Thursday, January 24, 2013 Percent Composition. Students will be able to: Calculate the percent composition of chemical compounds.

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Presentation transcript:

Thursday, January 24, 2013 Percent Composition

Students will be able to: Calculate the percent composition of chemical compounds.

The percent composition tells us the % by mass of each type of element in a compound. To find % comp by mass, you take the mass of the element in the compound and divide by the total mass of the compound

the percentage by mass of each element in a compound

First Determine molar mass of Cu 2 S Cu: 2x 63.5 = 127 S: 1 x 32 = 32mass = 159g/mol Find the % composition of Cu 2 S. %Cu = 2*63.5 g Cu 159 g Cu 2 S  100 = 79.8% Cu  100 = %S = 32 g S 159 g Cu 2 S 20.2% S

How many grams of copper are in a 38.0-gram sample of Cu 2 S? (38.0 g Cu 2 S)(0.798) = 30.3 g Cu Cu 2 S is 79.8% Cu

 100 = %H 2 O = 36.0 g g 24.5% H 2 O Find the mass percentage of water in calcium chloride dihydrate, CaCl 2 2H 2 O?

Determine the percent composition of Mn(SO 4 ) 2. How many grams of manganese are in a 500g sample of Mn(SO 4 ) 2 ? What percent of PO 5 is phosphorous?