Thursday 5 January 2012

Percent Composition!

Today in chemistry class, Mr. Doktor taught us about percent composition by mass. We learned how to figure out the percent by mass of each element in a compound.



* To relate the mass of each element in a compound to the entire mass of the compound we use percent composition.



Example. H20--------- (2) molar mass of hydrogen in the compound / (18) total molar


mass of the compound = 0.111 = 11.11% of hydrogen


(16) molar mass of oxygen in the compound / (18) total molar mass of the compound


= 0.889 = 88.89% of oxygen


* To check your answer, add up all the percents and if the sum is 100 you did it right.


* 11.11%

+

* 88.89%


= 100%

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