section 7.3 percent composition of a compound here’s were the math starts to get fun!!!

Section 7.3Percent Composition of a

Compound

Here’s were the math starts to get fun!!!

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:


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?


• 8.20g + 5.40g 13.60g

Mg O MgO

What is the percent composition of this compound?


• 8.20g + 5.40g 13.60g

Mg O MgO


For magnesium,

Mass of Mg

Total mass of compound


• 8.20g + 5.40g 13.60g

Mg O MgO


For magnesium,

Mass of Mg 8.2g =

Total mass of compound 13.6


• 8.20g + 5.40g 13.60g

Mg O MgO


For magnesium,

Mass of Mg 8.2g =

60.3%Total mass of compound 13.6


• 8.20g + 5.40g 13.60g

Mg O MgO


For magnesium,

Mass of Mg 8.2g = 60.3%Total mass of compound 13.6

So, for the Oxygen, 100% - 60.3% = 39.7%


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?


Sample Calculations

9.30g + 3.48g 12.78g

Mg + N2 (g) compound

section 7.3 percent composition of a compound here’s were the math starts to get fun!!!

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