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Formulae

Formulae. Chemical, Empirical, and Molecular Formula Oh My!. chemical Formulae. 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 ____________

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Formulae

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  1. Formulae Chemical, Empirical, and Molecular Formula Oh My!

  2. chemical Formulae • 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 sulphide ____________

  3. chemical Formulae • 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 sulphide (NH4)2S

  4. Types of chemical Formulae • 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

  6. Find the empirical formula

  7. Find the Molecular and Empirical Formula’s

  8. Example 1: • A sample of compound contains 5.723 g Ag, 0.852 g S, and 1.695 g O. Determine its empirical formula.

  9. Example 1: • A sample of compound contains 5.723 g Ag, 0.852 g S, and 1.695 g O. Determine its empirical formula.

  10. Example 1: • A sample of compound contains 5.723 g Ag, 0.852 g S, and 1.695 g O. Determine its empirical formula.

  11. Example 1: • A sample of compound contains 5.723 g Ag, 0.852 g S, and 1.695 g O. Determine its empirical formula.

  12. Example 1: • A sample of compound contains 5.723 g Ag, 0.852 g S, and 1.695 g O. Determine its empirical formula. Ans: Ag2SO4

  13. Example 2: • A sample of compound contains 18.7% Li, 16.3% C and 65.0% O by mass. Determine its empirical formula.

  14. Example 2: • A sample of compound contains 18.7% Li, 16.3% C and 65.0% 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: • A compound has an empirical formula of NH2 and a molar mass of 32.1 g/mol. • List 3 possible molecular formulae. • What is the compound’s molecular formula?

  17. Example 3: • A compound has an empirical formula of NH2 and a molar mass of 32.1 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 molar mass of 180.2 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 molar mass of 180.2 g/mol. What is the molecular formula?

  20. Example 4: • A compound containing 40.0% carbon, 6.7% hydrogen and 53.3% oxygen has an molar mass of 180.2 g/mol. What is the molecular formula?

  21. Example 4: • A compound containing 40.0% carbon, 6.7% hydrogen and 53.3% oxygen has an molar mass of 180.2 g/mol. What is the molecular formula? • Molecular Formula: C6H12O6

  22. In-Class Work • Download and complete the Empirical and Molecular worksheet from my Website • AND… • Hebden Questions: p. 91-95 Q’s 46 a,b,c,m,n 47-52 and 54

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