Question

predict the products of the double replacement reactions given. check to see that the equations are balanced.
$agno_3 + nacl \to ?$
$agna + clno_3$
$nano_3 + agcl (s)$
$2nano_3 + 3agcl (s)$
$ag + nano_3$
$bacl_2 + mgso_4 \to ?$
$bamg + clso_4$
$ba(so_4)_2 (s) + mgcl$
$ba + mg + cl_2$
$baso_4 (s) + mgcl_2$
complete
done

Explanation:

Step1: Identify cation/anion pairs

Reactants: $\text{BaCl}_2$ (cation $\text{Ba}^{2+}$, anion $\text{Cl}^-$); $\text{MgSO}_4$ (cation $\text{Mg}^{2+}$, anion $\text{SO}_4^{2-}$)

Step2: Swap pairs for double replacement

New pairs: $\text{Ba}^{2+}$ with $\text{SO}_4^{2-}$; $\text{Mg}^{2+}$ with $\text{Cl}^-$

Step3: Form neutral compounds

$\text{BaSO}_4$ (insoluble solid, s); $\text{MgCl}_2$ (soluble)

Step4: Balance the equation

$\text{BaCl}_2 + \text{MgSO}_4
ightarrow \text{BaSO}_4 \text{(s)} + \text{MgCl}_2$ (already balanced)

Answer:

$\text{BaSO}_4 \text{(s)} + \text{MgCl}_2$ (corresponding to the fourth option)