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WHERE DO YOU
LOOK IF YOU’VE
LOST YOUR MIND?
-Bernard Malamud-
REVIEW
WHAT INFORMATION DOES THE FOLLOWING
FORMULA TELL YOU?
2 (NH4)3PO4
WHAT INFORMATION DOES THE FOLLOWING
FORMULA TELL YOU?
2 (NH4)3PO4
1)You have 2 formula units of ammonium
phosphate, or
2)You have 2 moles of ammonium phosphate
3)In those 2 formula units, you have 6 atoms of
nitrogen, 24 atoms of hydrogen, 2 atoms of
phosphorus, 8 atoms of oxygen, or
4)In those 2 moles, you have 6 moles of nitrogen,
24 moles of hydrogen, 2 moles of phosphorus,
and 8 moles of oxygen
CALCULATE THE MOLAR MASS OF ZnSO4.
CALCULATE THE MOLAR MASS OF ZnSO4.
1 Zn = 1 x 65 = 65
1 S = 1 x 32 = 32
4 O = 4 x 16 = 64
Molar Mass = 161 g/mole
HOW MANY MOLES OF K2SO4 ARE IN 20
GRAMS?
HOW MANY MOLES OF K2SO4 ARE IN 20
GRAMS?
First, calculate the molar mass:
K = 2 x 39 = 78
S = 1 x 32 = 32
O = 4 x 16 = 64
•Molar mass = 174 g/mole
# moles = 20 g / 174 g/mole = 0.115 mole
HOW MANY MOLECULES OF C2H5OH ARE IN 2.5
MOLES?
HOW MANY MOLECULES OF C2H5OH ARE IN 2.5
MOLES?
1 mole = 6.023 x 1023 molecules
# molecules = 2.5 moles x 6.023 x 1023 molecules/mole
= 1.51 x 1024 molecules
HOW MANY GRAMS OF PbI2 ARE IN 8.4 X 1022
MOLECULES?
HOW MANY GRAMS OF PbI2 ARE IN 8.4 X 1022
MOLECULES?
# moles = 8.4 x 1022 / 6.023 x 1023
= 1.39 x 10-1 = 0.139 moles
Molar mass of PbI2 = 207 + 2(127) = 461 g/mole
# grams = 461 g/mole x 0.139 moles
= 64 g
BALANCE THE FOLLOWING EQUATIONS, AND TELL
WHAT KIND OF REACTION THE EQUATION
REPRESENTS:
a.C4H10 + O2 → CO2 + H2O
b.Fe + Cl2  FeCl3
c.Cu + AgNO3  Cu(NO3)2 + Ag
d.Pb(NO3)2 + AlCl3  Al(NO3)3 + PbCl2
e.KClO3  KCl + O2
BALANCE THE FOLLOWING EQUATIONS, AND TELL
WHAT KIND OF REACTION THE EQUATION
REPRESENTS:
a.2 C4H10 + 13 O2 → 8 CO2 + 10 H2O
b.2 Fe + 3 Cl2  2 FeCl3
c.Cu + 2 AgNO3  Cu(NO3)2 + 2 Ag
d.3 Pb(NO3)2 + 2 AlCl3  2 Al(NO3)3 + 3 PbCl2
e.2 KClO3  2 KCl + 3 O2
WHAT ARE THE SUBSTANCES ON THE LEFT
SIDE OF A CHEMICAL REACTION CALLED?
WHAT ARE THE SUBSTANCES ON THE RIGHT
SIDE OF CHEMICAL REACTION CALLED?
WHAT ARE THE SUBSTANCES ON THE LEFT
SIDE OF A CHEMICAL REACTION CALLED?
REACTANTS
WHAT ARE THE SUBSTANCES ON THE RIGHT
SIDE OF CHEMICAL REACTION CALLED?
PRODUCTS
WHAT IS THE LAW OF CONSERVATION OF
MASS?
WHAT IS THE LAW OF CONSERVATION OF
MASS?
IN A CHEMICAL REACTION, MATTER IS
NEITHER CREATED OR DESTROYED, ONLY
REARRANGED.
HOW DOES THE LAW OF CONSERVATION
OF MASS APPLY TO A CHEMICAL
EQUATION?
HOW DOES THE LAW OF CONSERVATION
OF MASS APPLY TO A CHEMICAL
EQUATION?
YOU HAVE THE SAME NUMBER OF EACH
TYPE OF ATOMS ON BOTH SIDES OF THE
EQUATION – THE EQUATION IS BALANCED.
2 NH3 + H2SO4  (NH4)2SO4
How many grams of ammonia (NH3) would be
required to make 1 kilogram of ammonium sulfate?
How many grams of ammonia (NH3) would be required
to make 1 kilogram of ammonium sulfate?
X
1000 g
2 NH3 + H2SO4  (NH4)2SO4
34
128
X / 34 = 1000 / 128
X = (1000 x 34) / 128 = 265.6 g
Note: molar mass of ammonium sulfate = 128 g/mole
molar mass of ammonia = 17 g/mole
How many moles of iron, Fe, would be required to
make 40 grams of hydrogen, H2?
2 Fe + 6 HCl  2 FeCl3 + 3 H2
How many moles of iron, Fe, would be required to
make 40 grams of hydrogen, H2?
2 Fe + 6 HCl  2 FeCl3 + 3 H2
Molar mass of H2 = 2 g/mole
# moles H2 = 40 g/2 g/mole = 20 moles
X
20
2 Fe + 6 HCl  2 FeCl3 + 3 H2
2
3
X/2 = 20/3
so
X = 20/3 x 2 = 13.3 moles
A COMPOUND CONTAINS THE ELEMENTS
COPPER AND CHLORINE IN A RATIO OF 1
COPPER : 2 CHLORINE.
WHAT IS THE EMPIRICAL FORMULA FOR THIS
COMPOUND?
WHAT IS THE % COMPOSITIONOF COPPER?
WHAT IS THE % COMPOSITION OF
CHLORINE?
EMPIRICAL FORMULA: CuCl2
Molar mass = 63.5 + 2(35.5) = 134.5 g/mole
% Cu = (63.5 / 134.5) x 100 = 47.2 %
% Cl = (71 / 134.5) x 100 = 52.8 %