1. balanced chemical reaction
Chemical Reactions
reactants
product 2 H2
+ O2  2
H2O
(g)
(g)
(l)
to yield
reacts with
2 H atoms 4
2 H atoms 4
2 O atoms
1 O atom 2
(s) = solid
conservation of mass
(aq) = aqueous
 = heat
balanced chemical reaction
h = light

2. described by balanced reactionH2
+ O2 
H2O 2
(g)
(l)
coefficients
atomic
4 H atoms
2 O atoms
4 H atoms
2 O atoms
molecular
2 H2
1 O2
2 H2O
molar
2 mol H2
1 mol O2
2 mol H2O
2 x
2.016
g H2
32.00
g O2
2 x
g H2O
18.02
mass
36.04 g reactants
36.04 g products
stoichiometry
described by balanced reaction

3. Solid iron reacts with oxygen to form solid iron(III) oxide
1. Determine reactants and products
Fe (s)
O2 (g)
Fe O (s) 2 3
2. Write the unbalanced equation
Fe (s) +
O2 (g)
Fe O 2
3 (s)
3. Balance the atoms of one element 4 2
Fe (s)
O2 (g)
Fe O 2
3 (s) + 3 2 4
(55.84 g) + 3
(32.00 g) 2
( g)

4. Magnesium reacts with hydrochloric acid
to make hydrogen gas and magnesium chloride 1. Mg
(s)
HCl
(aq) H2
(g) Mg Cl
(aq) 2 3. 2.
Mg (s) + HCl(aq)  H2(g) + MgCl2 (aq) 2
Limiting reagent
1.1g Mg
HCl H2
0.05 mol
0.045 mol
0.022 mol
0.090 mol
0.045 mol
0.180 mol
0.050 mol
0.240 mol
0.050 mol
0.360 mol
0.050 mol

5. 2 H2
+ O2  2
H2O
(g)
(g)
(l)

6. Ammonia reacts with oxygen to produce
nitrogen monoxide, a gas, and water 1.
NH3 (g)
O2 (g)
NO (g)
H2O (l) 2.
NH3 (g) +
O2 (g)
NO (g) +
H2O (l) 3. 2
NH3 (g)
O2 (g)
NO (g)
H2O (l) + 2 3
5/2 4 5 4 6
If we start with 10.0 g of ammonia,
how much water (l) can we produce?

7. If we start with 10.0 g of ammonia, how much water (l) can we produce?
NH3 (g)
O2 (g)
NO (g)
H2O (l) + 4 6 5
10.0 g NH3
1 mol NH3 =
0.587 mol NH3
17.03 g
0.587 mol NH3
6 mol H2O
18.02
g H2O
= g H2O
15.9
4 mol NH3
1 mol H2O
If we start with 10.0 g of ammonia and 10.0 g O2
how much water (l) can we produce?

8. If we start with 10.0 g of ammonia and 10.0 g O2
how much water (l) can we produce?
NH3 (g)
O2 (g)
NO (g)
H2O (l) + 4 6 5
10.0 g NH3
1 mol NH3
17.0 g =
0.587 mol NH3
10.0 g O2
1 mol O2 =
0.313 mol O2
limiting
reagent
32.0 g
0.587 mol NH3
5 mol O2
= mol O2
4 mol NH3
0.313 mol O2
6 mol H2O
18.0 g
= 6.76 g H2O
5 mol O2
1 mol H2O
theoretical yield

9. If we start with 10.0 g of ammonia and 10.0 g O2
how much water (g) can we produce?
NH3 (g)
O2 (g)
NO (g)
H2O (l) + 4 6 5
10.0 g NH3
1 mol NH3
17.03 g =
0.587 mol NH3
limiting
reagent
10.0 g O2
1 mol O2 =
0.313 mol O2
32.00 g
Which reagent will be left after the reaction is
complete? How much of it will remain (g)?
NH3
0.313 mol O2
4 mol NH3
= .250 mol NH3 consumed
5 mol O2
.587 mol
mol =
.337 mol NH3
x g/mol
= 5.74 g NH3

10. Hydrofluoric acid is made by treating
calcium fluoride with sulfuric acid.
The other product is calcium sulfate.
Ca F 2 H+
SO42- H+ F-
Ca2+
SO42-
2 + - 2
CaF2 (s)
+ H2SO4 (l)
 HF (l) 2
+ CaSO4 (s)
6.00 kg CaF2
excess H2SO4
2.86 kg HF
limiting reagent
6.00 kg CaF2
1000 g
1 mol CaF2
2 mol HF
g HF
1 kg
1 kg
78.08 g CaF2
1 mol CaF2
1 mol HF
1000 g
3.07 kg HF
% yield =
actual
= 2.86 kg
= 93.2 %
theoretical
3.07 kg