Entry Task: Feb 5 th - 6 th Block #1 Write the Question How many formula units are in 50.0 grams of Iron II oxide? You have 5 minutes!

Agenda: Discuss Particles Moles Grams Self Check on Concepts Discuss Self-Check Notes on Percent Composition HW: Percent Composition ws

I can… Calculate particles  moles  grams Explain what is meant by the percent composition of a compound.

Discuss Particles  Moles  Grams Avervision for answers

Clear off your Desk!! Calculators Periodic Tables Needed

Discuss Self Check Avervision for answers

Percent Composition is the percent of each element in a compound. Percent composition is a step in determining the ratio in elements in a compound/molecule.

Example: Magnesium oxide- MgO Its molar mass is g for Mg g for O, = g By just looking at this compound, It LOOKS like it 50/50 of magnesium oxide. But according to its molar mass, it is not 50/ g (Magnesium mass) grams (mass of MgO) Magnesium = 0.60 X 100 = 60% Oxygen g (oxygen mass) grams (mass of MgO) = 0.40 X 100 = 40%

Fe 2 O 3 Fe = x 2 = g O = x 3 = g g  g X 100 = 69.9% X 100 = 30.1% Iron III oxide  g

Barium hydroxide Ba(OH) 2 O= g X 2 = g Ba= g X 1 = g H= g X 2 = g g  g = X 100 = 80.1% = X 100 = 18.7% = X 100 = 1.2%

Lead (II) nitrate Pb(NO 3 ) 2 Pb= g X 1 = g N= g X 2 = g O= g X 6 = g  g = x100 = 62.6% g  g = x100 = 8.46%  g = x100 = 28.9%

Ammonium sulfate (NH 4 ) 2 SO 4 N= g X 2 = g H= g X 8 = 8.06 g S= g X 1 = g 1 mole = grams O= g X 4 = g  X 100 = 21.4 %  X 100 = 6.2%  X 100 = 23.6 %  X 100 = % add up % = 100%

Hydronium nitride (H 3 O) 3 N H= g X 9 = g N= g X 1 = g O= g X 3 = g 71.1 grams  71.1 grams x 100= = 12.7 %  71.1 grams x 100= = 67.6 %  71.1 grams x 100= = 19.7 %

Aluminum cyanide Al(CN) 3 Al= g X 1 = g N= g X 3 = g C= g X 3 = g 105 grams  105 grams x 100= = 25.6 %  105 grams x 100= = 34.3 %  105 grams x 100= = 40.0 %