Calculating the Number of Moles of KCl Required

Oct 13, 2025 by pinkandtrash.com 99 views

Understanding the Problem

To solve this problem, we need to understand the concept of molarity and how it relates to the amount of solute required to prepare a solution of a given concentration. Molarity is defined as the number of moles of solute per liter of solution. In this case, we are given a molarity of 1.50 M and a volume of 0.750 L, and we need to find the amount of KCl (potassium chloride) required to prepare this solution.

Calculating the Number of Moles of KCl Required

The first step in solving this problem is to calculate the number of moles of KCl required to prepare the solution. We can do this by multiplying the molarity of the solution by the volume of the solution in liters.

${1.50 \, \text{M} = \frac{x}{0.750 \, \text{L}}}$

To find the number of moles of KCl required, we can rearrange this equation to solve for x:

${x = 1.50 \, \text{M} \times 0.750 \, \text{L}}$

${x = 1.125 \, \text{mol}}$

Calculating the Mass of KCl Required

Now that we know the number of moles of KCl required, we can calculate the mass of KCl required to prepare the solution. The molar mass of KCl is 74.55 g/mol. We can use this value to calculate the mass of KCl required:

${m = n \times M}$

where m is the mass of KCl required, n is the number of moles of KCl required, and M is the molar mass of KCl.

${m = 1.125 \, \text{mol} \times 74.55 \, \text{g/mol}}$

${m = 83.69 \, \text{g}}$

Conclusion

In conclusion, to prepare 0.750 L of a 1.50 M solution of KCl, we need 83.69 g of KCl.

Additional Information

The molar mass of KCl is 74.55 g/mol.
The molarity of the solution is 1.50 M.
The volume of the solution is 0.750 L.

Step-by-Step Solution

Calculate the number of moles of KCl required to prepare the solution.
Calculate the mass of KCl required to prepare the solution.

Calculations

${x = 1.50 \, \text{M} \times 0.750 \, \text{L}}$
${x = 1.125 \, \text{mol}}$
${m = 1.125 \, \text{mol} \times 74.55 \, \text{g/mol}}$
${m = 83.69 \, \text{g}}$

Final Answer

The final answer is 83.69 g.

Frequently Asked Questions

Q: What is the definition of molarity?

A: Molarity is defined as the number of moles of solute per liter of solution. It is a measure of the concentration of a solution.

Q: How do I calculate the number of moles of KCl required to prepare a 1.50 M solution?

A: To calculate the number of moles of KCl required, you can multiply the molarity of the solution by the volume of the solution in liters. In this case, the molarity is 1.50 M and the volume is 0.750 L.

${x = 1.50 \, \text{M} \times 0.750 \, \text{L}}$

${x = 1.125 \, \text{mol}}$

Q: How do I calculate the mass of KCl required to prepare a 1.50 M solution?

A: To calculate the mass of KCl required, you can multiply the number of moles of KCl required by the molar mass of KCl. The molar mass of KCl is 74.55 g/mol.

${m = n \times M}$

where m is the mass of KCl required, n is the number of moles of KCl required, and M is the molar mass of KCl.

${m = 1.125 \, \text{mol} \times 74.55 \, \text{g/mol}}$

${m = 83.69 \, \text{g}}$

Q: What is the molar mass of KCl?

A: The molar mass of KCl is 74.55 g/mol.

Q: What is the molarity of the solution?

A: The molarity of the solution is 1.50 M.

Q: What is the volume of the solution?

A: The volume of the solution is 0.750 L.

Q: How do I prepare a 1.50 M solution of KCl?

A: To prepare a 1.50 M solution of KCl, you need to calculate the number of moles of KCl required and then calculate the mass of KCl required. Once you have the mass of KCl required, you can weigh out the correct amount of KCl and dissolve it in the appropriate amount of solvent to prepare the solution.

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

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

Not accurately measuring the volume of the solution
Not accurately measuring the mass of the solute
Not dissolving the solute in the correct amount of solvent
Not stirring the solution thoroughly to ensure that the solute is fully dissolved

Conclusion

Preparing a 1.50 M solution of KCl requires careful calculation and attention to detail. By following the steps outlined in this article, you can ensure that you prepare a solution of the correct concentration. Remember to accurately measure the volume of the solution, accurately measure the mass of the solute, dissolve the solute in the correct amount of solvent, and stir the solution thoroughly to ensure that the solute is fully dissolved.

Additional Resources