Question

What is the actual molecular mass of chlorine?

Answer 1

Molecular mass

• Determine the molecule's formula.
• Determine the atomic mass of each element in the molecule using the periodic table.
• Multiply the atomic mass of each element by the number of atoms in the molecule.
• The subscript adjacent to the element symbol in the molecular formula represents this number.
• For each atom in the molecule, add these values together.

Calculate the actual molecular mass of chlorine

• The formula for molecular mass is as follows:

$\mathrm{Molecular}\mathrm{mass}=\mathrm{Number}\mathrm{of}\mathrm{atoms}\times \mathrm{Atomic}\mathrm{mass}$

• Atomic mass of one atom of chlorine is $35.453\mathrm{amu}$.
• Chlorine exists as a diatomic molecule that is ${\mathrm{Cl}}_2$.
• The molecular mass of ${\mathrm{Cl}}_2$ is as follows:

$\begin{array}{rcl}\mathrm{Molecular}\mathrm{mass}& =& 2\times 35.453\mathrm{amu}\\ & =& 70.906\mathrm{amu}\end{array}$

• $1\mathrm{amu}=1.66\times {10}^{-24}\mathrm{g}$
• The actual molecular mass of ${\mathrm{Cl}}_2$ is as follows:

$\begin{array}{rcl}\mathrm{Actual}\mathrm{molecular}\mathrm{mass}\mathrm{of}{\mathrm{Cl}}_2& =& 70.906\times 1.66\times {10}^{-24}\mathrm{g}\\ & =& 177.7\times {10}^{-24}\mathrm{g}\end{array}$

• Therefore, the actual molecular mass of chlorine is $\begin{array}{rcl}& & 177.7\times {10}^{-24}\mathrm{g}\end{array}$.