Notes- Empirical & Molecular Formulas

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Unit 7: Notes - Introducing Empirical and Molecular Formulas
Molecular Formula is a formula indicating the actual number of atoms of each element making up a
molecule. CAN BE REDUCED!!!
Empirical formula is the formula giving the simplest ratio between the atoms of the elements present in
a compound. CAN NOT BE REDUCED
A. Identify the following compounds as Empirical or Molecular
1)
P4O6
_________________
5)
C6H8O6
___________________
____________________________
6)
CuC2O4
___________________
3) CH2OHCH2OH __________________
7)
Hg2F2
___________________
4) BrCl2
8)
C12H22O11 ___________________
2) C6H9
__________________
Converting Molecular Formula to Empirical Formula
Example 1: Hydrogen Peroxide; Molecular Formula is H2O2  subscripts are divisible by 2
Empirical Formula is HO
Example 2: Glucose; Molecular Formula is C6H12O6  subscripts are divisible by 6
Empirical Formula is CH2O
B. Reduce the Molecular Formulas below to their simplest Empirical Formula
9) P4O6
__________
10) C6H9
__________
11) C6H8O6 __________
12) Hg2F2
__________
13) C4H8O2
__________
14) C4H4O4
__________
Find the Empirical Formulas for the following:
15) A compound composed of 9.93% Carbon, 58.6% Chlorine and 31.4% Fluorine.
Change %
to g
Gram to mole
(divide by Molar
mass)
DO NOT ROUND!!
Divide by smallest
Multiply ‘till
whole
Or Round
C
Cl
F
Answer: the empirical formula is ______________________
16) A compound is 30% Nitrogen and 70% Oxygen. Find the empirical formula of the compound.
N
O
Answer: the empirical formula is ______________________
17)
Find the Molecular Formulas for the following compounds:
1. Find the molar mass of the empirical formula.
2. Divide the Given by the molar mass you found to get the value of n
3. Multiply the subscripts of the empirical formula by the value of n to get the molecular
formula
a) A compound with a molecular mass of 70 g and an empirical formula of CH2.
b) A compound with a molecular mass of 46.0 g and an empirical formula of NO2.
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