Calculating the Number of Moles of Sodium Hydroxide

Oct 13, 2025 by pynkocean.com 19 views

What volume (mL) of $7.48 \times 10^2 \, M$ phosphonic acid can be neutralized with 115 mL of $0.244 \, M$ sodium hydroxide?

Understanding the Problem

To solve this problem, we need to understand the concept of neutralization reactions and the stoichiometry involved. Neutralization reactions occur when an acid reacts with a base to form a salt and water. In this case, phosphonic acid (H3PO3) reacts with sodium hydroxide (NaOH) to form sodium phosphonate (NaH2PO3) and water.

Calculating the Number of Moles of Sodium Hydroxide

First, we need to calculate the number of moles of sodium hydroxide (NaOH) present in 115 mL of 0.244 M solution.

# Import necessary modules
import math
volume_NaOH = 115  # in mL
molarity_NaOH = 0.244  # in M
volume_NaOH_L = volume_NaOH / 1000  # in L
moles_NaOH = molarity_NaOH * volume_NaOH_L  # in mol

Calculating the Number of Moles of Phosphonic Acid Required

Since the reaction between phosphonic acid and sodium hydroxide is a 1:1 reaction, the number of moles of phosphonic acid required to neutralize the sodium hydroxide is equal to the number of moles of sodium hydroxide.

# Calculate the number of moles of phosphonic acid required
moles_H3PO3 = moles_NaOH  # in mol

Calculating the Volume of Phosphonic Acid Required

Now, we need to calculate the volume of phosphonic acid required to provide the calculated number of moles.

# Define variables molarity_H3PO3 = 7.48 * 10**2 # in M volume_H3PO3 = moles_H3PO3 / molarity_H3PO3 # in L

volume_H3PO3_mL = volume_H3PO3 * 1000 # in mL

Rounding the Answer

Finally, we need to round the calculated volume to the nearest whole number.

# Round the answer to the nearest whole number
volume_H3PO3_mL = round(volume_H3PO3_mL)

The Final Answer

The final answer is $\boxed{375}$ mL.

Conclusion

In this problem, we calculated the volume of phosphonic acid required to neutralize 115 mL of 0.244 M sodium hydroxide. We used the concept of neutralization reactions and the stoichiometry involved to solve the problem. The final answer is 375 mL.
Q&A: Neutralization Reactions and Stoichiometry

Q: What is a neutralization reaction?

A: A neutralization reaction is a chemical reaction between an acid and a base that results in the formation of a salt and water. In this reaction, the acid donates a hydrogen ion (H+), while the base accepts the hydrogen ion, resulting in the formation of a salt and water.

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 to produce hydrogen ions (H+), while a weak acid only partially dissociates in water. In this problem, phosphonic acid (H3PO3) is a weak acid.

Q: What is the concept of stoichiometry?

A: Stoichiometry is the study of the quantitative relationships between reactants and products in chemical reactions. In this problem, we used stoichiometry to calculate the number of moles of phosphonic acid required to neutralize the sodium hydroxide.

Q: How do you calculate the number of moles of a substance?

A: To calculate the number of moles of a substance, you need to know its molarity (M) and volume (L). The formula to calculate the number of moles is:

moles = molarity x volume

Q: What is the relationship between the number of moles of an acid and the number of moles of a base in a neutralization reaction?

A: In a neutralization reaction, the number of moles of the acid is equal to the number of moles of the base. This is because the acid and base react in a 1:1 ratio to form a salt and water.

Q: How do you calculate the volume of a substance required to provide a certain number of moles?

A: To calculate the volume of a substance required to provide a certain number of moles, you need to know its molarity (M). The formula to calculate the volume is:

volume = moles / molarity

Q: What is the significance of rounding the answer to the nearest whole number?

A: Rounding the answer to the nearest whole number is important because it provides a more realistic and practical value. In this problem, we rounded the calculated volume to the nearest whole number to provide a more accurate answer.

Q: What are some common mistakes to avoid when solving problems involving neutralization reactions and stoichiometry?

A: Some common mistakes to avoid when solving problems involving neutralization reactions and stoichiometry include:

Not considering the stoichiometry of the reaction
Not calculating the number of moles of the substance correctly
Not rounding the answer to the nearest whole number
Not considering the concentration of the substances

Conclusion

In this Q&A article, we discussed the concept of neutralization reactions and stoichiometry, and provided answers to common questions related to these topics. We also highlighted the importance of considering the stoichiometry of the reaction, calculating the number of moles of the substance correctly, and rounding the answer to the nearest whole number. By following these guidelines, you can solve problems involving neutralization reactions and stoichiometry with confidence.