Hydrochloric acid was then added to the solution until the bubbles stopped in order to completely get rid of all of the zinc. Next, we used vacuum filtration to filter the copper out of the solution. We drizzled alcohol and acetone over the copper to help it dry faster. Once it appeared dry, we weighed the copper and filter paper. When we subtracted the mass of the filter paper, the mass came out to 1.312g.
2. In order to eliminate any air trapped in the jet, the hydrochloric acid was allowed to run out and the burette was refilled to above the zero mark. 3. The tap of the burette was then opened to allow the acid to run out until the bottom of the meniscus was just on the zero mark when viewed at eye level. 4.
Investigating stoichiometry with Sodium Salts of Carbonic Acid Lab Report Experiment 7 Introduction: The purpose of this lab is to investigate and better understand chemical stoichiometry. In this experiment, you will be reacting sodium bicarbonate (NaHCO3) and sodium carbonate (Na2CO3) with hydrochloric acid (HCl) as shown below to produce sodium chloride, water and carbon dioxide. Using this chemical equation: NaHCO3 + HCl = NaCl + H20 + CO2. You will be given two unknown substances and expected to find which the sodium bicarbonate is and which the sodium carbonate is. You will do this by measuring the mass of the residue and comparing it to the thr=eoretical amount which is .165 g for Na2CO3 and .104 g for NaHO3.
To obtain the caffeine, the methylene chloride was removed from the extract, leaving us with our solid caffeine residue. Sublimation: We purified our solid caffeine through sublimation. By constructing a side-arm test tube apparatus, we vaporized and condensed the caffeine using a Bunsen burner. Upon cooling, the apparatus was carefully disassembled and the sublimed caffeine was scraped off of the test-tube collection surface and weighed. The melting point range was then determined by utilizing a melting point apparatus.
Then, by means of a dropper bottle and stirring rod, hydrochloric acid was added until all of the unknown carbonate appeared to have reacted. On a ring stand with a bunsen burner the HCl was evaporated, leaving only the NaCl. After cooling, the mass of the dish was taken once more. The mass of the left over NaCl was compared to the predicted yields to determine what the original carbonate was exactly. There was a high possibility for error in this experiment because the NaCl could not be heated a second time to make sure all of the HCl was evaporated.
The heat was not turned off until a change occurred in the reaction mixture. Distilled water was added into the reaction because it started to dry out. The beaker was then taken off of the hot plate to allow it to cool down. The solutions temperature dropped down to room temperature, which formed a clear liquid on top. In Cycle 4, the clear liquid formed in Cycle 3 was decanted.
Since the sodium chloride is soluble in water, gravity filtration will allow for separation of the calcium carbonate and sand (residue) from the NaCl+H2O (filtrate) solution. To separate the water from the NaCl, evaporation is utilized which leaves only the sodium chloride that was in the original mixture. When the NaCl has cooled to room temperature it can then be weighed. The residue from the gravity filtration (sand and calcium carbonate) is then added to 3M HCl to react with the calcium carbonate. Through decantation the resulting supernatant CaCl2+3M HCl solution can be separated from the sand that has settled at the bottom of the beaker.
5mL of acidified water will be measured, using a graduated cylinder, and will be transferred to the R tube, and will be immediately vigrously mixed with the reactants. Once the solution turns to an orange or red-brown color, a pipet will be used to quickly remove 30 drops of the solution, then transferred to the C tube, and the mixing will resume until the solution is close to room temperature. The solution will be filtered into the P tube, and the solution that is left in the R tube should be washed three times with 1mL of acidified water each time. The water should then be poured into the P tube, leaving the solid in the R tube. Using a test tube holder, heat the R tube over the Bunsen burner, moving the tube in a circular motion until all the water has evaporated.
By heating and mixing this solution, hydrogen gas was formed and vented through the vacuum filtration device. This mixture was then filtered twice in an attempt to purify the solution and remove residue from the break down of aluminum. After the solution had any impurities removed, it was cooled to room temperature and reacted with sulfuric acid and distilled water. During this step, it was important to add the acid slowly and avoid forming solids (this idea will be discussed later on). The insoluble solids were then filtered out using the same procedure previously mentioned.