Question

Hydrogen and chlorine atoms react to form a simple diatomic molecule in a 1:1 ration, that is HCl. The percent isotopic abundances of the chlorine isotopes 35Cl and 37Cl are 75.77% and 24.23%, respectively. The percent isotopic abundances of the hydrogen isotopes are 2H and 3H are 0.015% and 0.001%. (a) How many different HCl molecules are possible, and what are their mass numbers

Answer 1

Four different HCl molecules are possible.

1. Mass of
   `^(2)H^(35)Cl` = 37 amu
2. Mass of
   `^(3)H^(35)Cl` = 38 amu
3. Mass of
   `^(2)H^(37)Cl` = 39 amu
4. Mass of
   `^(3)H^(37)Cl` = 40 amu

Step-by-step explanation:

Mass of 2-H isotope = 2 amu

Mass of 3-H isotope = 3 amu

Mass of 35-Cl isotope = 35 amu

Mass of 37-Cl isotope = 37 amu

Different HCl molecules possible are:

1)
`^2H+^(35)Cl\rightarrow ^(2)H^(35)Cl`

Mass of
`^(2)H^(35)Cl` = 2 amu + 35 amu = 37 amu

2)
`^3H+^(35)Cl\rightarrow ^(3)H^(35)Cl`

Mass of
`^(3)H^(35)Cl` = 3 amu + 35 amu = 38 amu

3)
`^2H+^(37)Cl\rightarrow ^(2)H^(37)Cl`

Mass of
`^(2)H^(37)Cl` = 2 amu + 37 amu = 39 amu

4)
`^3H+^(37)Cl\rightarrow ^(3)H^(37)Cl`

Mass of
`^(3)H^(37)Cl` = 3 amu + 37 amu = 40 amu