Calculating the Total Mass of Water Formed in a Chemical Reaction

Oct 13, 2025 by wbrum.org 113 views

Calculating the Total Mass of Water Formed in a Chemical Reaction

Understanding the Balanced Equation

The given balanced equation represents a reaction between hydrogen gas (H2) and oxygen gas (O2) to form water (H2O). The balanced equation is:

2 H2 + O2 → 2 H2O

This equation indicates that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water.

Determining the Molar Mass of Reactants and Products

To calculate the total mass of water formed, we need to determine the molar mass of the reactants and products. The molar mass of hydrogen (H2) is 2 g/mol, and the molar mass of oxygen (O2) is 32 g/mol. The molar mass of water (H2O) is 18 g/mol.

Calculating the Number of Moles of Reactants

We are given 8 grams of hydrogen and 64 grams of oxygen. We can calculate the number of moles of each reactant using the formula:

moles = mass / molar mass

For hydrogen:

moles H2 = 8 g / 2 g/mol = 4 mol

For oxygen:

moles O2 = 64 g / 32 g/mol = 2 mol

Determining the Limiting Reactant

Since the balanced equation indicates that 2 moles of hydrogen react with 1 mole of oxygen, we can see that the number of moles of hydrogen (4 mol) is twice the number of moles of oxygen (2 mol). This means that oxygen is the limiting reactant, and all of the oxygen will be consumed in the reaction.

Calculating the Total Mass of Water Formed

Since oxygen is the limiting reactant, we can calculate the total mass of water formed using the number of moles of oxygen. The balanced equation indicates that 1 mole of oxygen produces 2 moles of water. Therefore, 2 moles of oxygen will produce 4 moles of water.

The molar mass of water is 18 g/mol, so the total mass of water formed is:

mass H2O = moles H2O x molar mass H2O = 4 mol x 18 g/mol = 72 g

Therefore, the total mass of water formed when 8 grams of hydrogen reacts completely with 64 grams of oxygen is 72 grams.

Conclusion

In this article, we have calculated the total mass of water formed in a chemical reaction between hydrogen and oxygen. We have determined the molar mass of the reactants and products, calculated the number of moles of each reactant, and identified the limiting reactant. Finally, we have calculated the total mass of water formed using the number of moles of the limiting reactant. The result is 72 grams of water.

References

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

Discussion Questions

What is the balanced equation for the reaction between hydrogen and oxygen?
What is the molar mass of hydrogen, oxygen, and water?
How many moles of hydrogen and oxygen are present in 8 grams of hydrogen and 64 grams of oxygen?
Which reactant is the limiting reactant in this reaction?
What is the total mass of water formed when 8 grams of hydrogen reacts completely with 64 grams of oxygen?
Q&A: Calculating the Total Mass of Water Formed in a Chemical Reaction

Q: What is the balanced equation for the reaction between hydrogen and oxygen?

A: The balanced equation for the reaction between hydrogen and oxygen is:

2 H2 + O2 → 2 H2O

Q: What is the molar mass of hydrogen, oxygen, and water?

A: The molar mass of hydrogen (H2) is 2 g/mol, the molar mass of oxygen (O2) is 32 g/mol, and the molar mass of water (H2O) is 18 g/mol.

Q: How many moles of hydrogen and oxygen are present in 8 grams of hydrogen and 64 grams of oxygen?

A: To calculate the number of moles of each reactant, we can use the formula:

moles = mass / molar mass

For hydrogen:

moles H2 = 8 g / 2 g/mol = 4 mol

For oxygen:

moles O2 = 64 g / 32 g/mol = 2 mol

Q: Which reactant is the limiting reactant in this reaction?

A: Since the balanced equation indicates that 2 moles of hydrogen react with 1 mole of oxygen, we can see that the number of moles of hydrogen (4 mol) is twice the number of moles of oxygen (2 mol). This means that oxygen is the limiting reactant, and all of the oxygen will be consumed in the reaction.

Q: What is the total mass of water formed when 8 grams of hydrogen reacts completely with 64 grams of oxygen?

A: Since oxygen is the limiting reactant, we can calculate the total mass of water formed using the number of moles of oxygen. The balanced equation indicates that 1 mole of oxygen produces 2 moles of water. Therefore, 2 moles of oxygen will produce 4 moles of water.

The molar mass of water is 18 g/mol, so the total mass of water formed is:

mass H2O = moles H2O x molar mass H2O = 4 mol x 18 g/mol = 72 g

Q: What is the significance of the limiting reactant in a chemical reaction?

A: The limiting reactant is the reactant that is consumed first in a chemical reaction. In this case, oxygen is the limiting reactant, and all of the oxygen will be consumed in the reaction. The limiting reactant determines the amount of product that can be formed.

Q: How can we determine the limiting reactant in a chemical reaction?

A: To determine the limiting reactant, we can compare the mole ratio of the reactants to the mole ratio indicated by the balanced equation. If the mole ratio of the reactants is less than the mole ratio indicated by the balanced equation, then the reactant with the lower mole ratio is the limiting reactant.

Q: What is the relationship between the mole ratio of reactants and the mole ratio of products in a chemical reaction?

A: The mole ratio of reactants is equal to the mole ratio of products in a chemical reaction. This means that if the mole ratio of reactants is 2:1, then the mole ratio of products will also be 2:1.

Q: How can we use the mole ratio of reactants to calculate the total mass of product formed in a chemical reaction?

A: To calculate the total mass of product formed, we can use the mole ratio of reactants to determine the number of moles of product formed. We can then multiply the number of moles of product by the molar mass of the product to determine the total mass of product formed.

Q: What is the importance of calculating the total mass of product formed in a chemical reaction?

A: Calculating the total mass of product formed is important because it allows us to determine the amount of product that can be formed in a chemical reaction. This information is useful in a variety of applications, including industrial processes and laboratory experiments.