Calculating the Volume of Sodium Hydroxide Required

Oct 13, 2025 by pynkocean.com 114 views

Introduction

Titration is a laboratory technique used to determine the concentration of a substance in a solution. It involves the reaction of a known concentration of one substance with an unknown concentration of another substance. In this article, we will discuss the titration of phosphoric acid with sodium hydroxide and calculate the volume of sodium hydroxide required to titrate a given volume of phosphoric acid.

Chemical Reaction

The chemical reaction between phosphoric acid (H3PO4) and sodium hydroxide (NaOH) is as follows:

H3PO4 + 3NaOH → Na3PO4 + 3H2O

This reaction is a neutralization reaction, where the acid (H3PO4) reacts with the base (NaOH) to form a salt (Na3PO4) and water.

Calculating the Volume of Sodium Hydroxide Required

To calculate the volume of sodium hydroxide required to titrate a given volume of phosphoric acid, we need to use the concept of stoichiometry. Stoichiometry is the study of the quantitative relationships between reactants and products in chemical reactions.

The balanced chemical equation for the reaction between phosphoric acid and sodium hydroxide is:

H3PO4 + 3NaOH → Na3PO4 + 3H2O

From the balanced equation, we can see that 1 mole of phosphoric acid reacts with 3 moles of sodium hydroxide.

The molarity of the phosphoric acid solution is 0.2 M, which means that there are 0.2 moles of phosphoric acid per liter of solution. The volume of the phosphoric acid solution is 50 mL, which is equivalent to 0.05 L.

The number of moles of phosphoric acid in 50 mL of solution is:

moles = molarity x volume (in L) = 0.2 M x 0.05 L = 0.01 moles

Since 1 mole of phosphoric acid reacts with 3 moles of sodium hydroxide, the number of moles of sodium hydroxide required to titrate 50 mL of phosphoric acid is:

moles of NaOH = 3 x moles of H3PO4 = 3 x 0.01 moles = 0.03 moles

The molarity of the sodium hydroxide solution is 0.3 M, which means that there are 0.3 moles of sodium hydroxide per liter of solution. To find the volume of sodium hydroxide solution required to provide 0.03 moles of sodium hydroxide, we can use the formula:

volume = moles / molarity = 0.03 moles / 0.3 M = 0.1 L

Since 1 L is equivalent to 1000 mL, the volume of sodium hydroxide solution required to titrate 50 mL of phosphoric acid is:

volume = 0.1 L x 1000 mL/L = 100 mL

However, this is not the only option. We can also express the volume of sodium hydroxide solution required in milliliters as a fraction of the total volume of the solution. Since the volume of the phosphoric acid solution is 50 mL, the volume of sodium hydroxide solution required is:

volume = 100 mL / 50 mL = 2

This means that the volume of sodium hydroxide solution required is 2 times the volume of the phosphoric acid solution.

Conclusion

In this article, we have discussed the titration of phosphoric acid with sodium hydroxide and calculated the volume of sodium hydroxide required to titrate a given volume of phosphoric acid. We have used the concept of stoichiometry to determine the number of moles of sodium hydroxide required and then calculated the volume of sodium hydroxide solution required to provide that number of moles.

The volume of sodium hydroxide solution required to titrate 50 mL of 0.2 M phosphoric acid is 100 mL. However, we can also express the volume of sodium hydroxide solution required as a fraction of the total volume of the solution, which is 2 times the volume of the phosphoric acid solution.

Answer

The correct answer is A. 75 mL

Introduction

In our previous article, we discussed the titration of phosphoric acid with sodium hydroxide and calculated the volume of sodium hydroxide required to titrate a given volume of phosphoric acid. In this article, we will answer some frequently asked questions related to the titration of phosphoric acid with sodium hydroxide.

Q: What is the chemical reaction between phosphoric acid and sodium hydroxide?

A: The chemical reaction between phosphoric acid (H3PO4) and sodium hydroxide (NaOH) is as follows:

H3PO4 + 3NaOH → Na3PO4 + 3H2O

This reaction is a neutralization reaction, where the acid (H3PO4) reacts with the base (NaOH) to form a salt (Na3PO4) and water.

Q: What is the molarity of the phosphoric acid solution?

A: The molarity of the phosphoric acid solution is 0.2 M, which means that there are 0.2 moles of phosphoric acid per liter of solution.

Q: What is the volume of the phosphoric acid solution?

A: The volume of the phosphoric acid solution is 50 mL, which is equivalent to 0.05 L.

Q: How many moles of phosphoric acid are in 50 mL of solution?

A: The number of moles of phosphoric acid in 50 mL of solution is:

moles = molarity x volume (in L) = 0.2 M x 0.05 L = 0.01 moles

Q: How many moles of sodium hydroxide are required to titrate 50 mL of phosphoric acid?

A: Since 1 mole of phosphoric acid reacts with 3 moles of sodium hydroxide, the number of moles of sodium hydroxide required to titrate 50 mL of phosphoric acid is:

moles of NaOH = 3 x moles of H3PO4 = 3 x 0.01 moles = 0.03 moles

Q: What is the molarity of the sodium hydroxide solution?

A: The molarity of the sodium hydroxide solution is 0.3 M, which means that there are 0.3 moles of sodium hydroxide per liter of solution.

Q: What is the volume of sodium hydroxide solution required to provide 0.03 moles of sodium hydroxide?

A: The volume of sodium hydroxide solution required to provide 0.03 moles of sodium hydroxide is:

volume = moles / molarity = 0.03 moles / 0.3 M = 0.1 L

Q: What is the volume of sodium hydroxide solution required to titrate 50 mL of phosphoric acid?

A: The volume of sodium hydroxide solution required to titrate 50 mL of phosphoric acid is:

volume = 0.1 L x 1000 mL/L = 100 mL

Q: Can the volume of sodium hydroxide solution required be expressed as a fraction of the total volume of the solution?

A: Yes, the volume of sodium hydroxide solution required can be expressed as a fraction of the total volume of the solution. Since the volume of the phosphoric acid solution is 50 mL, the volume of sodium hydroxide solution required is:

volume = 100 mL / 50 mL = 2

This means that the volume of sodium hydroxide solution required is 2 times the volume of the phosphoric acid solution.

Conclusion

In this article, we have answered some frequently asked questions related to the titration of phosphoric acid with sodium hydroxide. We have discussed the chemical reaction between phosphoric acid and sodium hydroxide, the molarity and volume of the phosphoric acid solution, the number of moles of phosphoric acid and sodium hydroxide required, and the volume of sodium hydroxide solution required to titrate 50 mL of phosphoric acid.

Answer

The correct answer is A. 75 mL