The Stoichiometry of a Reaction

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Experiment 5 The Stoichiometry of A Reaction Group Member(s): Introduction: This experiment provides a method to determine the mole ratio in which two substances combine chemically. Such information is helpful in determining the stoichiometry of a reaction, i.e. the balanced chemical equation and the information that can be derived from it. The principle underlying this experiment is based on keeping the quantity of one reactant constant while varying the quantity of a second reactant. The mass of the precipitate produced is then used as an indicator of the effect of varying the quantity of the second reactant. When enough of the second reactant has been added to completely react with the first reactant, there will be no further increase in the amount of the precipitate produced, regardless of how much of the second one is added. Apparatus and Chemicals: 0.1 M K2CrO4 0.1 m Pb(NO3)2 Burets 150-mL beaker 5% nitric acid hot plate stirring rod filter paper Wash bottle funnel Procedures: * 12.00 mL of 0.100M K2CrO4 solution is dispensed into a clean, dry, small beaker. * 11.50 (the assigned volume) of 0.100M Pb(NO3)2 solution is dispensed from a second buret into a second clean, dry, small beaker. * 12.00 mL of the K2CRO4 solution was slowly poured into the beaker containing the Pb(NO3)2Vsolution while stirring the Pb(NO3)2 solution. * The K2CrO4 beaker is rinsed with 10 mL of 5% nitric acid solution and added into the beaker. * The beaker is heated on a hot plate in the hood for 2-3 min. * Our professor demonstrated the correct filtration technique. * The mass of a piece of filter paper is determined to the nearest milligram. * The filter paper is than folded and inserted into a funnel and moist with distill water. * The top of the filter paper is pressed to the funnel such that a slight suction is created.
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