Thursday, January 24, 2013 Percent Composition. Students will be able to: Calculate the percent...
-
Upload
caren-goodwin -
Category
Documents
-
view
217 -
download
0
description
Transcript of Thursday, January 24, 2013 Percent Composition. Students will be able to: Calculate the percent...
Thursday, January 24, 2013Percent 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
100compound of mass total
element of masscomp %
First Determine molar mass of Cu2SCu: 2x 63.5 = 127S: 1 x 32 = 32 mass = 159g/mol
Find the % composition of Cu2S.
%Cu =2*63.5 g Cu159 g Cu2S
100 =79.8% Cu
100 =%S =32 g S
159 g Cu2S 20.2% S
How many grams of copper are in a 38.0-gram sample of Cu2S?
(38.0 g Cu2S)(0.798) = 30.3 g Cu
Cu2S is 79.8% Cu
100 =%H2O = 36.0 g147.0 g
24.5%H2O
Find the mass percentage of water in calcium chloride dihydrate, CaCl2•2H2O?
Determine the percent composition of Mn(SO4)2.
How many grams of manganese are in a 500g sample of Mn(SO4)2?
What percent of PO5 is phosphorous?