In this lab, double replacement reactions between compounds were done in order to determine the equation and description of a new substance. During the lab, each participant was given drop bottles, spot plates. The drop bottles contained different compounds which were dropped into the spot plates and mixed together. Compounds were combined together and would generally form a completely different looking substance. Droplets of reactants such as BaCl2 and Na2SO4 were dropped into spot plates, which created a double replacement reaction. If the substance no longer had an aqueous solution after the double replacement, then the substance would be a precipitate. A precipitate is when two aqueous solutions are combined together to form a solid product through double replacement reactions. These tests were done to give students a better understanding of double replacement reactions.
The purpose of this lab was to observe the results of many double replacement reactions, as well as to practice writing non-ionic, complete ionic, and net ionic equations for precipitation reactions.
A good test to determine the presence of chloride ions in a water sample would be to have them react with silver ions. This is due to the fact that on the solubility charts, chloride and silver ions form a precipitate, meaning that together they have low solubility, and form a solid substance. With the product of silver and chloride ions, the presence of the chloride ion will be very evident as it is a solid substance. If chloride ions were combined with sulphate ions which they are soluble with, then their presence would be nowhere near as clear. This is because the chloride ions would have an aqueous solution.
A good test to determine the presence of silver ions in a water sample would be to pair it with bromide ions. These two ions combined together, would form a precipitate, which would help clearly show the presence of silver in the substance. Silver and Bromide Ions combined together have a low solubility which allows for it to be a precipitate. For example, Silver ions are soluble with Fluoride ions, which would only create an aqueous solution, and the presence of silver ions would not be as evident as they would be if they were paired with Bromide Ions.