Question

How many moles of magnesium phosphate $M{g}_3{\left(P{O}_4\right)}_2$ will contain 0.25 mole of oxygen atoms?

Answer 1

Hint:Magnesium phosphate has 3 moles of magnesium, two moles of phosphorus and eight moles of oxygen atom in its chemical formula. Because there are three magnesium atoms, two phosphorus atoms and eight oxygen atoms in magnesium phosphate molecules.

Complete step-by-step answer:- In the question it is asked to find how many moles of magnesium sulphate contains 0.25 moles of oxygen.
- As per the molecular formula of magnesium phosphate ($M{g}_3{\left(P{O}_4\right)}_2$) it contains 3 moles of magnesium, two moles of phosphorus and eight moles of oxygen atoms.
- Means one moles of magnesium phosphate contains 8 moles of oxygen atoms.
- Then how many moles of magnesium phosphate contain 0.25 moles of oxygen.
 $$\begin{gathered} \text{8 moles of oxygen}\to \text{one mole of magnesium phosphate } \\ \text{0}\text{.25 moles of oxygen is present }\to \text{?} \\ {\displaystyle \frac{0.25}{8}}\times 1=0.03125moles \end{gathered}$$
- Therefore 0.03125 moles of magnesium sulphate contains 0.25 moles of oxygen.

Additional information:
- The oxidation state of magnesium in magnesium phosphate is +2.
- Each phosphate has four oxygen atoms, meaning there are two phosphates there in the magnesium phosphate.
- Means there are eight oxygen atoms present in one moles of magnesium phosphate.
- Magnesium phosphate molecular formula is going to resemble $A_3{B}_2$ . Here A = magnesium and B = phosphate ion.

Note:We have to count the number of moles of a particular atom present in the given molecular formula. If we know about them exactly we can calculate the number of moles of each reactant that is going to be involved in the chemical reaction.