1. The Percent Composition of a Compound
10.3
The Percent Composition of a Compound
The ______________ by _____________ of an _______________ in a ______________ is the number of _____________ of the ______________ divided by the mass in ___________ of the ____________, multiplied by 100%.
Potassium chromate (K2CrO4 ) is composed of 40.3% potassium, 26.8% chromium, and 32.9% oxygen. Interpreting Diagrams How does this percent composition differ from the percent composition of potassium dichromate (K2Cr2O7), a compound composed of the same three elements?

2. The Percent Composition of a Compound
10.3
The Percent Composition of a Compound
Potassium chromate (K2CrO4 ) is composed of 40.3% potassium, 26.8% chromium, and 32.9% oxygen. Interpreting Diagrams How does this percent composition differ from the percent composition of potassium dichromate (K2Cr2O7), a compound composed of the same three elements?

3. The Percent Composition of a Compound
10.3
The Percent Composition of a Compound
Percent Composition from Mass Data
The relative amounts of the elements in a compound are expressed as the _____________ _______________________ or the percent by mass of each element in the compound.

4. 10.9

5. for Sample Problem 10.9

6. The Percent Composition of a Compound
10.3
The Percent Composition of a Compound
Percent Composition from the Chemical Formula

7. 10.10

8. for Sample Problem 10.10

9. The Percent Composition of a Compound
10.3
The Percent Composition of a Compound
Percent Composition as a Conversion Factor
You can use percent composition to calculate the number of grams of any element in a specific mass of a compound.

10. The Percent Composition of a Compound
10.3
The Percent Composition of a Compound
Propane (C3H8) is 81.8% carbon and 18% hydrogen. You can calculate the mass of carbon and the mass of hydrogen in an 82.0 g sample of C3H8.

11. The ____________ ___________________ gives the
10.3
Empirical Formulas
The ____________ ___________________ gives the
__________ ___________-__________ ratio of the atoms of the elements in a compound.
The empirical formula of a compound shows the smallest whole-number ratio of the atoms in the compound.

12. 10.3
Empirical Formulas
Ethyne (C2H2) is a gas used in welder’s torches. Styrene (C8H8) is used in making polystyrene.
These two compounds of carbon have the same empirical formula (CH) but different molecular formulas.
Ethyne (C2H2), also called acetylene, is a gas used in welder’s torches. Styrene (C8H8) is used in making polystyrene. These two compounds have the same empirical formula. Calculating What is the empirical formula of ethyne and styrene?

13. 10.11

14. for Sample Problem 10.11

15. 10.3
Molecular Formulas
The molecular formula of a compound is either the same as its experimentally determined empirical formula, or it is a simple whole-number multiple of its empirical formula.

16. 10.3
Molecular Formulas
Methanal, ethanoic acid, and glucose all have the same empirical formula— CH2O.
Methanal (formaldehyde), ethanoic acid (acetic acid), and glucose have the same empirical formula. Applying Concepts How could you easily obtain the molar mass of glucose using the molar mass of methanal?

17. 10.12

18. for Sample Problem 10.12
Sample problem 10-12