1. Chemical, Empirical, and Molecular Oh My!
chemistry
Chemical, Empirical, and Molecular Oh My!

2. chemical Formula A way of expressing the number of atoms of a compound
Write the chemical formula of the following:
Sodium chloride ____________
Lithium oxide ____________
Iron (II) bromide ____________
Ammonium sulfide ____________

3. chemical Formula A way of expressing the number of atoms of a compound
Write the chemical formula of the following:
Sodium chloride NaCl
Lithium oxide Li2O
Iron (II) bromide FeBr2
Ammonium sulfide (NH4)2S

4. Types of chemical Formula
Molecular Formula
Identifies the number of each type of atom
Example: Hexane: C6H14
Empirical Formula
Simplest whole number ratio of atoms of each element
Example: Hexane: C3H7
Structural Formula
Shows the structure of the molecule

5. Find the empirical formula
Substance
Molecular Formula
Empirical Formula
Water
H2O
Methane
CH4
Benzene
C6H6
Sulfur S8
Glucose
C6H12O6

6. Find the empirical formula
Substance
Molecular Formula
Empirical Formula
Water
H2O
Methane
CH4
Benzene
C6H6 CH
Sulfur S8 S
Glucose
C6H12O6
CH2O

7. Find the Molecular and Empirical Formula’s

8. Example 1:
A sample of compound contains g Ag, g S, and g O. Determine its empirical formula.

9. Example 1:
A sample of compound contains g Ag, g S, and g O. Determine its empirical formula.

10. Example 1:
A sample of compound contains g Ag, g S, and g O. Determine its empirical formula.

11. Example 1:
A sample of compound contains g Ag, g S, and g O. Determine its empirical formula.

12. Example 1:
A sample of compound contains g Ag, g S, and g O. Determine its empirical formula.
Ans: Ag2SO4

13. Example 2:
A sample of compound contains 18.7% Li, 16.3% C and 65.5% O by mass. Determine its empirical formula.

14. Example 2:
A sample of compound contains 18.7% Li, 16.3% C and 65.5% O by mass. Determine its empirical formula.
Ans: Li2CO3

15. Molecular Formula
To find the Molecular Formula we use the following relationship Where Molar Mass is the mass of the Molecular Formula Where N = the whole number multiple by which the empirical mass is increased

16. Example 3: List 3 possible molecular formula.
A compound has an empirical formula of NH2 and a molar mass of g/mol.
List 3 possible molecular formula.
What is the compound’s molecular formula?

17. Example 3: List 3 possible molecular formulae.
A compound has an empirical formula of NH2 and a molar mass of g/mol.
List 3 possible molecular formulae.
NH2, N2H4, N3H6
What is the compound’s molecular formula?
N2H4

18. Example 4:
A compound containing 40.0% carbon, 6.7% hydrogen and 53.3% oxygen has an atomic mass of g/mol. What is the molecular formula?

19. Example 4:
A compound containing 40.0% carbon, 6.7% hydrogen and 53.3% oxygen has an atomic mass of g/mol. What is the molecular formula?
CH2O

20. Example 4:
A compound containing 40.0% carbon, 6.7% hydrogen and 53.3% oxygen has an atomic mass of g/mol. What is the molecular formula?

21. Molecular Formula: C6H12O6
Example 4:
A compound containing 40.0% carbon, 6.7% hydrogen and 53.3% oxygen has an atomic mass of g/mol. What is the molecular formula?
Molecular Formula: C6H12O6

22. In-Class Work
Complete “Determining empirical formula” and Molecular Formula worksheet. Finish for homework.