Question

The atomic musses of 14N7 (99. 64 percent) and 15N7 (0.36 percent) are 14.00307 amu and 15.0001 amu,
respectively. Calculate the average atomic mass of nitrogen. The percentages in parentheses denote the relative abundances C01​

Answer 1

Given:

for $N^{14 } _{7}$

relative abundance = 99.64%

atomic mass = 14.00307amu

for $N^{15 } _{7}$

relative abundance = 0.36%

atomic mass = 15.0001 amu

To Find:

the average atomic mass of nitrogen =?

Solution:

we know that,

the average atomic mass of nitrogen = total atomic mass / total abundance

now, total abundance = 100%

total atomic mass = relative abundance × atomic mass

                             = (99.64 × 14.00307) + (0.36 × 15.0001)

                            = 1400.66593

now, put the value in above equation

the average atomic mass of nitrogen = 1400.66593/100

                                                             = 14.006

Hence, the average atomic mass of nitrogen is 14.006 u