A mixture of 22.44 g of CaBr2 and 16.85 g Na3PO4 is used in the following reaction. Determine the mass of the excess reactant left unreacted. 3 CaBr2 + 2 Na3PO4 --> Ca3(PO4)2 + 6NaBr

The mass of the excess reactant left unreacted : 4.656 g

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

The reaction coefficient in a chemical equation shows the mole ratio of the reactants and products

Reaction

3 CaBr₂ + 2 Na₃PO₄ --> Ca₃(PO₄)₂ + 6NaBr

mass of CaBr₂ = 22.44 g

mol of CaBr₂(MW=199,89 g/mol) :

mass of Na₃PO₄ = 16.85 g

mol of Na₃PO₄ (MW=163,94 g/mol) :

mol ratio of reactants (to find limiring reactant): CaBr₂ : Na₃PO₄ =

So the excess =  Na₃PO₄

mol Na₃PO₄ reacted :

mol  Na₃PO₄ unreacted :

Mass  Na₃PO₄ :