Final answer:
The stoichiometric coefficient for potassium nitrate in the reaction Co(NO₃)₃ + K₂S cannot be determined without a complete and balanced equation. Spectator ions are those that remain unchanged in a reaction and are not involved in the chemical change.
Step-by-step explanation:
When considering the molecular reaction Co(NO₃)₃ + K₂S, the correct stoichiometric coefficient for potassium nitrate (KNO₃) is not derivable from the provided equation as it is neither complete nor balanced as given. To balance the equation, first, we would need to determine the products of the reaction between cobalt(III) nitrate and potassium sulfide. Typically, a double displacement reaction would occur, forming potassium nitrate and cobalt(III) sulfide. After establishing the correct products and balancing the equation, we could then identify the stoichiometric coefficient of potassium nitrate.
As for spectator ions, these are ions that appear unchanged on both the reactant and product sides of a complete ionic equation. They do not participate in the actual chemical reaction and can be removed when writing the net ionic equation. To identify spectator ions, the reaction needs to be represented as a complete ionic equation first.