0.4 mole of orthophosphoric acid and 1.0 mole of calcium hydroxide were allowed to react. Calculate the maximum number of moles of calcium phosphate formed. 

Explanation

The stoichiometric equation of
`3Ca(OH)_(2)+2H_(3)PO_(4) to Ca_(3)(PO_(4))_(2)+3H_(2)O`
3 moles of `Ca(OH)_(2)="2 moles of "H_(3)PO_(4)`
1 mole of `Ca(OH)_(2)="0.67 mole of "H_(3)PO_(4)`
0.6 mole of `Ca(OH)_(2)="0.4 mole of "H_(3)PO_(4)`
`H_(3)PO_(4)` is the limiting regent. Hence, salt formed is dependent on the availability of acid only.
2 moles of `H_(3)PO_(4)="1 mole of "Ca_(3)(PO_(4))_(2)`
0.4 moles of `H_(3)PO_(4)=?`
Number of moles of calcium phosphate formed `=0.4 xx 1/2=0.2"mole"`