Question

9. Write the correct chemical formulas and balance the following equations: A. Potassium iodide plus calcium arsenate yields calcium iodide plus potassium arsenate.

Answer 1

Q9. (A.) potassium iodide = KI

calcium arsenate = Ca₃(AsO₄)₂

calcium iodide = CaI₂

potassium arsenate = K₃AsO₄

The unbalanced equation is : KI + Ca₃(AsO₄)₂$\rightarrow$ CaI₂ + K₃AsO₄

There are 3 Ca atoms in reactant side but only 1 Ca atom in product side. Multiply CaI₂ by 3

improved equation 1 : KI + Ca₃(AsO₄)₂$\rightarrow$ 3 CaI₂ + K₃AsO₄

Now there are 6 iodine atoms in product side but only one iodine atom in reactant side. Multiply KI by 6

improved equation 2 : 6 KI + Ca₃(AsO₄)₂$\rightarrow$ 3 CaI₂ + K₃AsO₄

Now there are 6 K atoms in reactant side but only 3 K atoms in product side. Multiply K₃AsO₄ by 2

improved equation 3 : 6 KI + Ca₃(AsO₄)₂$\rightarrow$ 3 CaI₂ + 2 K₃AsO₄

Now all atoms are balanced.

The balanced equation is : 6 KI + Ca₃(AsO₄)₂$\rightarrow$3 CaI₂ + 2 K₃AsO₄