Question

hydrogen is found primarily as two isotopes in nature: (1.0078u) and (2.0140u). Caluclate the percentage abundance of each isotope based on hydrogens average atomic mass

Answer 1

hydrogens average atomic mass = 1,01u

x = isotope about mass (1.0078u)
y = isotope about mass (2.0140u)

x + y = 100%
so:
x = 100% - y


`hydrogens ~average~atomic~mass=((1.0078\cdot x)+(2.0140\cdot y))/(100)\\ 1.01=((1.0078\cdot (100-y))+(2.0140y))/(100)||\cdot 100\\ 101=100.78-1.0078y+2.0140\\ 101-100.78=1.0062y\\ 0,22=1.0062y||:1.0062\\ 0.219\%=y\\\\ x=100\%-y\\ x=100\%-0.219\%\\ x=99.781\%\\\\`

answer:

`x=99.781\%\\ y=0.219\%`