Number of moles is mathematically expressed as,
![\frac{\text{Weight of solute (g)}}{\text{gram molecular weight}}](https://img.qammunity.org/2019/formulas/chemistry/high-school/jme69y0ushj33phgma4asv54y8d3gqm6p4.png)
......(1)
Thus, for estimating number of moles, one need to know weight of solute and molecular weight.
Now, if one measure the volume of solid and density of solid is know, then one can employ following formula for estimating weight of solid:
Weight of solid = Volume of solid x Density
On substituting the obtained weight of solid in Eq. 1, one can obtain number of moles of solid.