Predicting the Products of Double Replacement Reactions Essay

Introduction – A double replacement reaction is a chemical reaction between two compounds where the positive ion of one compound is exchanged with the positive ion of another compound. If you have the reactants of two reaction solution that you can determine the products. All you need to do is pair the positive parts of the compounds with the other compounds negative part. Once you find the products you can determine their phase of matter by using Table H. You can also use Table F to determine the solubility guidelines for aqueous solutions. If the product falls under soluble or exceptions to insoluble it is in the aqueous stare. If the product falls under insoluble or exception to soluble it is a precipitate. Once you have completed those steps you can determine if a equation went to completion or not. In order for a reaction to go to completion it must have one of the following three things. First, a gas is produced. This gas is usually H2, O2, or CO2. Secondly, a covalent compound (such as water) is formed. Finally, a precipitate (solid) is formed. When none of those things happen it is considered to be â€Å"no reaction.† When one of those things does happen the reaction is considered to be â€Å"completed.† It is considered to be completed because all of the reagents in the sample have completely reacted out. Purpose – The purpose of this lab was to be able to predict the phase of matter after a double replacement reaction, what the products were, and if the reaction was completed or not. Materials and Methods – †¢.1 M NaCl †¢.1 M AgNO3 †¢.1 M Na3PO4 †¢.1 M NaOH †¢.1 CuSO4 †¢Five droppers †¢Spot Plate †¢Pen/Pencil †¢Paper †¢Goggles †¢Apron Safety Precautions – †¢Wear goggles and apron at all time while inside the lab. †¢You may use rubber gloves o protect your hands from the chemicals that will be used in the lab. †¢If any chemical gets on your skin tell the teacher right a way and thoroughly rinse it with water. †¢If any chemicals happen to get into your eye use the eye wash bottle or the emergency eye wash station. †¢Make sure you wear closed shoes in the lab. †¢No horse playing or inappropriate behavior in the lab. †¢When the lab is complete dispose of the chemicals correctly and place them correctly on the drying rack. Procedure – First, using a spot plate, place five drops of NaCl solution into wells I and IV, five drops of NaOH into wells II and V, and five drops of Na3PO4 into wells III and VI. Next, using the diagrams listed on the lab sheet, add five drops of CuSO4 to wells I, II, and III and five drops of AgNO3 to wells IV, V, and VI. Finally, note any color changes or precipitates formed and record your observations. Observations and Data – I. Appearance before: Clear liquid state. After: Still liquid state, light blue color. II. Appearance before: Clear liquid state. After: Changed to solid state, dark blue. III. Appearance before: Clear/transparent liquid state. After: Solid state, light blue. IV. Appearance before: Clear liquid state. After: White, cloudy, solid state. V. Appearance before: Clear liquid state. After: Cloudy, bits of pieces, brownish, solid state. VI. Appearance before: Clear and bubbly. After: Yellow, cloudy, precipitate present, solid state. Question – 1.Soluble means a substance is able to be dissolved, esp. in water. 2.Insoluble means a substance is incapable of being dissolved. 3.When the symbol (aq) is placed next to an ionic compound it means any solution in which water (H2O) is the solvent. 4.A precipitate is to form an insoluble compound either by reacting two salts or by changing the temperature to affect the solubility of the compound. Also it is the name given to the solid that is formed as a result of a precipitation reaction. 5.You can identify a precipitate when it is written in a reaction if there is a (s) next to one of the reactants or products. If that (s) symbolizing a solid is not present you will have to look at Table F. Table F shows ions that form soluble/insoluble compounds. If the product/reactant falls under insoluble or the soluble exception column it is a precipitate. You can identify a precipitate in a reaction if the reactant or product is in solid form. 6. Balanced equation and state: a.No Reaction b.NaOH + CuSO4 –> Na2SO4 + Cu(OH)2 (s) c.2Na3PO4 + 3CuSO4 –> 3Na2SO4 + Cu3(PO4)2 (s) d.NaCl + AgNO3 –> NaNO3 + AgCl (s) e.NaOH + AgNO3 –> NaNO3 + AgOH (s) f.Na3PO4 + AgNO3 –> NaNO3 + Ag3PO4 (s) Conclusion – The main idea of this experiment is that if you have the reactants of a double replacement reaction that you should be able to find out several things. First, you can figure out the products from switching the positive ion with the other positive ion. Once you have found the products you can determine the phase of matter they are in from Table F and H. Finally, you can also determine whether the reaction went to completion or not. The observations and data above leads me to believe that our experiment is valid. We were very careful and observant of the directions that needed to be taken. Once source of error could have been that certain substances were placed in the wrong wells, causing your data to stray from the correct information. One way this experiment could be applied to a real life situation is he residue in the bottom of a glass in your bathroom. There is stuff dissolved in water, and any trace of water left in a glass will eventually evaporate and leave the residue. Another example can be found if you have ever been to a salt marsh along the ocean, you will see lots of salt deposits, which are just precipitated salt from the ocean water. One improvement that can be done to the lab so that students obtain more valid information is having bigger wells. This way students can see which solutions they are mixing and observe the reaction better. From learning it in class on the smart board to actually seeing the reaction using chemicals, this lab has really helped me further understand how double replacement reactions work, and what can be learned when all you have are the products.