Final answer:
The chemical equation AgI + Na₂S → Ag₂S + NaI is balanced by placing a coefficient of 2 in front of AgI and NaI to ensure that both the number of atoms and the charges are balanced on each side of the equation, resulting in 2AgI + Na₂S → Ag₂S + 2NaI.
Step-by-step explanation:
To balance the chemical equation AgI + Na₂S → Ag₂S + NaI, we need to ensure that there are equal numbers of each type of atom on both sides of the reaction. Looking at the unbalanced equation, we have an imbalance in the number of Ag (silver) atoms. Currently, there is 1 Ag atom on the reactant side (within AgI) and 2 Ag atoms on the product side (within Ag₂S). To balance this, we need to multiply AgI by 2 on the reaction side:
Step 1: Balance Ag (silver)
2AgI + Na₂S → Ag₂S + NaI
Step 2: Balance Na (sodium) and I (iodine)
We now have 2 I atoms on the reactant side, which means we need 2 NaI on the product side to balance iodine:
2AgI + Na₂S → Ag₂S + 2NaI
Step 3: Final Check
Now the equation is balanced: We have 2 Ag atoms, 2 I atoms, and 1 S atom on both sides. As for the sodium atoms, there are 2 on the reactant side (within Na₂S) and 2 on the product side (within 2NaI).
Therefore, the balanced equation is:
2AgI + Na₂S → Ag₂S + 2NaI