What is the difference between aqueous and a liquid when you are writing equations?

Answer 1

When something is defined as aqueous (aq) in a chemical equation, it refers to that particular reagent being present as a water solution. When something is defined as a liquid (l), it means the reagent is its pure substance in the liquid state. So with aqueous reagents in a reaction, you have to assume that water is added onto that reagent. This means it might have an outcome in the reaction that is different than what it would be when its just the reagent alone. Most of the time, aqueous states of a reagent will yield different products than the liquid form of it alone.