To balance a double replacement reaction, just follow these easy steps:

1. Write the unbalanced equation: Let's say we have sodium sulfate mixed with barium chloride. We start with: $\text{Na}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + \text{NaCl}$

2. List the reactants and products: Look at all the compounds we have. We have:

   • Sodium sulfate
   • Barium chloride
   • Barium sulfate
   • Sodium chloride

3. Count atoms of each element: Count how many atoms of each element are on both sides of the equation.

4. Adjust coefficients: Start by balancing the most complicated molecule first. For our example, when we adjust, we get: $\text{Na}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + 2 \text{NaCl}$

5. Double-check counts: Make sure the number of atoms for each element is the same on both sides.

6. Finalize: Once everything is balanced, your equation is complete! In this case, both reactants create two units of sodium chloride while keeping barium and sulfate in balance.