Empirical and Molecular Formulas

Create a Placemat on Your Giant Whiteboard… Drill Create a Placemat on Your Giant Whiteboard…

What is the percent composition of Bromine in CuBr2? Drill What is the percent composition of Bromine in CuBr2?

Agenda Drill Review of HW Empirical/Molecular Formula Notes Case of the Chemical Culprit Extra Practice (HW if not finished in class) Looking Forward CHECK FOR UNDERSTANDING ON PERCENT COMPOSITION AND EMPIRICAL FORMULA NEXT CLASS!!!!

Case of the Chemical Culprit Ms. Fair’s room was left a mess the other day and found a mysterious substance on her desk. After watching the school’s cameras, she saw that there were 5 possible subjects and she examined their hands and found different substances on them. She determined the mystery substance, but did not have time to determine what the substances were on the suspects.

Your Task Use your notes to determine the empirical formula for the 5 different suspects After calculating all results, see Ms. Fair’s results in the front of the room to determine who the culprit was!

HW If you did not finish the additional practice, complete that for HW!!! 

Check for Understanding on Empirical Formula and Percent Composition Looking Forward Check for Understanding on Empirical Formula and Percent Composition Possible Lab – Have to try it first

Empirical Formula The lowest whole number ratio of atoms in a compound Formulas for ionic compounds are ALWAYS empirical (lowest whole number ratio) Examples: NaCl Al2(SO4)3 MgCl2

Molecular Formula The true number of atoms of each element in the formula of a compound Example: C2H8 P4O10

Molecular and Empirical Formulas Formulas for molecular compounds MIGHT be empirical (lowest whole number ratio) Molecular Empirical H2O C6H12O6 CH2O C12H22O11

Which of the following is NOT an empirical formula? Na2SO4 C6H5Cl N2H4 Sn3(PO4)4

Check for Understanding The lowest whole-number ratio of the elements in a compound is called? Empirical formula Molecular formula Binary formula Representative formula

Check for Understanding Which of the following compounds have the same empirical formula? CO2 and SO2 C7H14 and C10H20 C4H10 and C10H4 C6H12 and C5H14

Check for Understanding Which of the following is NOT true about empirical and molecular formulas? The molecular formula of a compound can be the same as its empirical formula. The molecular formula of a compound can be the same whole- number multiple of its empirical formula. Several compounds can have the same empirical formula, but have different molecular formulas. The empirical formula of a compound can be triple its molecular formula