91Ó°ÊÓ

The mass of a compound can be used for the determination of molecular ions.

The molecular weight of a compound is similar to the mass value of a molecular ion.

a. The molecules ${\text{C}}_{\text{8}}{\text{H}}_{\text{6}}$and ${\text{C}}_{\text{6}}{\text{H}}_{\text{14}}\text{O}$possess molecular mass 102. It can be calculated as-

The molecular mass of ${\text{C}}_{\text{8}}{\text{H}}_{\text{6}}$is$12×8+1×6=102$

The molecular mass of ${\text{C}}_{\text{6}}{\text{H}}_{\text{14}}\text{O}$is $12×6+1×14+16=102$

b. The molecules ${\text{C}}_{\text{8}}{\text{H}}_{\text{2}}$and ${\text{C}}_{\text{7}}{\text{H}}_{\text{14}}$possess molecular mass 98. It can be calculated as-

The molecular mass of ${\text{C}}_{\text{8}}{\text{H}}_{\text{2}}$is $12×8+1×2=98$

The molecular mass of ${\text{C}}_{\text{7}}{\text{H}}_{\text{14}}$is $12×7+1×14=98$

c. The molecules ${\text{C}}_{\text{8}}{\text{H}}_{\text{9}}\text{N}$and ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{N}}_{\text{3}}$possess molecular mass 119. It can be calculated as-

The molecular mass of ${\text{C}}_{\text{8}}{\text{H}}_{\text{9}}\text{N}$is $12×8+1×9+14=119$

The molecular mass of ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{N}}_{\text{3}}$is $12×6+1×5+14×3=119$

d. The molecules ${\text{C}}_{\text{6}}{\text{H}}_{\text{2}}$and ${\text{C}}_{\text{4}}{\text{H}}_{\text{10}}\text{O}$or ${\text{C}}_{\text{3}}{\text{H}}_{\text{6}}{\text{O}}_{\text{2}}$possess molecular mass 74. It can be calculated as-

The molecular mass of ${\text{C}}_{\text{6}}{\text{H}}_{\text{2}}$is $12×2+2×1=74$

The molecular mass of ${\text{C}}_{\text{4}}{\text{H}}_{\text{10}}\text{O}$ is $12×4+1×10=74$

The molecular mass of ${\text{C}}_{\text{3}}{\text{H}}_{\text{6}}{\text{O}}_{\text{2}}$is $12×3+1×6+16×2=74$