Cu₂S + 2O₂ → 2Cu₂O + SO₂

Here's how we balance it:

1. Identify the elements: We have copper (Cu), sulfur (S), and oxygen (O).

2. Count atoms on each side:

* Reactants: 2 Cu, 1 S, 4 O

* Products: 4 Cu, 1 S, 3 O

3. Balance Cu: There are 2 Cu atoms on the left and 4 on the right. Multiply Cu₂O by 2 on the product side.

* Reactants: 2 Cu, 1 S, 4 O

* Products: 4 Cu, 1 S, 5 O

4. Balance O: There are 4 O atoms on the left and 5 on the right. Multiply O₂ by 2 on the reactant side.

* Reactants: 2 Cu, 1 S, 6 O

* Products: 4 Cu, 1 S, 5 O

5. Balance O again: Now we have 6 O atoms on the left and 5 on the right. We need to adjust the products. Multiply SO₂ by 1 on the product side.

* Reactants: 2 Cu, 1 S, 6 O

* Products: 4 Cu, 1 S, 6 O

Now the equation is balanced.