Equilibrium and Le'Chatlier's Principle
You would see a picture like this
and you might write something like the following in your notebook or on your data sheet:
System: AgCl system
Stress Applied: added NH3
Observations: The addition of NH3 solution caused the white precipitate of AgCl to disappear.
Chemical Explanation: The addition of NH3 decreased the concentration of free silver ions in solution. This decreased the rate of the forward reaction. As a result the equilibrium shifted to the left. In doing so more AgCl precipitate dissolved.