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Percent composition is used to find the percentage of elements in a compound. One must know the molar mass of the elements and the compound in order to get percent composition. For instance, the percent composition of oxygen in water is 89%. The molar mass of water is 18g/mol, and oxygen has a molar mass of 16g/mol. 16 divided by 18 is .89. Multiply this by 100 and you get 89%. This leaves hydrogen making up 11% of the water compound. This quiz will cover basic percent composition problems. You will need a calculator and a periodic table. Select the best answer from the choices.
What is the percentage of oxygen in carbon dioxide?
30%
70%
72.7%
32.7%
What is the percentage of chlorine in sodium chloride?
60.7%
70.9%
65.9%
64.5%
What is the molar mass of sucrose?
784g
456g
129g
342g
What is the percentage of carbon in sucrose?
34.9%
42.1%
24.5%
87%
What is the percentage of oxygen in sucrose?
51.5%
45.6%
23%
78.02%
The _______ is the percent by mass of each element in a compound. It is calculated in a similar way that we just indicated for the peanut butter.
Molecular composition
Molar percent composition
Percent composition
Mole composition
Dichlorineheptoxide (Cl2O7) is a highly reactive compound used in some organic synthesis reactions. Calculate the percent composition of dichlorineheptoxide.
12.50g
13g
14.75g
11g
Processes are described for calculating the percent composition of a material based on mass or on chemical composition.
True
False
