration of a solution by adding a solvent, such as water, to it.
  • Concentration: The amount of substance per unit volume of solution, expressed in terms of grams per milliliter (g/mL) or moles per liter (M).