nitrogen has following two isotopes with relative abundance and atomic mass as following
Answers
Answer:
The percent abundance of N-15 is 0.6403%.
Explanation:
The atomic mass of an element is a weighted average of its isotopes in which the sum of the abundance of each isotope is equal to 1 or 100%.
Formula for Calculating Isotope Percent Abundance
(
x
)
(
mass
)
+
(
1
−
x
)
(
mass
)
=
100
%
In order to determine the percent abundance of nitrogen-15:
Let
x
=
% of nitrogen-15
(
1
−
x
)
=
% of nitrogen-14
100
%
=
14.0067
, the atomic mass of nitrogen
Set up the formula for nitrogen-15 and nitrogen-14.
15.001
x
+
14.00031
(
1
−
x
)
=
14.0067
Simplify the left-hand side.
15.001
x
+
14.00031
−
14.00031
x
=
14.0067
Simplify.
0.9979
x
+
14.00031
=
14.0067
Subtract
14.00031
from both sides.
0.9979
x
=
14.0067
−
14.00031
Simplify.
0.9979
x
=
0.00639
Divide both sides by
0.9979
.
x
=
0.006403
×
100
=
0.6403
%
nitrogen-15
In case you're interested, the percent abundance of nitrogen-14 is
1
−
x
=
1
−
0.006403
=
0.993597
0.993597
×
100
=
99.3597
%
nitrogen-14
99.3597
%
+
0.6403
%
=
100
%