Mr. Samaniego
Lawndale High
How many moles of ammonia are produced when
0.60 mol of nitrogen reacts with hydrogen?
mol = ? (NH3)
0.60 mol N2
0.60 mol

N2 + 3 H2
2 _ mol _ NH 
3
N2 

 1 _ mol _ N 2 
2 NH3
= 1.2 mol NH3

Balanced equations are necessary to find the
amount of product or reactant needed in a
chemical reaction.
Cu + O2
CuO
Calculate the number of grams of NH3 produced
by the reaction of 5.40 g of hydrogen with an
excess of nitrogen. The balanced equation is
mass = ? (NH3)
5.40 g H2
5.40 g

N2 + 3 H2
2 NH3
 1 _ mol _ H  2 _ mol _ NH  17 . 04 _ g _ NH
2
3
3
H2 
 

2 .02 _ g _ H 2   3 _ mol _ H 2  1 _ mol _ NH 3





= 30.4 g NH3
Lithium nitride reacts with water to form ammonia
and aqueous lithium hydroxide.
Li3N + 3H2O
NH3 + 3LiOH
a. What mass of water is needed to react with 32.9 g
of Li3N?
b. When the above reaction takes place, how many
molecules of NH3 are produced?
c. Calculate the number of grams of Li3N that must be
added to an excess of water to produce 15.0 L of NH3
(at STP).

Pages 358-361: 6-14 (skip 11a). (12/14/11, 12/15/11)
A + B
C
grams of A to grams of C:
grams A  mol A  mol C  grams C
mol of A to grams of C:
mol A  mol C  grams C
mol of A to mol of C:
mol A  mol C
grams of A to mol of C:
grams A  mol A  mol C
Calculate the number of grams of H2O produced
by the reaction of 12.5 g of nitrogen monoxide
with an excess of ammonia. The balanced
equation is
4NH3 + 6NO
5N2 + 6H2O
mass = ? (H2O)
12.5 g NH3
12.5 g

 1 _ mol _ NH   6 _ mol _ H O  18 .02 _ g _ H 2 O 
3
2
NH3
 
  1 _ mol _ H O 

2
17 .04 _ g _ NH 3  4 _ mol _ NH 3  


= 19.8 g H2O
After Ch 12 Quiz
How many molecules of oxygen are produced when
29.2 g of water is decomposed by electrolysis
according to this balanced equation?
2H2 + O2
molecules = ? (O ) 2H2O
29.2 g H2O
29.2 g
2
 1 _ mol _ H 2 O
H2O 
 18 . 0 _ g _ H 2 O




 1 _ mol _ O 2

 2 _ mol _ H O
2

  6 . 02 x10 _ molecules
 

1 _ mol _ O 2

23
= 4.88x1023 molecules O2
_ O2 



Nitrogen monoxide and oxygen gas combine to form
the brown gas nitrogen dioxide, which contributes to
photochemical smog. How many liters of nitrogen
dioxide are produced when 34 L of oxygen reacts with
an excess of nitrogen monoxide? (Assume @ STP.)
vol O2 = 34 L
vol = ? (NO2)
34 L
 1 _ mol _ O 2
O2 
 22 . 4 _ L _ O 2
Remember:
1 mol = 22.4 L
@STP
2NO + O2




 2 _ mol _ NO 2

 1 _ mol _ O
2

2NO2
  22 . 4 _ L _ NO 2
 
 1 _ mol _ NO
2

= 68 L NO2




Assuming STP, how many milliliters of oxygen are
needed to produce 20.4 mL SO3 according to this
balanced equation?
vol SO3 = 20.4 mL
vol = ? (mL O2)
20.4 mL SO3
2SO2 + O2
 1 _ mL _ O 2

 2 _ mL _ SO
3





2SO3
= 10.2 mL O2
Remember:
1 mol = 22.4 L
@STP