![]() ![]() ⑤ All compounds that contain a sulfate ion are soluble except those that contain Ba2+, Sr2+, or Pb2+. ④ All compounds that contain a group VII element (halogen) are soluble except those that contain Ag+, Hg+, or Pb2+. ③ All compounds that contain a nitrate ion or acetate ion are soluble. ② All compounds that contain an ammonium ion are soluble. ① All compounds that contain a group I element (alkali metal) are soluble. Generally, for inorganic compounds like the ones used in the experiment, the solubility rules are as written below. These are rules that provide tell us which ions form solids, and which remain in their ionic form in an aqueous solution. Whether or not a reaction will form a precipitate is dictated by the solubility rules. no change (no precipitate): Na2CO3 (aq) + KI (aq) Ii) Result of Mixing Two Solutions (based on the formation and color of the precipitate) Solution ⑧ Observe if there are any changes made in the solutions after mixing. ⑦ Perform the required 14 experiments of mixing two solutions in this way, but by using different variables. Do not shake it too hard, as it may result in a leakage of the mixed solution that could cause an error in the result. ⑥ Gently shake the test tube so that two solutions would mix evenly. ⑤ Make sure to use a different spuit to mix a second solution to the one already in the test tube. Using a spuit, put approximately 1~3 drop of a solution in the test tube, and try not to make the spuit touch the inside of the test tube. ![]() ④ One experiment will involve the mixing of two solutions. Put them in 6 separate Erlenmeyer flasks- one flask for each solution. ③ Prepare the required 6 solutions that are to be involved in the experiment. ② Place the test tubes in the spaces of the test tube rack, one in each square section. (*During this step, make sure that the inner sides of all test tubes are dried.) ① Prepare 5 test tubes for mixing solutions, and wash each of them with distilled water so that impurities will not get involved in the experiment. Equipment: 5 test tubes, a test tube rack, 6 Erlenmeyer flasks, 6 spuits, a bottle of distilled water, spare beaker Chemicals to prepare: Na2CO3 (aq), BaCl2 (aq), KI (aq), Pb(NO3)2 (aq), CuSO4 (aq), NaOH (aq) We decided to investigate more detailed and specific facts through the process below. For example, an experiment involving the element Cu may have a blue precipitate. We also thought that among the ones forming a solid, not all would have the same color. Some might just turn out as a mixture of two liquids, while some might form solids along the process. Consequently, a precipitation reaction would be able to be expressed as a chemical equation, and also a net ionic equation after eliminating the spectator ions from both sides of the equation.īefore the experiment, our group first predicted that not all 14 experiments would create precipitates. ![]() Precipitation reactions usually involve ionic compounds, and although all ionic compounds are strong electrolytes they are not equally soluble. Whether a precipitate, an insoluble solid that separates from the solution, will form depends on the solubility of the solute. As a result of all experiments, it would be able to infer how the solubility rules could be used to explain the products of each precipitation reaction.Ī precipitation reaction results in the formation of an insoluble product. In chemistry, this is referred to as a ‘precipitate’, and the whole phenomenon as such is called a ‘precipitation reaction’. The change here does not indicate just a change in color, but whether a solid sediment would form or not. The following experiments were carried out in order to detect which two solutions would create a distinguishable change when mixed. ‘Solubility Rules and Precipitation Reactions’ ![]() It was done in June, a few weeks before our final exams. During the first semester of my freshmen year, I had to hand in the lab report below after conducting a group experiment in chemistry class. ![]()
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