Percentage Composition of Substances.ppt

Percentage Composition topic

2. Percentage composition
Indicates the relative amount of each element
present in a compound.

3. Calculating percentage
composition
Step 1 : Calculate molar mass
Step 2 : Divide the subtotal for each element’s
mass by the molar mass.
Step 3: Multiply by 100 to convert to a
percentage.

4. Example 1
1. Calculate the molar mass of water, H
2O.
 Step 1 – H- 2(1.01)= 2.02
 O – 1(16.0)= 16.0
 ________
 18.02

5. Step 2 2.02/18.02 X 100 = 11.21%
 16.0 /18.02 X 100 = 88.79 %
Water is composed of 11.21 % hydrogen and
88.79 % oxygen.

6. Example 2
Calculate the percentage composition of sucrose ,
C12H22O11.

7. Example 3
Find the percentage composition of hydrogen in
sulfuric acid.