Chemistry Reference
In-Depth Information
(b)
2 H
2
(g)
O
2
(g) £ 2 H
2
O(
/
)
Balanced
chemical
equation
Millimoles
of H
2
O
Definition
of milli-
Moles
of H
2
O
Moles
of O
2
Avogadro's
number
Molecules
of O
2
10
23
molecules O
2
1 mol O
2
1 mol H
2
O
1000 mmol H
2
O
a
1 mol O
2
2 mol H
2
O
a
6.02
425 mmol H
2
O
a
b
b
b
10
23
molecules O
2
1.28
The main difference between parts (a) and (b) is that the values of more
factors have to be stated in the problem in part (a) than in part (b).
Practice Problem 10.12
How many
SO
2
molecules does it take to
combine with
O
2
to produce 0.751 mol of SO
3
?
EXAMPLE 10.13
Calculate the number of molecules of
CO
2
that can be produced by complete
combustion of 12.5 g of gaseous
C
4
H
10
.
Solution
The balanced equation for the reaction is
2 C
4
H
10
(g)
13 O
2
(g) £ 8 CO
2
(g)
10 H
2
O(g)
Balanced
chemical
equation
Grams
of C
4
H
10
Molar
mass
Moles
of C
4
H
10
Moles
of CO
2
Avogadro's
number
Molecules
of CO
2
10
23
molecules CO
2
1 mol CO
2
a
1 mol C
4
H
10
58.1 g C
4
H
10
8 mol CO
2
2 mol C
4
H
10
a
6.02
12.5 g C
4
H
10
b
a
b
b
10
23
molecules CO
2
5.18
Practice Problem 10.13
Calculate the mass of
H
2
O
produced by the
10
22
complete combustion of
4.57
molecules of C
4
H
10
.
EXAMPLE 10.14
Calculate the mass of
H
2
O
that can be prepared by the reaction of 4.51
10
22
O
2
molecules with hydrogen gas.
