Understanding Percent Composition

Percent composition is a critical concept in chemistry that helps determine the proportion of each element in a compound. This information is valuable for various applications, including stoichiometry, chemical analysis, and formulation of compounds. In this article, we will explore three diverse examples of calculating the percent composition of a compound.

Example 1: Determining the Percent Composition of Water (H₂O)

Water is essential for life, and its molecular formula is H₂O, indicating it consists of two hydrogen atoms and one oxygen atom. Understanding its composition can be useful in various fields, including environmental science and biology.

To find the percent composition of water, we first need to determine the molar mass of each element:

• Hydrogen (H): 1.01 g/mol (2 atoms = 2.02 g/mol)
• Oxygen (O): 16.00 g/mol (1 atom = 16.00 g/mol)

Next, we calculate the total molar mass of water:

• Total molar mass of H₂O = 2.02 g/mol + 16.00 g/mol = 18.02 g/mol

Now, we can calculate the percent composition:

• Percent composition of Hydrogen = (2.02 g/mol / 18.02 g/mol) × 100 = 11.21%
• Percent composition of Oxygen = (16.00 g/mol / 18.02 g/mol) × 100 = 88.79%

In summary, the percent composition of water is approximately 11.21% hydrogen and 88.79% oxygen. This calculation is vital in fields like chemistry and environmental science, where the properties of water play a crucial role.

Example 2: Analyzing the Percent Composition of Sodium Chloride (NaCl)

Sodium chloride, commonly known as table salt, is a compound made of sodium and chlorine. Understanding its percent composition is important for culinary applications and food science.

First, we determine the molar mass of sodium chloride:

• Sodium (Na): 22.99 g/mol (1 atom = 22.99 g/mol)
• Chlorine (Cl): 35.45 g/mol (1 atom = 35.45 g/mol)

Now, we calculate the total molar mass of NaCl:

• Total molar mass of NaCl = 22.99 g/mol + 35.45 g/mol = 58.44 g/mol

Next, we calculate the percent composition:

• Percent composition of Sodium = (22.99 g/mol / 58.44 g/mol) × 100 = 39.34%
• Percent composition of Chlorine = (35.45 g/mol / 58.44 g/mol) × 100 = 60.66%

Thus, the percent composition of sodium chloride is approximately 39.34% sodium and 60.66% chlorine. This information is particularly useful in industries related to food and chemical manufacturing.

Example 3: Exploring the Percent Composition of Glucose (C₆H₁₂O₆)

Glucose is a simple sugar that is an essential energy source for living organisms. Its molecular formula is C₆H₁₂O₆, and understanding its composition is vital for nutritional science and biochemistry.

To calculate the percent composition, we first find the molar mass of glucose:

• Carbon (C): 12.01 g/mol (6 atoms = 72.06 g/mol)
• Hydrogen (H): 1.01 g/mol (12 atoms = 12.12 g/mol)
• Oxygen (O): 16.00 g/mol (6 atoms = 96.00 g/mol)

Now, we calculate the total molar mass of C₆H₁₂O₆:

• Total molar mass of C₆H₁₂O₆ = 72.06 g/mol + 12.12 g/mol + 96.00 g/mol = 180.18 g/mol

Now we can determine the percent composition:

• Percent composition of Carbon = (72.06 g/mol / 180.18 g/mol) × 100 = 40.00%
• Percent composition of Hydrogen = (12.12 g/mol / 180.18 g/mol) × 100 = 6.73%
• Percent composition of Oxygen = (96.00 g/mol / 180.18 g/mol) × 100 = 53.27%

In conclusion, the percent composition of glucose is approximately 40.00% carbon, 6.73% hydrogen, and 53.27% oxygen. This information is essential in fields like nutrition and metabolic studies, where glucose’s role in energy production is critical.

These examples of calculating percent composition of a compound demonstrate the process and utility of understanding the proportions of elements in various substances, providing a foundation for further exploration in chemistry.