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) :
[tex]\tt=\dfrac{22.44}{199,89}=0.112[/tex]
mass of Na₃PO₄ = 16.85 g
mol of Na₃PO₄ (MW=163,94 g/mol) :
[tex]\tt =\dfrac{16.85}{163,94}=0.103[/tex]
mol ratio of reactants (to find limiring reactant): CaBr₂ : Na₃PO₄ =
[tex]\tt \dfrac{0.112}{3}\div \dfrac{0.103}{2}=0.0373\div 0.0515\rightarrow CaBr_2~limiting~reactant(smaller~ratio)[/tex]
So the excess = Na₃PO₄
mol Na₃PO₄ reacted :
[tex]\tt \dfrac{2}{3}\times 0.112=0.0746[/tex]
mol Na₃PO₄ unreacted :
[tex]\tt 0.103-0.0746=0.0284[/tex]
Mass Na₃PO₄ :
[tex]\tt 0.0284\times 163.94=4.656~g[/tex]
