Question

Calculate the number of moles for each compound in the following table.

Compound	Mass	Moles
Magnesium phosphate	326.4 g
Calcium nitrate	303.0 g
Potassium chromate	141.6 g
Dinitrogen pentoxide	406.3 g

Short answer

The number of moles for each compound in the following table,

Compound	Mass	Moles
Magnesium phosphate	326.4 g	1.24mol
Calcium nitrate	303.0 g	1.84mol
Potassium chromate	141.6 g	0.729mol
Dinitrogen pentoxide	406.3 g	3.76mol

Step-by-step solution

Definition

Themolar mass of a material is defined asthe mass of the substancecontained in one moleof the substance, and it isequal to the total mass of the component atoms. It may be stated mathematically as follows:
Molar mass =$\frac{WeightinG}{N0.ofmoles}$$\frac{Weighting}{numberofmole}$

Determination of mole of Magnesium phosphate

i)

Magnesium phosphatehas the molecular formula and a molar mass of 262.8577 g/mole. With a mass of 326.4g,

$\begin{array}{rcl}Mole& =& \frac{326.4g}{262.85{\displaystyle \raisebox{1ex}{$g$}\!\left/ \!\raisebox{-1ex}{$mol$}\right.}}\\ & =& 1.24mol\end{array}$

Determination of mole of Calcium nitrate

ii18=\Calcium nitratehas the molecular formula and a molar massof 164.088g/mole. With a mass of 303.0g,

$\begin{array}{rcl}Mole& =& \frac{303g}{164.088{\displaystyle \raisebox{1ex}{$g$}\!\left/ \!\raisebox{-1ex}{$Mol$}\right.}}===\\ & =& 1.84mol\end{array}$

Determination of mole of Potassium chromate

iii)

Potassium chromate has the molecular formula K₂CrO₄ and a molar mass of 194.189g/mole. With a mass of 141.6g,

$\begin{array}{rcl}Mole& =& \frac{141.6g}{194.189{\displaystyle \raisebox{1ex}{$g$}\!\left/ \!\raisebox{-1ex}{$mol$}\right.}}\\ & =& 0.729mol\end{array}$

Determination of mole of Dinitrogen pentaoxide

iv)

Dinitrogen pentoxidehas the molecular formula N₂O₅ and a molar massof 108.01g/mole. With a mass of 406.3g,

$\begin{array}{rcl}Mole& =& \frac{406.3g}{108.01{\displaystyle \raisebox{1ex}{$g$}\!\left/ \!\raisebox{-1ex}{$mol$}\right.}}\\ & =& 3.76mol\end{array}$

Therefore, the number of moles for each compound is,

1. Mg₃(PO₄)₂ is 1.24mol
2. Ca(NO₃)₂ is 1.84mol
3. K₂CrO₄ is 0.729mol
4. N₂O₅ is 3.76mol