DO NOW! On Notebook Paper… How many liters are in 0.32 moles of Argon gas? How many atoms are in 292 grams of CO₂?

Unit: Chemical Quantities Notes Unit: Chemical Quantities Calculating Percent Composition

After today, you will be able to… Calculate percent composition for various compounds

Percent Composition ____________ Indicates the makeup of a substance based on mass. (Example: 50% carbon by mass) ____________ Mass of element x 100 % element = Mass of compound

Example: What is the % Lithium in Li2O? 13.88 +16.00 29.88 13.88 %Li = _______ x 100 = 46.45% Li 29.88

Example: What is the % of each element in Ba3(AsO4)2? 411.99 149.84 +128.00 689.83 %Ba = ______ 411.99 x 100 = 59.723% Ba 689.83 %As = ______ 149.84 x 100 = 21.721% As 689.83 %O = ______ 128.00 x 100 = 18.555% O 689.83

Example: What is the % of each element in Ba3(AsO4)2? (#2 on WS)

Time to Practice! Complete WS HOMEWORK: Time to Practice! Complete WS

25 points 50 points 100 points % H in CH4 % O in K3(PO4) %C in Mg(C2H3O2)2 % Na in NaCl % H in H(NO2) % N in Be(CN)2