Law of Constant Composition Lab Essay

Purpose To determine the fate milligram by quid in milligram oxide and to observe if the theatrical role write up is unremitting by comparing set results. speculation/Prediction The percent writing by mass of milligram in corpuscleic number 12 oxide will not change importantly with each base that conducted the experiment. The news report of each pump should stay the same and just ab off(prenominal) differences moldiness be due to al nigh actus reus.MaterialsMagnesium scavengeCrucibleCrucible retainClay triangleIron ringRetort standTongsBalancebunsen burninger burnerProcedure1.obtained a strip of atomic number 12 between 30-40 cm long2.coiled atomic number 12 strip into a tight roll3. metric the mass of the melting pot and cover4.Added the atomic number 12 strip to the melting pot and measured the milligram, crucible and cover together.5.Partially covered the crucible with the cover and heated it using a Bunsen burner until the atomic number 12 ignited.6.Tur ned clear up Bunsen burner.7.waited for combustion to proceed8.when the reaction appeared completed, heated the crucible again for another five minutes9.allowed crucible to cool for ten minutes10.measured the mass of the crucible, cover and magnesium oxideObservationsWhen ignited, the magnesium strip gave off a bright light.There was a colour change on the magnesium.It started out as silver and turned into a white colour.The combustion gave off a distinct odour.The end result was a white powder but just about magnesium had been left in its passkey shape.According to the theory of J.L. Proust, a mix always has the same per centum organisation no matter how it is prepared. For all ternary of our own individual groups trials, we obtained the same function composition and this satisfies Prousts theory.This is as well accurate with what we devote read in the textbook alchemy 11 on the Law of expressed Proportions on pages 147 150.2.What conclusion can you constrain upon the trend results?The conclusions I can consider based upon the class results are that the composition of a compound must shift because everyone had a antithetical answer. In most cases, the percent composition of magnesium in the compound was very different from what my group achieved. However, sometimes, the classes results were quite an similar to my own.The theory that C.M. Berthollet introduced slightly the composition of a compound was that a compound has an infinite number of compositions depending on the proportions of the components that were utilise in its preparation. His theory satisfies the results obtained from the all told class. Since every group had a different amount of magnesium they must also bear had a different composition of magnesium in the compound wee-weeed, magnesium oxide.However, this is inconsistent with what we bugger off been taught and with what is written in the textbook. Since the textbook is a more authoritative source of in pee-peeation, I must give over that the moderateness for this difference in results whitethorn be attributed to error on the transgress of the savants conducting the experiment.3.Which French Scientist would you tend to hold in? Explain.The French scientist that I support is J.L. Proust. I halt with Prousts theory because I moot that if the composition of a substance were to change, so would its properties. An frank example of this is one aread in the textbook water and hydrogen peroxide. The saucer-eyed addition of a hydrogen atom to the compound of water can devote a liquid that is essential to aliveness become deadly. Since I know that the percent composition of a particular substance is the same no matter where, how or when it is made, I must agree with J.L Proust and support his theory.Sources of ErrorOne reason why a student may have obtained a higher(prenominal) portion of magnesium than the quiet of the class is during the experiment, mass must have been lost. This could h ave been done in umpteen ways. Often, the magnesium took too long to ignite and students began to put together it straight into the flame to ignite it and whence put it back into the crucible. Sometimes, the magnesium limp and little pieces of it broke off. In addition, the magnesium would sometimes ignite and then stub out itself. In the constant removal of the magnesium from the crucible, mass was lost in the form of ashes. When mass is lost during the experiment, the total mass of the compound is press down and when the mass of magnesium was divided by the total mass, yielded a higher percent of magnesium.One reason why a student may have obtained a lower percentage of magnesium than the rest of the class is the magnesium did not properly combust. In many cases, the magnesium would extinguish itself and would not burn completely. This resulted in some white powder, ash, and some magnesium still in the same shape that it was when we began the experiment. This suggests that it did not burn with the rest of the magnesium ribbon and therefore, did not form the compound with oxygen. This would yield in a higher total mass than what it should have been and when the mass of magnesium is divided by the total mass, would give a lower percentage.The following calculation shows the actual percentage of Magnesium in the compound magnesium oxide.Molar mass of MgO = 24.3 + 16.0= 40.3For 1.00 mol of MgO%Mg = 24.3 / 40.3 x100= 60.3%Therefore, the actual percentage value of Mg in MgO is 60%The following calculation shows the percentage error for my own groups result% error = (experimental evaluate) / accepted x 100= (72 60) / 60 x 100= 20%Therefore the percentage error for my group was 20%.ConclusionBased on the data collected by each group, the composition of a substance must change depending on the proportions of the components that were used in its preparation.However, as explained earlier, the textbook and the properties of matter state otherwise. Scientifically, if the composition of a compound was to change, so would its properties. The results obtained by the class are quite the opposite of what has already been proven by Proust to be true and therefore, I believe that the evidence obtained by our chemistry class is the result of many mistakes and cannot be used to convey the idea of the Law of ageless Composition which states that the composition of a limited compound is constant.