Percent Composition % Oxides % hydrides

Chemical Formulas Can Give Percentage Composition CO and CO2 are both C and O, but have diff. % compositions.

Percent Composition by mass percentage composition- % by mass of each element in a compound. verifies substance’s identity used to compare ratio of mass contributed by element in 2 different subsstances mass element molar mass compound x 100%

Percentage Composition of Iron Oxides

Calculate % comp. of copper(I) sulfide a copper ore called chalcocite. Step 1 find Molar mass Step 2 divide coppers contribution by molar mass , then X by %100 Step 3 divide sulfurs contribution by molar mass, then X by %100

Molar Mass and Percent Composition Find molar mass of Cu2S. 2(Cu)(63.55g/mol) = 127.10 + 1(S)(32.07g/mol) = 32.07 + 159.17g/mol Cu2S Divide mass of ea. element by molar mass of compound 79.85%Cu 20.15% S

% Hydrate hydrate: 1,2,3,4,5,6,7,8,9,10 compound containing water Prefixes represent # of water molecules attached to parent mono,di,tri,tetra,penta,hexa,hepta,octa,nona,deca 1,2,3,4,5,6,7,8,9,10 Calculate % comp Ce(SO4)2• 4H2O Molar mass: ______________ % Ce :____________________ % S : ____________________ % 0 : ____________________ % H2O :___________________

% Hydrate hydrate: 1,2,3,4,5,6,7,8,9,10 compound containing water Prefixes represent # of water molecules attached to parent mono,di,tri,tetra,penta,hexa,hepta,octa,nona,deca 1,2,3,4,5,6,7,8,9,10 Calculate % comp Ce(SO4)2• 4H2O Molar mass: _ 404.23g/mol Ce(SO4)2•4H2O % Ce :____________________34.65%Ce % S : ____________________15.86%S % 0 : ____________________ 31.67%O % H2O :___________________ 17.83%H2O

% Hydrate hydrate: 1,2,3,4,5,6,7,8,9,10 compound containing water Prefixes represent # of water molecules attached to parent mono,di,tri,tetra,penta,hexa,hepta,octa,nona,deca 1,2,3,4,5,6,7,8,9,10 Calculate % comp Ce(SO4)2• 4H2O Molar mass: 404.23g/mol Ce(SO4)2•4H2O _______________________________________=34.65%Ce _______________________________________=15.86%S _______________________________________=31.67%O ______________________________________=17.83%H2O