Decomposition of Sodium Hydrogen Carbonate , Lab Reports of Chemical Experimentation

Download Decomposition of Sodium Hydrogen Carbonate and more Lab Reports Chemical Experimentation in PDF only on Docsity! Decomposition of Sodium Hydrogen Carbonate Goal: To experimentally determine decomposition reaction of sodium hydrogen carbonate on reaction stoichiometry. Introduction Stoichiometry is the study of mass relationships in chemistry. In this lab, you will decompose baking soda (sodium hydrogen carbonate or sodium bicarbonate) and use the mass relationships to determine how baking soda decomposes. Baking soda is commonly used in baking to provide a “rise” to baked goods. When baking soda decomposes it produces a gas (carbon dioxide) which is trapped in pockets and giving the baked goods an airy texture. Sodium bicarbonate may be more familiar to you as baking soda. There are three theoretically possible chemical reactions that could occur during the thermal decomposition of baking soda. 1) sodium bicarbonate (s) → sodium hydroxide (s) + carbon dioxide (g) 2) sodium bicarbonate (s) → sodium oxide (s) + carbon dioxide (g) + water (g) 3) sodium bicarbonate (s)→ sodium carbonate (s) + carbon dioxide (g) + water (g) By comparing the theoretical yields of the possible solid products with the actual experimental yield of the product, you will be able to determine which of the above decomposition reactions occurred. In this experiment, you will determine the products from the thermal decomposition of sodium bicarbonate. The experiment is straightforward. A sample of sodium bicarbonate is weighed and heated. The final product will be weighed and the mass of product will be compared to the theoretical yield of the three possible products to determine how sodium bicarbonate decomposes, and whether its decomposition gives different products when heated to a low temperature versus a high temperature. Laboratory Activity Equipment hot plate analytical top-loader balance clean dry beaker Beaker tongs Chemicals NaHCO3(s) Safety Hazards – Caution – hot plates are hot! Even when they may not look hot. When determining if a beaker is still hot, slowly bring the back of your fingers towards it. If you sense any heat radiating from the beaker, do not touch, wait! PROCEDURE 1) (Run 1) Weigh a clean dry small beaker record the weight. 2) Add between 4 and 5 grams of sodium bicarbonate and reweigh. Record the weight. 3) Set the hot plate at 200 degrees C. Set the beaker on the hot plate and heat for 15 minutes. 4) Take the beaker off the hot plate and let cool until it reaches room temperature. reweigh. 5) (Run 2) Get a new clean dry beaker, weigh, add 4 to 5 grams of sodium bicarbonate and reweigh. Record all the weights. 6) Set the hot plate to 400 degrees C. Put the beaker on the hot plate and heat for 15 minutes. 7) Remove the beaker from the hot plate and allow it to cool to room temperature and reweigh. 8) Dispose of waste in the sink. 2) Using the mass of sodium bicarbonate used for runs 1 and 2, calculate the theoretical yield of solid products from each of the possible decomposition reactions, then calculate the percent yield by dividing your actual yield by the theoretical yield you calculate for each reaction. Percent yield = | 𝑎𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 | x 100 Reaction A ___NaHCO3(s) → ___NaOH(s) + ___CO2(g) Run 1: Initial grams of NaHCO3 = __________________ Theoretical yield (grams) of NaOH:___________ Percent yield (Run 1) = ____________________ Run 2: Initial grams of NaHCO3 = __________________ Theoretical yield (grams) of NaOH:___________ Percent yield (Run 2) = ____________________ Reaction B ___NaHCO3(s) → ___Na2O(s) + ___CO2(g) + ___H2O(g) Run 1: Initial grams of NaHCO3 = __________________ Theoretical yield (grams) of Na2O:___________ Percent yield (Run 1) = ____________________ Run 2: Initial grams of NaHCO3 = __________________ Theoretical yield (grams) of Na2O:___________ Percent yield (Run 2) = ____________________ Reaction C ___NaHCO3(s) → ___Na2CO3(s) + ___CO2(g) + ___H2O(g) Run 1: Initial grams of NaHCO3 = __________________ Theoretical yield (grams) of Na2CO3:__________ Percent yield (Run 1) = ____________________ Run 2: Initial grams of NaHCO3 = __________________ Theoretical yield (grams) of Na2CO3:__________ Percent yield (Run 2) = ____________________ 3) For Run 1, which reaction was closest to 100% yield? For Run 2, which reaction was closest to 100% yield? 4) During Run 1 (heated to 200°C), do you think that the sodium bicarbonate turned into NaOH, Na2O, or Na2CO3? What about during Run 2 (heated to 400°C)? Did they form the same product, or different products? Was this expected or unexpected? Explain briefly.