Question

A 0.700 g unknown mixture with CaCl2 reacts with aqueous sodium phosphate to give 0.425 g Ca3(PO4)2. Show calculation for the percentage CaCl2?

Answer 1

The percentage CaCl₂ : 65.14%

Further explanation

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.

Reaction

3CaCl₂+2Na₃PO₄⇒Ca₃(PO₄)₂ + 6NaCl

mol Ca₃(PO₄)₂(MW=310.18 g/mol) :

`\tt (0.425)/(310.18)=0.00137`

mol ratio CaCl₂ : Ca₃(PO₄)₂ = 3 : 1, so mol CaCl₂ :

`\tt (3)/(1)* 0.00137=0.00411`

mass CaCl₂ (MW=110.98 g/mol) :

`\tt 0.00411* 110.98=0.456~g`

The percentage CaCl₂ :

`\tt \%CaCl_2~in~mixture=(0.456)/(0.7)* 100\%=65.14\%`