Lesson: Percent Composition
Percent Composition
Percent Composition
gives the percentage of a substance
Percent Composition
gives the percentage of a substance
that is made up of a certain element.
For example,
For example,
the compound SO2
For example,
the compound SO2
(sulfur dioxide)
For example,
the compound SO2
(sulfur dioxide)
has a molar mass of 64.058
For example,
the compound SO2
Because it has ONE sulfur
(sulfur dioxide)
has a molar mass of 64.058
For example,
the compound SO2
Because it has ONE sulfur
(sulfur dioxide)
has a molar mass of 64.058
one sulfur
For example,
the compound SO2
Because it has ONE sulfur
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
one sulfur
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
two oxygen
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
each with a mass of 16 for a total of 32
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
two oxygen
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
each with a mass of 16 for a total of 32
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
this
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
each with a mass of 16 for a total of 32
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
this
plus
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
each with a mass of 16 for a total of 32
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
this
plus
this
For example,
the compound SO2
and it has TWO oxygen
Because it has ONE sulfur
each with a mass of 16 for a total of 32
with a molar mass of 32.06
(sulfur dioxide)
has a molar mass of 64.058
this
plus
equals this
this
Find the molar mass of the following elements:
Carbon
Hydrogen
Nitrogen
Oxygen
12.01
?
1.01
?
14.01
?
16.00
?
Let's find the molar mass H2O.
Let's find the molar mass H2O.
First, find the molar mass of H and O
Let's find the molar mass H2O.
First, find the molar mass of H and O
O
H
16
?
1.01
?
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
First, find the molar mass of H and O
O
H
16
1.01
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
First, find the molar mass of H and O
O
H
16
1.01
x
x
1
?
2
?
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
First, find the molar mass of H and O
O
H
16
1.01
x
x
1
2
=
=
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
finally, add the products
First, find the molar mass of H and O
O
H
16
1.01
x
x
1
2
=
=
16
2.02
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
finally, add the products
First, find the molar mass of H and O
2.02 + 16 =
O
H
16
1.01
x
x
1
2
=
=
16
2.02
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
finally, add the products
First, find the molar mass of H and O
2.02 + 16 =
O
H
16
1.01
x
x
18.02
1
2
=
=
16
2.02
Let's find the molar mass H2O.
then multiply each molar mass by their subscript
finally, add the products
First, find the molar mass of H and O
2.02 + 16 =
O
H
16
1.01
x
x
18.02
1
2
=
=
16
2.02
molar mass of H2O
Find the molar mass of the following compounds:
H2O2
NF3
PCl4
Al2O3
71.01
?
172.77
?
34.04
?
101.96
?
To find percent composition
To find percent composition
you find the molar mass first
To find percent composition
you find the molar mass first
SO2
To find percent composition
S
O
you find the molar mass first
SO2
To find percent composition
S
O
you find the molar mass first
SO2
32.06
?
16
?
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
?
2
?
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
32.06
32
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
32.06
32
+
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
To find percent composition
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
molar mass
Then divide each element's molar mass by the
To find percent composition
total molar mass
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
Then divide each element's molar mass by the
To find percent composition
total molar mass
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
Then divide each element's molar mass by the
To find percent composition
total molar mass
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
= .4995
?
= .5005
?
Then divide each element's molar mass by the
To find percent composition
total molar mass
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
= .4995
= .5005
Then divide each element's molar mass by the
To find percent composition
total molar mass, then multiply them both by 100
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
= .4995
= .5005
Then divide each element's molar mass by the
To find percent composition
total molar mass, then multiply them both by 100
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
= .4995x100=
= .5005x100=
49.95%
?
50.05%
?
Then divide each element's molar mass by the
To find percent composition
total molar mass, then multiply them both by 100
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
So SO2 is
= .4995x100=
= .5005x100=
49.95%
50.05%
Then divide each element's molar mass by the
To find percent composition
total molar mass, then multiply them both by 100
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
So SO2 is
50.05% Sulfur
= .4995x100=
= .5005x100=
49.95%
50.05%
Then divide each element's molar mass by the
To find percent composition
total molar mass, then multiply them both by 100
S
O
you find the molar mass first
SO2
32.06
16
x
x
1
2
=
=
64.06
32.06
32
+
÷ 64.06
÷ 64.06
So SO2 is
50.05% Sulfur
and 49.95% Oxygen
= .4995x100=
= .5005x100=
49.95%
50.05%
Find the percent composition of H2O
Find the percent composition of H2O
O
H
Find the percent composition of H2O
O
H
16
?
1.01
?
Find the percent composition of H2O
O
H
16
1.01
x
x
1
?
2
?
Find the percent composition of H2O
O
H
16
1.01
x
x
1 =
2 =
16
?
2.02
?
Find the percent composition of H2O
O
H
16
1.01
x
x
1 =
2 =
18.02
16
2.02
+
Find the percent composition of H2O
O
H
16
1.01
x
x
1 =
2 =
18.02
16
2.02
+
÷ 18.02 =
÷ 18.02 =
.8879
?
.1121
?
Find the percent composition of H2O
O
H
16
1.01
x
x
1 =
2 =
18.02
16
2.02
+
÷ 18.02 =
÷ 18.02 =
.8879 x100=
.1121 x100=
88.79
?
11.21
?
Find the percent composition of H2O
O
H
16
1.01
11.21
88.79
x
x
1 =
2 =
18.02
16
2.02
% Oxygen
?
% Hydrogen
?
+
÷ 18.02 =
÷ 18.02 =
.8879 x100=
.1121 x100=
88.79
11.21
Find the percent composition of NO3.
Find the percent composition of NO3.
O
N
Find the percent composition of NO3.
O
N
16
?
14.01
?
Find the percent composition of NO3.
O
N
16
14.01
x
x
1
?
3
?
Find the percent composition of NO3.
O
N
16
14.01
x
x
1
3
=
=
48
?
14.01
?
Find the percent composition of NO3.
O
N
16
14.01
x
x
1
3
=
=
48
14.01
+
Find the percent composition of NO3.
O
N
16
14.01
x
x
1
3
=
=
48 ÷ 62.01 =
62.01
14.01 ÷ 62.01 =
+
.7741
?
.2259
?
Find the percent composition of NO3.
O
N
16
14.01
x
x
1
3
=
=
48 ÷ 62.01 =
62.01
14.01 ÷ 62.01 =
+
.7741x100=
.2259 x100=
77.41
?
22.59
?
Find the percent composition of NO3.
O
N
16
14.01
x
x
77.41%
22.59%
1
3
=
=
48 ÷ 62.01 =
62.01
14.01 ÷ 62.01 =
+
Oxygen
?
Nitrogen
?
.7741x100=
.2259 x100=
77.41
22.59
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