1. Empirical Formula and Percent Composition Practice

2. Empirical Formula/Percent Composition
Empirical Formula – the lowest whole-number ratio of the elements in a compound.
Examples:
H2O, CH4, H2SO4
NOT empirical formulas:
H2O2, C6H12O6

3. Simplify the following into their Empirical Formulas:
Na2CO3
N2O4
C6H18O3
S2O2
B4H12
P4H10

4. Steps to Find Empirical Formula:
Change percent to grams (assume gram sample)
Convert grams to moles
Divide each element by the smallest # of moles
If needed, multiply ALL by some integer to get whole numbers
If we were given grams we would start on step 2
If we were given moles we would start on step 3

5. Practice Problem %  Empirical Formula
NutraSweet is 57.14% C, 6.16% H, 9.52% N, and % O.  Calculate the empirical formula of NutraSweet.
Because 2.5 is too far to round, multiply by 2
C14H18N2O5

6. Percent Composition
Remember that finding the percent composition can be done by:
g of element x 100 =
g of whole compound