1. PERCENT COMPOSITION

2. WHAT IS PERCENT COMPOSITION BY MASS? a quantitative measure of what a compound or mixture is made of it tells us how much of each substance is in the compound or mixture it uses the mass of each substance and the total mass of the compound or mixture to arrive at a percentage for each substance

3. YOU TUBE http://www.google.com/url?sa=t&rct=j&q=percent% 20composition&source=web&cd=3&cad=rja&uact=8 &ved=0CCwQtwIwAg&url=http%3A%2F%2Fwww.you tube.com%2Fwatch%3Fv%3DlywmGCfIUIA&ei=Zv6rV PiSCu7IsAT-- YLwBQ&usg=AFQjCNEJiUWALuFjmW27Lx4ACH7QmB qOQQ&bvm=bv.82001339,d.cWc

4. PERCENT COMPOSITION  Sometimes it’s useful to know the composition of a compound in terms of what percentage of the total is each element  Percent  “Parts per 100”  The number of specific items per a group of 100 items  50% of $100 is $50 (50 items/100 total items)

5. Percent Example You have 4 oranges and 5 apples. What percent of the total is oranges? You have 4 oranges and 5 apples. What percent of the total is oranges? In “parts per 100” In “parts per 100”

6. Percent Composition It is the percent by mass of each element in a compound It is the percent by mass of each element in a compound Can be determined Can be determined By its chemical formula By its chemical formula Molar masses of the elements that compose the compound Molar masses of the elements that compose the compound The percent of each element contributes to the mass of the compound The percent of each element contributes to the mass of the compound

7. Calculating Percent Composition Example What is the percent composition of each element in NH 4 OH? What is the percent composition of each element in NH 4 OH? Determine the contribution of each element Molar mass