(i) How would you define the terms atomic mass and molecular mass ? (ii) Nitrogen occurs in nature in the form of two isotopes with atomic masses 14 and 15 respectively. If the average atomic mass of nitrogen is 14.0067, what is the percent abundance of the two isotopes ?

(i) How would you define the terms atomic mass and molecular mass ? (i

1.	(i) How would you define the terms atomic mass and molecular mass ? (ii) Nitrogen occurs in nature in the form of two isotopes with atomic masses 14 and 15 respectively. If the average atomic mass of nitrogen is 14.0067, what is the percent abundance of the two isotopes ?
Answer» Solution :(ii) Suppose the percentage of `N^(14)`isotope is x `therefore` The percentage of `N^(15) = 100-x` The AVERAGE ATOMIC mass of nitrogen is 14.0067 `therefore 14.0067 = ((14 xx x) + 15(100-x))/100` which GIVES `x=99.33` Hence, the abundance of `N^(14)` isotope is 99.33% while that of `N^(15)` isotope is: `=10099.33 = 0.67 %`