Limiting Reactant Essay

In chemic receptions, the signifi go offce of chicaneing the alteration reactant is high. In order to increase the percent yield of product, increasing the constraining reactant, possibly, is the most effective. In this experiment we were capcap commensurate to calculate adjustment reactants from the reply of CaCl2. 2H2O + K2C2O4.H2O(aq). As a group, we obtained our season alloy of calcium chloride and potassium oxalate, and weighed the ad classification. We were able to make an aqueous solution from the mixing and distilled water. We drudgeed and strained off the solution, leaving the precipitate. Once the precipitate was dried-out overnight, it was weighed and the vision was measured. Then we calculated the moles of the precipitate. From these calculations, we established moles of the qualifying reactant, were the same tot up of moles in the product ground on the stoichiometrically balanced par. adjoining the percent yield of the limiting reactant was calculate d. In Part B of this experiment, devil solutions were added to the aqueous product in order to determine the limiting reactant. Once each solution was added, we were able to visibly see the precipitate forming when 0.5 M CaCl2 was added. This made us conclude the limiting reactant was in fact CaCl2. IntroductionStoichiometry is a section of chemistry that involves using relationships between reactants and/or products in a chemical substance reaction to determine desired quantitative data. Doing stoichiometry can calculate masses, moles, and percents with a chemical equation. The use of stoichiometry is how we were able to find the limiting reagent in this lab. We know that the limiting reagent is the chemical that will be used up first. Two factors affect the yield of product in a chemical reaction the amounts of starting materials and the percent yield of the reaction. Under certain conditions such as temperature and pressure, can be correct to increase the yield of a desired pr oduct in a chemical reaction entirely because the chemicals react according to fixed mole ratios, only a limited amount of product can form from measured amounts of starting materials. A way for us to better understand this concept of the limiting reactant is to observe the reaction in our experiment. The reaction of calcium chloride dehydrate, CaCl22H2O,and potassium oxalate monohydrate, K2C2O4H2O, in an aqueous solution.For the reaction ashes in this experiment, both the calcium chloride and potassium oxalate are soluble sodium chlorides, but the calcium oxalate is insoluble. The ionic equation for the reaction is Ca2+(aq)+2Cl-(aq)+2K+(aq)+C2O42-(aq)+3H2O(l)CaC2O4H2O(s)+2Cl-(aq)+2K+(aq)+2H2O(l) presenting only the ions that show evidence of a chemical reaction, formation of a precipitate, and by removing the mantrap ions, no kind of ionic form during the reaction, we have the net ionic equation for the observed reaction is Ca2+(aq)+ C2O42-(aq)+H2O(l)CaC2O4H2O(s). In Part A of this experiment the solid reactant brininesss CaCl2H2O forms and K2C2O4H2O form heterogeneous mixture of unknown composition. The mass of the solid mixture is measured and then added to water-insoluble CaC2O4H2O forms. The CaC2O4H2O precipitate is tranquil by gravity filtration and dried, and its mass is measured. In Part B, the limiting reactant for the formation of solid calcium oxalate monohydrate is decided from cardinal precipitation test of the final reactant mixture from Part A. The first test we tested the mixture for an excess of calcium ion with an oxalate reagent and the second test the mixture is tested again for an excess of oxalate ion with calcium reagents. Materials and MethodsMaterials laboratory coatSafety goggles1 250ml beaker1 piece of filter coverfunnel1-2 grams of salt mixtureA hot plateA weighing casingMethods1. Experimenters obtained one 250 ml beaker and weighed it on the weighing scale and recorded the results2. The 250 ml beaker was then filled with 1-2 grams of the salt mixture and weighed again3. speed of light ml of distilled water was added to the salt mixture4. The beaker was situated on the hot plate and brought to a boil then removed5. After cooling, the experimenters filtered the mixture using the filter paper and funnel6. Experimenters left the filter paper to air dry overnight7.The air dried filter paper was then placed on the weighing scale and results were recorded ResultsIn experiment A the results from the precipitation of CaC2O4 H2O from the salt mixture were obtained by weighing the items listed on Table 1 on a scale. Table 1. aggregative of Beaker (g)102.994g plenty of Beaker and Salt Mixture104.683gMass of Salt Mixture (g)1.689gMass of Filter Paper (g)1.336gMass of Filter Paper and CaC2O4 H2O (g)2.000gMass of Air-Dried CaC2O4 H2O (g)0.664gIn Experiment B the limiting reactant was determined to be CaCl2 when two drops of the test reagent 0.5 M CaCl2 was added to the supernatant liquid in test subway system 1 , and a precipitate formed. Since there was a reaction, there was C2O42- in excess and Ca2+ is the limiting reactant in the headmaster salt mixture present in test tube 1 . This was further confirmed when two drops of the test reagent .05M K2C2O4 was added to the supernatant liquid in test tube 2. There was no precipitate because Ca2+ was non present since it was the limiting reactant and instead C2O42- was in excess. Table 2.Moles of CaC2O4 H2O precipitated (mol).0045 (mol)Moles of limiting reactant in salt mixture (g)CaCl2 .0004 (mol)Mass of limiting reactant in salt mixture (g)CaCl2 .4995 (grams)Mass of excess reactant in salt mixture (g)Ca2C2O4 1.113 (grams)Percent limiting reactant in salt mixture (%) CaCl34% (34.1%)Percent excess reactant in salt mixture (%) K2C2O466% (65.8%)DiscussionThe data of the mass of the salt mixture was a big blusher for finding the moles of CaC2O4 precipitated. The molar mass of CaC2O4 H2O was 146.097 grams. The mass of the air-dried CaC2O4 H2O Ca Cl2, was .664g as recorded in table 1. Using a calculation of .664 x 1 mole / 146.097 a result of .0045 mol was recorded in table 2. The test done in Experiment B allowed us to know without any calculations that Ca2+ is the limiting reactant. This allowed us to conclude that the moles of the limiting reactant were .0004 (mol) of CaCl2. In order to achieve the grams of the limiting reactant, the moles of the limiting reactant must be multiplied by the molar mass of the limiting reactant.Therefore the mass of the limiting reactant was .0045 moles and multiplied by its molar mass of 111g to result in .4995g of the limiting reactant in the salt mixture. Next the mass of the excess reactant in the salt mixture was calculated using the same method as the limiting reactant except the molar mass of the excess reactant was used to result in 1.113 (grams) Ca2C2O4 . The final ill-use in the process was to find the percent by mass of the limiting reactant. Since Experiment B allowed us to dete rmine that Ca2+ is the limiting reactant, therefore to find the percentage composition it is necessary to divide the limiting reactant mass by the mass of the original sample then multiply by 100. This provided a result of 34%, and to find the excess percentage, this value was subtracted from 100 to yield 66% of K2C2O4 as the percent of excess reactant in salt mixture. Error AnalysisPossible errors efficacy be attributed to careless errors in reading the scale to measure the mass of the beaker, salt mixture or filter paper. Even when befitting care is taken in reading the instruments, systematic errors can present themselves in the instrument used to measure mass. Here, a calibrated scale was used to measure mass, and the systematic error is unknown since it is one of the hardest errors to detect. These two sources of errors might help explain the .1% missing from the CaCl2 and K2C2O4 salt mixture recorded in Table 2.Precision and truthWhile accuracy deals with how close a measur ed value is to a true or current one, precision deals with how reproducible a given measurement is. Here the mass of the beaker, salt mixture, and filter paper are all precise because they are easily reproducible since it simply involves putting the items on a scale. If the process was repeated 50 times the results would not vary or at the least by .0001 grams based on some outside factor. The mass of the air-dried CaC2O4 H2O is accurate because it was calculated as true by subtracting the mass of the filter paper from the mass of the filter paper and the CaC2O4 H2O. ConclusionAs we have stated previously, CaCl2 was our limiting reactant based on the precipitates observed. We were able to rule out Ca2C2O4 because of the lack change in our precipitate..It was important to note that a limiting reactant in a chemical reaction limits the amount of product that can be formed. The reaction will stop when all of the limiting reactant is consumed. The excess is the reactant in a chemical r eaction that remains but there is nothing with which it can react. Taking this cognition we have gained in appropriately observing the results, we can apply it to future experiments in chemistry in order to evaluate how much product one might want to produce in a given chemical reaction.Reviewing other experiments, from other schools, it is apparent that the need for appropriate data collection in this type of experiment, will help in identifying the excess and limiting reagents. As was the case in UCCSs Chem 103 Lab Manual, following the procedures and doing them in the proper order are vital to ensuring success in proper reactions.ReferencesTro, Nivaldo. Chemistry A Molecular Approach. 3rd ed. Boston, MA Pearson Education, Inc.Beran, J. A. Laboratory Manual for Principles of General Chemistry. 8th ed. Hoboken, NJ John Wiley & Sons, Inc. 2009 Beran, J. A. Laboratory Manual for Principles of General Chemistry. 9th ed. Hoboken, NJ John Wiley 2010 UC Davis ChemWiki. Stoichiometry and Balancing Reactions. http//chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Stoichiometry_and_Balancing_Reactions UCCS Chem 103 Laboratory Manual. Experiment 3 Limiting Reactants. http//www.uccs.edu/Documents/chemistry/nsf/103%20Expt3V-LR.pdf Masterson, W, Hurley, C. Chemistry Principles and Reactions. 6th ed. Belmont, CA Brooks/Cole Cengage Learning 2009.