1. Section 7.3 Percent Composition of a Compound Here’s were the math starts to get fun!!!

2. Calculating the Percent Composition of a Compound 1.The relative amounts of each element in a compound are expressed as the percent composition, or the percent by mass of each element in a compound. Example:

3. Calculating the Percent Composition of a Compound 1.The relative amounts of each element in a compound are expressed as the percent composition, or the percent by mass of each element in a compound. Example: An 8.20 gram piece of magnesium combines completely with 5.40 grams of oxygen gas to form a compound. What is the percent composition of this compound?

4. Calculating the Percent Composition of a Compound 8.20g + 5.40g  13.60g Mg O  MgO What is the percent composition of this compound?

5. Calculating the Percent Composition of a Compound 8.20g + 5.40g  13.60g Mg O  MgO What is the percent composition of this compound? For magnesium, Mass of Mg  Total mass of compound 

6. Calculating the Percent Composition of a Compound 8.20g + 5.40g  13.60g Mg O  MgO What is the percent composition of this compound? For magnesium, Mass of Mg  8.2g = Total mass of compound  13.6

7. Calculating the Percent Composition of a Compound 8.20g + 5.40g  13.60g Mg O  MgO What is the percent composition of this compound? For magnesium, Mass of Mg  8.2g = 60.3% Total mass of compound  13.6

8. Calculating the Percent Composition of a Compound 8.20g + 5.40g  13.60g Mg O  MgO What is the percent composition of this compound? For magnesium, Mass of Mg  8.2g = 60.3% Total mass of compound  13.6 So, for the Oxygen, 100% - 60.3% = 39.7%

9. Calculating the Percent Composition of a Compound Sample Calculations 1. 9.30 grams of magnesium combine completely with 3.48 grams of nitrogen gas to form a compound. What is the percent composition of this compound?

10. Calculating the Percent Composition of a Compound Sample Calculations 9.30g + 3.48g  12.78g Mg + N 2 (g)  compound