Baking Soda and Vinegar (Limiting Reactants) Lab



Baking Soda and Vinegar (Stoichiometry) LabTheory In class, we’ve learned to compute how much of a chemical product that can be made when we mix measured amounts of reactants. In this lab, you will be actually using this information to predict how much product will be made. We will then use your theoretical value and compare it to the actual value to determine your percent yield.The reaction you will be working with should be familiar to you from the elementary science fair volcanoes: You will be mixing baking soda (NaHCO3) with vinegar (CH3COOH) to generate carbon dioxide (bubbles), water, and sodium acetate (NaC2H3O2) which is a food preservative.Purpose To calculate the percent yield of sodium acetate using stoichiometry.SafetyPlease wear safety goggles at all times, be careful of loose clothing or long hair, and do not touch the Erlenmeyer flask with your bare hands after it has been heated (use a hot pad or proper transfer device). ProcedureSection 1: Computing the mass of the limiting reactant (baking soda) In this lab, you will react baking soda with an excess of vinegar. For thisreaction, you need to use 0.025 moles of baking soda. In the space below,calculate the mass of baking soda (sodium hydrogen carbonate) needed:Section 2: The reactionMeasure out the mass of baking soda needed. Make sure to obtain this exact amount as close as you can. Record the exact amount obtained.Obtain and record the mass of a completely-dried 500 mL Erlenmeyer flask (or similar size).Then, add your baking soda to the 500 E. flask.Obtain approximately 75 mL of vinegar in a beaker.Add a small portion of the vinegar to the E. flask containing the baking soda. Swirl the mixture together. Continue to add small amounts of vinegar to swirl until you no longer observe bubbles. When no more bubbles are observed, use a stirring rod to stir the mixture for two minutes. This ensures that all of the baking soda is dissolved.Set the hot plate to its lowest setting and place the flask on the plate. Using crucible tongs, occasional remove and swirl the flask. You are doing this to MAKE CERTAIN THE SODIUM ACETATE IS NOT BURNING. This is VERY important!Once all of the water has been evaporated, turn off the hot plate and allow the E. flask to cool. This should take approximately five minutes.Once the E. flask is cooled enough, use the scale to mass your E. flask with sodium acetate. Record the mass.Rinse your flask with water and dump the contents down the drain. CalculationsWrite and balance the equation of the reaction that we did in lab (see board or ask if in doubt (it’s not a “traditional” double replacement).Calculate the actual yield (mass) of sodium acetate. Actual yield is ACTUALLY how much of our goal product we obtained!Calculate the theoretical yield (mass) of sodium acetate. Theoretical yield is how much we should have gotten in THEORY! You’ll need to do a limiting reagent problem to calculate this.Calculate the percent yield of sodium acetate recovered in lab. Percent yield is the PERCENT of the goal product we got based on what we should have gotten! For example… if theoretical yield is 10g and actual yield is only 5g, our PERCENT yield is 5/10 x 100 (or 50%). If Yt is 10g and Ya is 15g, our Y% is 15/10 x 100 (or 150%).Practice problem: If we mix 50 grams of sodium phosphate with an unlimited amount of iron (III) oxide, what is the percent yield of sodium oxide if you obtain 27.4 grams of sodium oxide in lab? QuestionsWhat is the importance of this process you just went through?How did you know that a chemical reaction was taking place when you combined the baking soda and vinegar? Why did you use an E. flask to combine the baking soda and vinegar?Why did you heat the sodium acetate?Why did you have to extra care in not burning the sodium acetate?Why is it important to cool a container before measuring its mass (don’t talk about the safety issue of burning your fingers)? ................
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