Limiting Reactants

Limiting Reactants Introduction Summary: In this lab, we constructed an explored experiments based on the concept of limiting reactants building off from the conservation of mass lab. We observed a precipitate form between the two chemicals: silver nitrate and sodium chloride. We then discussed limiting and excess reagents using food analogies, and applied those to designing our own experiment to find the excess reagent between silver nitrate and sodium chloride. It is important to know the limiting reactant, because this is what stops the reaction and limits the product from further being produced. [1] Procedure Phase 1: Making observations, downloaded from ICN Prediction: We predict that one of the reactions is going to be excess and one of the reactants is going to be limiting 1. Record solution pair (A&B or 1&2) 2. Measure 10.0 mL of each of your assigned solutions in a graduated cylinder. 3. Record the exact volumes you used in your notebook. 4. Now, mix the two solutions in a labeled beaker 5. Allow the mixture to sit for 15 minutes for the reaction to complete. During this time, you should move on to phase 2 in the breakout room . [1] Phase 2: Exploring the analogy, downloaded from ICN on 10/16/16 1. The first person in the group should reads the passage out loud 2. After listening, partner 1 should ask partner 2 to answer the questions, while explaining their thinking process out loud. 3. Partner 2 reads the next passage out loud to partner 1. 4. Partner 2 should then ask partner 1 to answer the questions while explaining their thinking out loud. [1] Phase 3: Designing experiments, downloaded from ICN on 10/16/16 1. Obtain solution from phase 1. 2. Filter out mixture from phase 1 by using filter paper, into a new beaker. 3. Let mixture filter through. 4. Obtain 2 beakers, one containing Ag(NO 3 ) and the other containing NaCl. 5. Pour leftover mixture from phase 1 into both beakers. 6. Record which chemical reacted, that chemical will be the excess. Data: Phase 1 1&2 Observations: [1] - We couldn’t figure out which solution was more concentrated visually - The precipitate that formed looked different than last weeks, it was a lot cloudier and milkier. Phase 2 Phase 3 Results: Ag(NO 3 was the excess (reacted solution) - The beaker on the left NaCl was the limiting (unreacted solution) - The beaker on the right Analysis: For phase 1, we observed a precipitate form between solutions 1 and 2, and we used this precipitate in phase 3. For phase 3, we based our experiment off from the phase 2 analogy; we discussed that the limiting reactant would be the solution that has nothing leftover, and the excess reagent would be the solution that was leftover. Based on this information, and relating to last week’s experiment, we filtered out the limiting reactant (the precipitate) and tested the leftover solution in a beaker with NaCl and a beaker with Ag(NO 3 )Whichever chemical reacted to the leftover solution from phase 1 was found to be the excess reagent, and the chemical that was filtered out was found to be the limiting reactant. Claim: We claim that our data shows that Ag(NO3) is the excess reagent. In phase 1, a precipitate formed between the two chemicals 1 and 2, we used this precipitate to figure out which was the excess and which was the limiting by filtration. Ag(NO 3 )was found to be the excess reagent because it reacted to the leftover solution; whereas, NaCl did not react to the leftover solution.