Nitrogen has two isotopes. One has an atomic mass of 14.003 amu and a relative abundance of 99.63% while the other isotope has an atomic mass of 15.000 amu and a relative abundance of 0.37%. What is the average atomic mass for nitrogen?

Average atomic mass = 14.0067  amu.

Explanation:

Given data:

Abundance of 1st isotope  = 99.63%

Atomic mass of 1st isotope = 14.003 amu

Abundance of 2nd isotope  = 0.37%

Atomic mass of 2nd isotope = 15.000 amu

Solution:  

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass = (99.63×14.003)+(0.37×15.000) /100

Average atomic mass =  1395.119 + 5.55 / 100

Average atomic mass  = 1400.67 / 100

Average atomic mass = 14.0067  amu.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml