Stoichiometric relationship between the quantities of substances in a chemical reaction.

Have a little read: ... Eirik Hjertenæs Experiment 7 Stoichiometric relationship between the quantities of substances in a chemical reaction Introduction: Stoichiometry is concerned with the quantitative relationship between the amounts of substances involved in chemical reactions. In this experiment we were to collect quantitative data in the reaction between Potassium iodide and Lead (II) nitrate. This reaction produces a bright yellow precipitate of lead (II) iodide, PbI2. This experiment was originally designed to be preformed with sodium iodide instead of potassium iodide. The experiment was meant to be a class activity and the class was divided into groups which were to do the reaction with the same amount of Pb(NO3)2 but different amounts of NaI. The amount of NaI for each group was given in the description but since we used KI instead we had to calculate new masses so that the amount of iodide would be the same. By measuring the weight of the reagents and the yield we should be able to say something about which substance is the limiting reagent in the different cases. I predict that our data will correspond to the balanced equation of the reaction which is: Pb(NO3)2 + 2 KI ---> PbI2 + 2 K + 2 NO3 Equipment: * 1,66 g sample of Pb(NO3)2 * sample of KI (in our group 1,16 g) * Filter funnel * Filter Stand * Filter paper * Glass rod * "Policeman" * Balance * Distilled water Procedure: 1. The first thing we did was to calculate how much KI we needed and weighed the correct amount. 2. Then we added 35 ml of distilled water to the KI and the Pb(NO3)2 and stirred with a glass rod to help it dissolute. 3. The next thing we did was to add the Pb(NO3)2-solution into the KI and rinsed the empty beaker three times with about ml of water to make sure we got all of the Pb(NO3)2 over. 4. We stirred the mixture and let it stand for 5-10 minutes and left the glass rod in the beaker. 5. We weighed a filter paper and wrote down its mass. 6. Then we folded the filter paper and placed it in a filter funnel in a filter stand. We moist the paper so it would stick to the filter funnel. 7. We carefully filtered the solution containing the precipitate, and ensured a quantitative transfer to the filter paper. We used a glass rod to direct the precipitate into the paper like in figure 7.1. Fig7.1 8. Then we rinsed the beaker to ensure all of the precipitate had