Why are there fractions in this chemical equation? NH2CH2COOH(s)+94O2→2CO2(s)+52H2O(l)+12N2(g) Thank you!?
Answers
Answer:
Because the equation was not properly balanced.
Explanation:
You're dealing with the combustion of glycine,
NH
2
CH
2
COOH
, which produces carbon dioxide,
CO
2
, water,
H
2
O
, and nitrogen gas,
N
2
.
Now, the idea with using fractional coefficients to balance chemical equations is that you must make sure that you don't end up with fractions of atoms.
For example, something like
1
2
N
2
(
g
)
makes sense because it describes half of one nitrogen molecule,
N
2
, which is equivalent to one atom of nitrogen.
1
2
×
2 atoms of N
=
1 atom of N
a
√
On the other hand, something like
5
2
H
2
O
(
l
)
does not make sense because it implies that you're dealing with
5
2
×
2 atoms of H
=
5 atoms of H
a
√
5
2
×
1 atom of O
=
2.5 atoms of O
a
×
You cannot have
2.5
atoms of oxygen because that would imply the splitting of atoms, which is not possible in ordinary chemical reactions.
The same goes for
9
4
O
2
, which is equivalent to
9
4
×
2 atoms of O
=
9
2
a
atoms of O
a
×
So, the best-case scenario here is that this version of the equation
NH
2
CH
2
COOH
(
s
)
+
9
4
O
2
(
g
)
→
2
CO
2
(
g
)
+
5
2
H
2
O
(
l
)
+
1
2
N
2
(
g
)
represents a step in the process of balancing the equation that describes the combustion of glycine. To get the correct balanced chemical equation, you'd have to get rid of the fractional coefficients.
To do that, multiply all the chemical species by
4
. You will have
4
NH
2
CH
2
COOH
(
s
)
+
9
O
2
(
g
)
→
8
CO
2
(
g
)
+
10
H
2
O
(
l
)
+
2
N
2
(
g
)
If you want to have a correct balanced chemical equation and still use fractional coefficients, you can divide all the chemical species by
2
. This will get you
2
NH
2
CH
2
COOH
(
s
)
+
9
2
O
2
(
g
)
→
4
CO
2
(
g
)
+
5
H
2
O
(
l
)
+
N
2
(
g
)
This time, the fractional coefficient makes sense because it gets you
9
2
×
2 atoms of O
=
9 atoms of O
a
√
So remember, you can use fractional coefficients to balance chemical equation, but make sure that the they make sense at the level of the atom.
Any fractional coefficient that gives you fractions of an atom is not used correctly.