Answer
$$(NH_4)_2SO_4(aq) + Ca(OH)_2(aq) \longrightarrow 2NH_3(g) + 2H_2O(l) + CaSO_4(aq)$$
Work Step by Step
1. This reaction has an ammonium ion and a base in its reactants. Thus, it will produce $NH_3(g)$, $H_2O(l)$ and a salt made of the other ions:
$$(NH_4)_2SO_4(aq) + Ca(OH)_2(aq) \longrightarrow NH_3(g) + H_2O(l) + Salt$$
The remaining ions are: $Ca^{2+}$ and $S{O_4}^{2-}$, therefore, the salt is $CaSO_4$:
$$(NH_4)_2SO_4(aq) + Ca(OH)_2(aq) \longrightarrow NH_3(g) + H_2O(l) + CaSO_4(aq)$$
2. Now, balance the equation.
To balance the number of nitrogen atoms, put a $2$ before $NH_3$:
$$(NH_4)_2SO_4(aq) + Ca(OH)_2(aq) \longrightarrow 2NH_3(g) + H_2O(l) + CaSO_4(aq)$$
To balance the number of oxygen atoms, do the same for $H_2O$:
$$(NH_4)_2SO_4(aq) + Ca(OH)_2(aq) \longrightarrow 2NH_3(g) + 2H_2O(l) + CaSO_4(aq)$$
- The equation is balanced.
