Calculating the Number of Moles of Sodium and Water

Oct 13, 2025 by wbrum.org 22 views

Chemical Reactions and Stoichiometry: Calculating the Amount of Hydrogen Gas Formed

Chemical reactions involve the transformation of one or more substances into new substances. These reactions are governed by the laws of conservation of mass and energy, which dictate that matter cannot be created or destroyed in a chemical reaction. In this article, we will explore the concept of stoichiometry, which is the study of the quantitative relationships between reactants and products in chemical reactions. We will use the given chemical equation to calculate the amount of hydrogen gas formed when 2.00 grams of sodium (Na) react with 3.00 grams of water (H2O).

The given chemical equation is:

2 Na + 2 H2O → 2 NaOH + H2

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

Calculating the Number of Moles of Sodium and Water

To calculate the number of moles of sodium and water, we need to know their molar masses. The molar mass of sodium (Na) is 22.99 g/mol, and the molar mass of water (H2O) is 18.02 g/mol.

Number of moles of sodium (Na) = mass of sodium / molar mass of sodium = 2.00 g / 22.99 g/mol = 0.0871 mol

Number of moles of water (H2O) = mass of water / molar mass of water = 3.00 g / 18.02 g/mol = 0.1665 mol

Determining the Limiting Reactant

To determine the limiting reactant, we need to compare the mole ratio of sodium to water with the mole ratio in the balanced chemical equation.

Mole ratio of sodium to water in the balanced equation = 2:2 = 1:1

Mole ratio of sodium to water in the given reaction = 0.0871 mol: 0.1665 mol = 1:1.9

Since the mole ratio of sodium to water in the given reaction is greater than the mole ratio in the balanced equation, water is the limiting reactant.

Calculating the Number of Moles of Hydrogen Gas Formed

Since water is the limiting reactant, we can use the number of moles of water to calculate the number of moles of hydrogen gas formed.

Number of moles of hydrogen gas formed = number of moles of water / 2 = 0.1665 mol / 2 = 0.08325 mol

Calculating the Mass of Hydrogen Gas Formed

To calculate the mass of hydrogen gas formed, we need to know the molar mass of hydrogen gas (H2), which is 2.02 g/mol.

Mass of hydrogen gas formed = number of moles of hydrogen gas formed x molar mass of hydrogen gas = 0.08325 mol x 2.02 g/mol = 0.1685 g

In this article, we used the given chemical equation to calculate the amount of hydrogen gas formed when 2.00 grams of sodium react with 3.00 grams of water. We determined that water is the limiting reactant and used the number of moles of water to calculate the number of moles of hydrogen gas formed. Finally, we calculated the mass of hydrogen gas formed using the molar mass of hydrogen gas.

The correct answer is B. 0.168 grams.
Chemical Reactions and Stoichiometry: Q&A

In our previous article, we explored the concept of stoichiometry and used the given chemical equation to calculate the amount of hydrogen gas formed when 2.00 grams of sodium react with 3.00 grams of water. In this article, we will answer some frequently asked questions related to chemical reactions and stoichiometry.

Q: What is stoichiometry?

A: Stoichiometry is the study of the quantitative relationships between reactants and products in chemical reactions. It involves calculating the amounts of reactants and products in a chemical reaction.

Q: What is the difference between a balanced equation and an unbalanced equation?

A: A balanced equation is a chemical equation in which the number of atoms of each element is the same on both the reactant and product sides. An unbalanced equation is a chemical equation in which the number of atoms of each element is not the same on both the reactant and product sides.

Q: How do you determine the limiting reactant in a chemical reaction?

A: To determine the limiting reactant, you need to compare the mole ratio of the reactants with the mole ratio in the balanced chemical equation. The reactant with the smaller mole ratio is the limiting reactant.

Q: What is the mole ratio of sodium to water in the balanced chemical equation?

A: The mole ratio of sodium to water in the balanced chemical equation is 1:1.

Q: What is the mole ratio of sodium to water in the given reaction?

A: The mole ratio of sodium to water in the given reaction is 1:1.9.

Q: Why is water the limiting reactant in the given reaction?

A: Water is the limiting reactant in the given reaction because the mole ratio of sodium to water in the given reaction is greater than the mole ratio in the balanced equation.

Q: How do you calculate the number of moles of hydrogen gas formed in a chemical reaction?

A: To calculate the number of moles of hydrogen gas formed, you need to know the number of moles of the limiting reactant and the mole ratio of the limiting reactant to hydrogen gas in the balanced chemical equation.

Q: How do you calculate the mass of hydrogen gas formed in a chemical reaction?

A: To calculate the mass of hydrogen gas formed, you need to know the number of moles of hydrogen gas formed and the molar mass of hydrogen gas.

Q: What is the molar mass of hydrogen gas (H2)?

A: The molar mass of hydrogen gas (H2) is 2.02 g/mol.

Q: What is the mass of hydrogen gas formed when 2.00 grams of sodium react with 3.00 grams of water?

A: The mass of hydrogen gas formed when 2.00 grams of sodium react with 3.00 grams of water is 0.1685 g.

In this article, we answered some frequently asked questions related to chemical reactions and stoichiometry. We hope that this article has provided you with a better understanding of the concepts of stoichiometry and chemical reactions.

Stoichiometry is the study of the quantitative relationships between reactants and products in chemical reactions.
A balanced equation is a chemical equation in which the number of atoms of each element is the same on both the reactant and product sides.
The limiting reactant is the reactant with the smaller mole ratio in a chemical reaction.
The mole ratio of sodium to water in the balanced chemical equation is 1:1.
The mole ratio of sodium to water in the given reaction is 1:1.9.
Water is the limiting reactant in the given reaction.
The number of moles of hydrogen gas formed can be calculated by knowing the number of moles of the limiting reactant and the mole ratio of the limiting reactant to hydrogen gas in the balanced chemical equation.
The mass of hydrogen gas formed can be calculated by knowing the number of moles of hydrogen gas formed and the molar mass of hydrogen gas.