Calculating the Amount of NaBr Needed

Oct 13, 2025 by wbrum.org 57 views

**How Many mL of a 2.0M NaBr Solution Are Needed to Make 200.0 mL of 0.50M NaBr?**

Understanding the Problem

To solve this problem, we need to understand the concept of molarity and how it relates to the amount of substance needed to make a solution of a specific concentration.

What is Molarity?

Molarity is a measure of the concentration of a solution, expressed as the number of moles of solute per liter of solution. It is denoted by the symbol M and is calculated as follows:

Molarity (M) = Number of moles of solute / Volume of solution (in liters)

Calculating the Amount of NaBr Needed

We are given a 2.0M NaBr solution and want to make 200.0 mL of 0.50M NaBr. To calculate the amount of NaBr needed, we can use the following steps:

Calculate the number of moles of NaBr needed to make 200.0 mL of 0.50M NaBr:

Number of moles = Molarity x Volume (in liters) = 0.50 M x 0.200 L = 0.10 mol

Calculate the volume of the 2.0M NaBr solution needed to provide 0.10 mol of NaBr:

Molarity (2.0M) = Number of moles / Volume (in liters) 0.10 mol = 2.0 M x Volume (in liters) Volume (in liters) = 0.10 mol / 2.0 M = 0.05 L = 50 mL

Conclusion

Therefore, to make 200.0 mL of 0.50M NaBr, we need 50 mL of a 2.0M NaBr solution.

Q&A

Q: What is the definition of a solution?

A: A solution is a homogeneous mixture of 2 or more substances.

Q: What is molarity?

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

Q: How is molarity calculated?

A: Molarity is calculated as follows: Molarity (M) = Number of moles of solute / Volume of solution (in liters)

Q: How do I calculate the amount of substance needed to make a solution of a specific concentration?

A: To calculate the amount of substance needed, you can use the following steps:

Calculate the number of moles of solute needed to make the desired volume of solution.
Calculate the volume of the solution needed to provide the desired number of moles of solute.

Q: What is the difference between a solution and a mixture?

A: A solution is a homogeneous mixture of 2 or more substances, while a mixture is a heterogeneous mixture of 2 or more substances.

Q: How do I determine the concentration of a solution?

A: To determine the concentration of a solution, you can use the following methods:

Measure the volume of the solution and the number of moles of solute.
Calculate the molarity of the solution using the formula: Molarity (M) = Number of moles of solute / Volume of solution (in liters)

Q: What is the importance of molarity in chemistry?

A: Molarity is an important concept in chemistry because it allows us to calculate the amount of substance needed to make a solution of a specific concentration, which is essential in many chemical reactions and processes.

Q: How do I convert between different units of concentration?

A: To convert between different units of concentration, you can use the following conversion factors:

Molarity (M) = Number of moles of solute / Volume of solution (in liters)
Molality (m) = Number of moles of solute / Mass of solvent (in kg)
Percentage concentration (%) = (Number of moles of solute / Total number of moles) x 100

Q: What are some common applications of molarity in chemistry?

A: Molarity is used in many chemical reactions and processes, including:

Titration: Molarity is used to calculate the amount of substance needed to react with a known amount of substance.
Dilution: Molarity is used to calculate the amount of substance needed to dilute a solution to a specific concentration.
Concentration: Molarity is used to calculate the concentration of a solution.

Q: How do I calculate the volume of a solution needed to provide a specific amount of substance?

A: To calculate the volume of a solution needed, you can use the following steps:

Calculate the number of moles of solute needed.
Calculate the molarity of the solution using the formula: Molarity (M) = Number of moles of solute / Volume of solution (in liters)
Rearrange the formula to solve for volume: Volume (in liters) = Number of moles of solute / Molarity (M)

Q: What is the difference between a strong acid and a weak acid?

A: A strong acid is an acid that completely dissociates in water, while a weak acid is an acid that only partially dissociates in water.

Q: How do I calculate the pH of a solution?

A: To calculate the pH of a solution, you can use the following formula:

pH = -log[H+]

where [H+] is the concentration of hydrogen ions in the solution.

Q: What is the importance of pH in chemistry?

A: pH is an important concept in chemistry because it allows us to calculate the acidity or basicity of a solution, which is essential in many chemical reactions and processes.

Q: How do I convert between different units of pH?

A: To convert between different units of pH, you can use the following conversion factors:

pH = -log[H+]
pOH = -log[OH-]
pH + pOH = 14

Q: What are some common applications of pH in chemistry?

A: pH is used in many chemical reactions and processes, including:

Acid-base titration: pH is used to calculate the amount of substance needed to react with a known amount of substance.
Buffer solutions: pH is used to calculate the concentration of a buffer solution.
Enzyme activity: pH is used to calculate the activity of enzymes.

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

A: To calculate the concentration of a solution, you can use the following methods:

Measure the volume of the solution and the number of moles of solute.
Calculate the molarity of the solution using the formula: Molarity (M) = Number of moles of solute / Volume of solution (in liters)

Q: What is the difference between a solution and a mixture?

A: A solution is a homogeneous mixture of 2 or more substances, while a mixture is a heterogeneous mixture of 2 or more substances.

Q: How do I determine the concentration of a solution?

A: To determine the concentration of a solution, you can use the following methods:

Measure the volume of the solution and the number of moles of solute.
Calculate the molarity of the solution using the formula: Molarity (M) = Number of moles of solute / Volume of solution (in liters)

Q: What is the importance of concentration in chemistry?

A: Concentration is an important concept in chemistry because it allows us to calculate the amount of substance needed to make a solution of a specific concentration, which is essential in many chemical reactions and processes.

Q: How do I convert between different units of concentration?

A: To convert between different units of concentration, you can use the following conversion factors:

Molarity (M) = Number of moles of solute / Volume of solution (in liters)
Molality (m) = Number of moles of solute / Mass of solvent (in kg)
Percentage concentration (%) = (Number of moles of solute / Total number of moles) x 100

Q: What are some common applications of concentration in chemistry?

A: Concentration is used in many chemical reactions and processes, including:

Titration: Concentration is used to calculate the amount of substance needed to react with a known amount of substance.
Dilution: Concentration is used to calculate the amount of substance needed to dilute a solution to a specific concentration.
Concentration: Concentration is used to calculate the concentration of a solution.