Understanding Molar Mass and Stoichiometry: How Many Moles of CO2 Contain 16 grams of Oxygen?

Introduction

In chemistry, the concept of 'moles' represents a fundamental unit of measurement. Just as a dozen is a number, a mole in chemistry is a vast number of particles, specifically 6.022×1023 (Avogadro's number). This article delves into the concept of molar mass and stoichiometry, focusing on the calculation of moles of CO2 that contain 16 grams of oxygen. Through step-by-step examples, we'll explore the underlying principles and applications of these concepts.

Molar Mass and Oxygen

The molar mass of a substance is the mass of one mole of that substance. For oxygen (O), the molar mass is approximately 16 g/mol. This means that one mole of oxygen has a mass of 16 grams.

Calculating Moles of Oxygen

Given that 16 grams of oxygen (O) corresponds to one mole of oxygen, we can calculate the number of moles of oxygen in the sample provided:

Moles of O mass of O / molar mass of O 16 g / 16 g/mol 1 mol of O.

Stoichiometry and CO

Next, we need to determine how many moles of CO are equivalent to 1 mole of oxygen. Note that each molecule of CO contains 2 atoms of oxygen:

Moles of CO moles of O / 2 1 mol O / 2 0.5 mol of CO.

Therefore, 0.5 moles of CO contain 16 grams of oxygen.

Molecular Weight of CO2

The molecular weight of carbon dioxide (CO2) is calculated by adding the atomic weights of its constituent elements. The atomic mass of carbon (C) is approximately 12 u, and the atomic mass of oxygen (O) is approximately 16 u. Since there are two oxygen atoms in CO2, the molecular weight is:

Molecular Weight of CO2 12 u (C) 2 × 16 u (O) 12 32 44 u.

Calculating Moles of CO2

Given that 32 grams of oxygen (O2) are required to form one mole of CO2, we can determine the moles of CO2 that can be formed with 16 grams of oxygen:

32 g of O2 corresponds to 1 mole of CO2.

16 g of O2 corresponds to 1 × 16 g / 32 g 0.5 moles of CO2.

Generalizing the Concept

The principle can be extended to any compound. For example, consider sulfur dioxide (SO2):

1 molecule of CO2 contains 2 atoms of oxygen, so 1 mole of CO2 contains 2 moles of oxygen atoms. Therefore, 32 grams (1 mole) of oxygen are required for 1 mole of CO2. To find the number of moles of CO2 that contain 16 grams of oxygen:

No. of moles of CO2 containing 16 g of oxygen 1 mole × (16 g / 32 g) 0.5 mole.

Conclusion

Understanding the relationship between molar mass and the number of moles is crucial in chemistry. This article has demonstrated how to calculate moles of CO2 that contain a specific amount of oxygen. By applying the principles of stoichiometry, students can solve similar problems involving various compounds and their components.