Leggi di Lavoisier e di Proust - in inglese - Popolis

More documents

Recommendations

Info

4) Brief theoretical premiseThe Lavoisier’s law affirms that, during a chemical reaction, the mass does not change.m reagent= m products: “nothing is created, nothing is destroied, but only transformed.”The Proust’s law states that, when two elements react to form a compound they do it according toa defined ratio of masses.5) Description of the stages doing the experience1. Phase: to reset the balance (optional);2. Phase: to put the empty small glass container on the digital electronic balance A) and to reset it;3. Phase: to value the mass of the iron (1g) on the balance setting it into the small glass containerB)4. Phase to repeat the phase 2 with the other small glass container A).5. Phase to value the mass of the sulphur (0,57g) C) putting it into the other small glass containerplaced on the balance;6. Phase: to weigh the empty test tube D);7. Phase: to put the iron and the sulphur into the test tube using the funnel and with a thin glassstick to mix the mixture in order to make it more homogeneous, E);8. Phase: to heat the test tube containing the mixture on the gas stove for about five minutes F);9. Phase: to wait until the chemical reaction occours; later, when the test tube is cooled, take itaway from the gas stove and set it on the balance;10. Phase: to value with the balance the mass of the test-tube containing the ferrous sulphide (FeS)G;)11. Phase: to check if the Lavoisier’ law and the Proust’s law and have been proved;12. Phase: to prove that the test tube with the FeS is attracted by the magnet H) and to break thetest tube with a weight in order to observe the product of the reaction;13. Phase: to gather the data in a table;14. Phase: to calculate the percentage error comparing the mass of the reagent with that on of theproduct.6) Physical quantities measuredQuantity Symbol Units Instrumentmass m (g) Digital electronic Balance7) Characteristics of the instruments used for the data loggingInstrumentResolution CapacityDigital electronic Balance 0,01(g) 1000(g)8) Gathered dataMFe=y1(g) MS=y2(g) M empty test M test tube E%(M)tube=y3 (g) +FeS(g)= y41,00 0,57 15,92 17,49 0
9) Mathematical formulas used for the work out of the gathered datareagentproductFe A=56 1 mol of Fe=56(g)Eac(M)= y4-(y1+y2+y3)S A=32 1 mol of S=32(g)Erc(M)= Eac(M)/y456/56 (g)Fe+32/56 (g)S=1,57(g) E%c(M)= Erc(M)*1001,00(g)Fe + 0,57(g)S =1,57(g)m=15,92(g) Fe+S m=17,49(g) Fe+S +∆Q m=17,49(g)before the reactionafter the reaction10) Final conclusionAnalysis of the experiment and data interpretation- The E%(M) is null and the reaction had entirely occurred.- at the end of the reaction, the mass of the reagents was equal to the mass of the products so thatthe Lavoisier’s law had been confirmed..- breaken the test tube with a weight, the magnet attracted the whole compoud and not only theiron has it happend before the chemical reaction had course. This fact confirms that a newcompound was formed.- We realize also that the Proust’s law had been confirmed; the ratio of combination of theelements had been R=1/0,57Causes of the errorWe did not have any error concerning the mass, but if we should have any it should be due to thefollowing reason: mass loss because part of it (expecially regarding the sulphur) may remain stickedto the glass container; moving of the air during the weighting with the balance; evaporation of thesulphur during the chemical reaction.AdviceFor a better conduction of the experiment in order to get less percentage error (concerning the mass)in the final result, it is advisable to make the mixture the most homogeneous as possible; to lead theexperiment in a place sheltered by the air; before removing the test-tube, to put the residues ofsubstances attached to the small glasses containers into the test tube itself; to wait until the reactionis completed before removing the test-tube from the gas stove.Difficulties to cope with doing this experimentNone.Time required to do the experimentAbout 30 minutes.
Page 1: Date: 05/21/08 Student: Comincini L

Leggi di Lavoisier e di Proust - in inglese - Popolis

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?