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.
Experimental Procedure: Place .15 g of each of the unknown solutions into the 250 mL beaker and dissolve both in 50 mL of distilled water. Add 5-6 drops of bromocresol indicator to each beaker. The solution should turn blue. Put HCl in a burette and place the beaker underneath, slowly begin to drop the HCl into the first beaker until it turns green. If it turns yellow it is overtitrated and the experiment will have to be restarted. Then place the beaker on a burner and heat to evaporate all of the CO2, when the solution is a blue color take it off and let cool. Titrate the solution again with the HCL, this time the solution should turn yellow. Place the solution on the burner again and wait until all of the H2O has evaporated leaving only NaCl residue. Weigh the beaker with the residue. Clean out the beaker and weigh the beaker alone. Subtract these from one another and this will give you the weight of the residue left. The one that weighs less is NaHCO3 and the one that weighs more is Na2CO3
Results (20 points)
(1) Presents table(s) and calculations clearly and accurately. All data (grams of unknown
samples, mL HCl, theoretical and actual yield of NaCl, etc..) are included. No hand drawn
figures/tables are accepted.
(2) Contents statements for...