Answer
Step-by-step explanation
In the oxidation number method of balancing chemical equations, you determine the oxidation numbers of all atoms. Then you multiply the atoms that have changed by small whole numbers. You are making the total loss of electrons equal to the total gain of electrons. Then you balance the rest of the atoms.
The given equation is:
Ag + H₂S + O₂ —> Ag₂S + H₂O
Step 1. Identify the atoms that change oxidation number.
Left hand side: Ag = 0, H = +1, S = -2, O = 0
Right hand side: Ag = +1, S = -2, H = +1, and O = -2
The changes in oxidation number are:
Ag: 0 → +1; Change = +1
O: 0 → -2; Change = -2
Step 2. Equalize the changes in oxidation number.
Each Ag atom has lost one electron, and each O atom has gained two electrons.
O: 0 → -2; Change = -2,