Question

What is the mass of $10$ moles of Sodium sulphite $\left({\mathrm{Na}}_2{\mathrm{SO}}_3\right)$?

Answer 1

Given:

Moles of Sodium sulphite $\left({\mathrm{Na}}_2{\mathrm{SO}}_3\right)$ $=10\mathrm{mol}$

Step 1. Formula for the number of moles:

$\text{Number of moles}=\frac{\text{Mass}}{\text{Molar mass}}$------------------------------------(I)

Step 2. Calculation of molar mass of Sodium sulphite:

Molar mass of Sodium sulphite $\left({\mathrm{Na}}_2{\mathrm{SO}}_3\right)$$=$$\text{(2×Atomic mass of sodium)+(1×Atomic mass of sulphur)+(3×Atomic mass of oxygen)}$

$=$$\left[\right(2\times 23)+(1\times 32)+(3\times 16\left)\right]{\text{g mol}}^{-1}{\text{=126 g mol}}^{-1}$

Step 3. Calculation of mass of Sodium sulphite:

Substituting the values in equation (I), we get

$$\begin{gathered} 10\hspace{0.17em}\text{mol}=\frac{\text{Mass}}{126{\text{g mol}}^{-1}} \\ \text{Mass =126×10 g}=1260\text{g} \end{gathered}$$

Hence, the mass of $10$ moles of Sodium sulphite is $1260\text{g}$.