Question

and copper (ii) chloride mixed and reacted. the results were a clumpy olive green solution. the mass was taken again. the results are pictured below.
before reaction
after reaction
which of the following is the correctly balanced equation for the reaction in the copper (ii) chloride double replacement described experiment above?
3 cucl₂ (aq) + 2 na₃po₄ (aq) -> cu₃(po₄)₂ (s) + 6 nacl (aq)
cu₂cl (aq) + na₃po₄ (aq) -> cu₂po₄ (s) + 3 nacl (aq)
2 cucl₂ (aq) + na₃po₄ (aq) -> cu₂po₄ (s) + 3 nacl₂ (aq)
cu₂cl (aq) + 2 na₃po₄ (aq) -> cu₃(po₄)₂ (s) + na₃cl (aq)

Explanation:

Step1: Identify correct reactant formula

Copper (II) chloride is $\text{CuCl}_2$ (since $\text{Cu}^{2+}$ pairs with 2 $\text{Cl}^-$). This eliminates options with $\text{Cu}_2\text{Cl}$.

Step2: Balance copper atoms

Left side: 3 $\text{CuCl}_2$ gives 3 $\text{Cu}^{2+}$. Right side: $\text{Cu}_3(\text{PO}_4)_2$ has 3 $\text{Cu}^{2+}$.

Step3: Balance phosphate atoms

Right side: $\text{Cu}_3(\text{PO}_4)_2$ has 2 $\text{PO}_4^{3-}$. Left side: 2 $\text{Na}_3\text{PO}_4$ gives 2 $\text{PO}_4^{3-}$.

Step4: Balance sodium atoms

Left side: 2 $\text{Na}_3\text{PO}_4$ gives 6 $\text{Na}^+$. Right side: 6 $\text{NaCl}$ gives 6 $\text{Na}^+$.

Step5: Balance chlorine atoms

Left side: 3 $\text{CuCl}_2$ gives 6 $\text{Cl}^-$. Right side: 6 $\text{NaCl}$ gives 6 $\text{Cl}^-$.
All atoms are balanced in this equation.

Answer:

A. $3\text{CuCl}_2\text{ (aq)} + 2\text{Na}_3\text{PO}_4\text{ (aq)}
ightarrow \text{Cu}_3(\text{PO}_4)_2\text{ (s)} + 6\text{NaCl (aq)}$