2. HW Quiz A student placed a piece of tin in hydrochloric acid. Hydrogen gas was given off, then the liquid was evaporated off. The remaining solid, Sn x Cl y was massed. Use the data below to determine the empirical formula of tin chloride (Sn x Cl y ). Mass of beaker 52.356g Mass of tin and beaker before reaction 111.726g Mass of tin chloride and beaker after reaction 138.331g Determine the formula of Sn x Cl y

3. Agenda WB Worksheet 2.5 Empirical Practice Molecular Notes Homework: Empirical Formula Lab Quiz tomorrow! U5 w/s 3

4. Molecular Formulas Definition Example: Show the types and numbers of atoms in a compound. (H 2 O 2 ) Same as the empirical formula or a whole # multiple of it. C 6 H 12 O 6 = molecular formula of glucose. CH 2 O= empirical formula of glucose (or any sugar) H 2 O = empirical and molecular formula of water

5. Molecular Formulas Needed: Need (or need to be able to calculate): Empirical Formula (you may need to find this ) Formula Mass or Molar Mass of Molecular Compound (must be given)

6. Molecular Formulas Solve The empirical formula of a compound is P 2 O 5 and it has a formula mass of 283.889g. What is the molecular formula of the compound?

7. Molecular Formulas- Steps 1. Molar mass of the molecular compound. 283.889g (from problem) 2. Empirical formula of the compound. P 2 O 5 (from problem) 3. Molar mass of the empirical formula. 2(Mass of P) + 5(Mass of O) = 141.943g 4. Molar mass of molecular formula (must be the one given)/ molar mass of empirical formula (always the same or smaller #) 283.889g / 141.943g =2.0000 5. Multiply subscripts in empirical formula by answer above 2(P 2 O 5 ) = P 4 O 10

8. Remember! By definition, the molecular formula is the same as or a whole number multiple of the empirical formula… If your number did not come out perfect- CHECK YOUR MATH!

9. Solve the following: 4. A compound has 7.6g Nitrogen, 17.4g Oxygen, and a molar mass of 138g. What is the empirical formula? What is the molecular formula? Write the name of the compound!