Explanation:
The limiting reagent is the reactant that is totally consumed when the reaction is complete.
The given reaction is
[tex]H_{3}PO_{4}+3NaOH[/tex]→[tex]Na_{3}PO_{4}+H_{2}O[/tex]
The reaction says that every mole of [tex]H_{3}PO_{4}[/tex] requires [tex]3[/tex] moles of [tex]NaOH[/tex].
Given that number of moles of [tex]H_{3}PO_{4}[/tex] is [tex]7.5[/tex]
So,[tex]3\times 7.5=22.5[/tex] moles of [tex]NaOH[/tex] is required.
But only [tex]15[/tex] moles of [tex]NaOH[/tex] is available.
This means that [tex]NaOH[/tex] will be completely consumed.
So,[tex]NaOH[/tex] is the limiting reagent.
