Question

What is the molar mass of sodium phosphate?

Answer 1

Hint: Molecular mass is the sum of the atomic masses of all atoms in a molecule. Therefore, we can calculate the molecular mass if we know the molecular formula which can be given and can also be calculated.

Complete step by step answer:
For calculating the molecular mass of any molecule first we need to know the molecular formula of that molecule. If the molecular formula is not given we can anytime make the molecular formula in the following way:
Step I: We should first know the symbol of the atoms used. In this it is Sodium that is Na and oxide meaning phosphate that is P.
Step II: Write the symbols below their names as shown
$\text{Sodium Phosphate}$
${Na \;\;\;\;\;\;\;\;\;\;\;\; PO_4}$
Step III: Write the valency of the atom below as shown
$\text{Sodium Phosphate}$
${ Na \;\;\;\;\;\;\;\;\;\;\;\; P{{O}_{4}}}$
$\text{1 3}$
Step IV: Now cross multiply the valency here we will get $N{{a}_{3}}P{{O}_{4}}$.
For molecular mass,
To calculate the molecular mass first we should know the atomic mass of all the atoms here we have sodium and oxygen
We know the atomic mass of sodium is $23gm$
and the atomic mass of phosphate is $95gm$.
Now multiply the atomic mass by the number of atoms of each atom and add to make the molecule and hence the molecular formula, as show below for the given question
$\begin{align}
  & 3(Na)+(P{{O}_{4}}) \\
 & 3(23)+(95) \\
 & 69+95 \\
 & 164gm \\
\end{align}$
Therefore the molecular mass of sodium phosphate is $164gm$.

Note: The molecular formula, atomic masses of each atom and other required things can be given and be calculated. Also, it is advised to know the atomic mass of most of the elements and most importantly can also of those which are most common.