Answer:
2 NaI ---> 2 Na + I₂
Explanation:
The only way the reactant NaI can decompose is by separating into 2 atoms, Na and I. However, you must take into account that iodine (I) exists as a diatomic molecule.
An equation is balanced when there is an equal amount of each element on both sides of the reaction. These amounts can be modified by adding coefficients in from of the molecules/atoms.
The unbalanced equation:
NaI -----> Na + I₂
Reactants: 1 sodium, 1 iodine
Products: 1 sodium, 2 iodine
The balanced equation:
2 NaI ---> 2 Na + I₂
Reactants: 2 sodium, 2 iodine
Products: 2 sodium, 2 iodine
