Arzie R. Thomas G. W. Carver Area High School
13100 South Doty Road
Chicago, IL 60627
Upon the completion of this lesson when asked 95% of the students will
orally, on written test or demonstrate how to find an empirical formula.
Find the molecular formula, given the molecular mass and the empirical
Squares of paper with symbols and charges; squares of paper with carbon and
it's electron dots and hydrogen and it's electron dots.
1. Define empirical formula.
2. Pass out ions and have students form formulas.
3. Have students give you formulas; you place the formulas on the
4. Go through the formulas and point out the correct formulas, indicate
why they are correct, and go through the wrong ones and correct them.
Tell students that these are ionic formulas and they are always written
in their empirical formula.
5. Pass out ions of carbon with its electron dots and hydrogen with its
electron dots. Explain that the organic compounds are not like the
inorganic compounds, some of them have two formulas.
6. Have the students make formulas of some of the alkanes.
7. Get the formulas and place them on the board.
8. Go through each formula for correctness and get the empirical formulas.
9. After the students are sure that they fully understand empirical
formulas, assign them problems to find the empirical formulas.
10. Give the student the molecular mass for their empirical formula and
show them how to find the molecular formula.
ll. After the student are sure that they understand assign them problems.
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