Reverse the reactions. Label the acids and bases on the left-hand side of each of the reversed equations?

1. HCl + NH3 => NH4+ + Cl-
2.NH3 + H2O => NH4+ +OH-
3. HCl +H2O => H3O+ +Cl-
4. H3PO4 +H20 => HPO4^-2 +H3O+
5.H2PO4- +H2O => HPO4^-2 +H3O+

NH4^+ + Cl^- ==> NH3 + HCl

The acid is the one with more H. The base is the one with fewer H.
NH4^+ is the acid on the left; NH3 is the conjugate base on the right.
Cl^- is the base on the left; HCl is the conjugate acid on the right.

To reverse a chemical reaction, you need to switch the positions of the reactants and products. Let's go through each reaction and reverse them.

1. HCl + NH3 ⇌ NH4+ + Cl-
Reversed: NH4+ + Cl- ⇌ HCl + NH3
The acid on the left-hand side is NH4+, and the base is Cl-.

2. NH3 + H2O ⇌ NH4+ + OH-
Reversed: NH4+ + OH- ⇌ NH3 + H2O
The acid on the left-hand side is NH4+, and the base is OH-.

3. HCl + H2O ⇌ H3O+ + Cl-
Reversed: H3O+ + Cl- ⇌ HCl + H2O
The acid on the left-hand side is H3O+, and the base is Cl-.

4. H3PO4 + H2O ⇌ HPO4^-2 + H3O+
Reversed: HPO4^-2 + H3O+ ⇌ H3PO4 + H2O
The acid on the left-hand side is HPO4^-2, and the base is H3O+.

5. H2PO4- + H2O ⇌ HPO4^-2 + H3O+
Reversed: HPO4^-2 + H3O+ ⇌ H2PO4- + H2O
The acid on the left-hand side is HPO4^-2, and the base is H3O+.

Remember that acids donate protons (H+) and bases accept protons in a chemical reaction. By reversing the reaction, the acid becomes the product and the base becomes the reactant on the left-hand side of the equation.