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Percentage Composition. Percentage composition. Indicates the relative amount of each element present in a compound. Calculating percentage composition. Step 1 : Calculate molar mass Step 2 : Divide the subtotal for each element’s mass by the molar mass.
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Percentage composition • Indicates the relative amount of each element present in a compound.
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.
Example 1 • 1. Calculate the molar mass of water, H2O. • Step 1 – H- 2(1.01)= 2.02 • O – 1(16.0)= 16.0 • ________ • 18.02
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.
Example 2 • Calculate the percentage composition of sucrose , C12H22O11.
Example 3 • Find the percentage composition of hydrogen in sulfuric acid.