Enthalpy Lab

LAB OF ENTHALPY CHANGE IN blaze Objective Determine the Enthalpy channelize of combustion ? Hc of three different inebriants. M ethyl alcohol, ethyl alcohol and Isopropilic acid. Procedure 1. postulate the spirit micro burninger with Ethanol and weight it 2. Pour degree Celsius cm3 of body of water into the aluminum cup 3. rank the cup a short distance over the micro burner 4. pass judgment the temperature of water 5. When the temperature of the water has go by 10C, record the temperature. 6. Reweight the microburner. Record 7. Repeat steps 1 to 6 but forthwith with Methanol 8.Repeat step 1 to 6 with Isopropilic acid. Data and Processing Alcohols Initial deal of microburner fill with alcohol (g) 0. 01 Final stilt of microburner fill with alcohol (g) 0. 01 Initial temperature of water(C) 0. 1 Final temperature of water(C) 0. 1 Volume of water in metallic calorimeter (cm3) 0. 5 Ethanol 5. 38 5. 08 23. 0 33. 0 one C. 0 Methanol 5. 33 4. 94 24. 0 34. 0 100. 0 Isopropoli c acid 5. 45 5. 20 24. 0 34. 0 100. 0 Find the mass of water ?=mv ? (density) H2O = 1. 0 g /cm3 Calculate % Uncertainty in mass of waterAs the mass of water is the same in the 3 alcohols the % scruple is the same for all the alcohols compulsory uncertainty of the measuring cylindermass of water ? 100 Calculating ? mass change (alcohols burned mass) (initial mass 0. 01 g)-(final mass 0. 01 g) Calculating parcel uncertainty in alcohol burned mass Absolute uncertainty of alcohols burned massalcohols burned mass ? 100 Calculate the percentage uncertainty of alcohol burned moles percentage uncertainty of alcohol burned mass+percentage uncertainty of alcohols molar mass Calculating ?H (enthalpy change) ?H=-mass of water x specific oestrus of water x ? T of water mol of alcohol * The specific heat for water is 4. 18 =1004. 184x 10=4,184 J or 4,184 KJ exothermic Methanol= * H2O = 100 ml * mH2O= 100 mg * t1 H2O= 23C Mass (i) methanol= 5. 38g * tf= H2O=33C Mass (f) methanol= 5. 08 g ?T = TF-TI= ?T= 10C Calculating mass change ?m=mi-mf= 5. 38-5. 30=0. 30g ?m=? mMr=0. 3032. 04=0. 009 mol ?H=-4. 1840. 009=-464888. 9jmol % uncertainity(balance)=0. 020. 30x 100=6. 67 % % uncertainity(thermometer )=110x 100=10 % %error=-726000-(-464888. )-726000x 100=36% Qualitative Observations We could deliberate from the burn of methanol that the flame owas of color orange red, barely therewere not dirt in the bottle. Ethanol * H2O = 100 ml * mH2O= 100 mg * t1 H2O= 24C Mass (i) ethanol= 5. 33 g * tf= H2O=34C Mass (f) ethanol= 4. 94 g ?T= TF-TI= ?T= 10C Calculating mass change ?m=mi-mf= 0. 39 g 5. 33-4. 94= 0. 39 g ethanol 0. 3946. 07 g/mol=0,008 mol ?H=-4. 1840. 008=-523,000jmol % uncertainity(balance)=0. 020. 39x 100=13 % % uncertainity(thermometer )=110x 100=10 % %error=-1360000-(-523000. 0)-1368000x 100=61. % Qualitative Observations We can observe a lost of weight during the experiment, more(prenominal)over the flame was orange blue but with a big strong orange , it didnt burn complete therefore show dirt in the cup. Isopropolic acid * H2O = 100 ml * mH2O= 100 mg * t1 H2O= 24C Mass (i) = 5. 45 g * tf= H2O=34C Mass (f) ethanol= 5. 20g ?T= TF-TI=10 c ?m=mi-mf= 0. 25 g Isopropolic acid 0. 25 60,1g/mol=0,004 mol ?H=-4. 1840. 04=-1,046,000jmol % uncertainitybalance=0. 020. 25x 100=8% % uncertainity(thermometer )=110x 100=10 % %error=-2006. 9-(-1046. 0)-2006. 9x 100=47. 9% At last, the alcohol used was Isopropilic acid. The flame with this alcohol was the strongest flame, it was very strong, was very yellow at the carrousel and blue at the bottom. * We could also notice that all the 3 alcohols produced Soot. (is a general term that refers to bastardised light speed particles resulting from the incomplete combustion) Conclusion = As we know the finality of the lab was to find the enthalpy change in the three alcohol methanol, ethanol and isopropyl alcohol.. Enthalply change is to see or measure up the toal zippo of thermodynamic system.Focusing in the resul t we got the actual enthalpy change with a smaller value in the theoretical this is because during the experiment there was a lot of energy lost mostly in the heat . the percentage of uncertainty could be also emphasize that the heat was lost due to we didnt accumulate in precise way the distance between the flame and the micro burner, and percentage error was in high spirits because the heat was transfereedto the materials in the system not only to the water . Moreover from the qualitative observations we could conclude give away it there was a complete or incomplete combustions.Methanol got a complete combustion since there was no soot under the cup,therefore carbol dioxide was realeased. 2CH4O (1) + 3O2 (G) = 2CO2(g) + 4H2O (I) Ethanol case was different we see that some sootappeared in the cup, therefore carbon dioxide and carbon monoxide . C2H6O (I)+ 3O2(G)= 2CO2 (g)+3H2O (I) C2H6O (I)+ 3O2(G)= 2CO(g)+3H2O (I) Isopropilic Acid ,there was soot produced in the experiment, ther e was a incomplete combustion there was more carbon moxide produced than carbpn dioxide Errors Complete combustion was not completed because of the lack of oxygen available.The micro burner had a slim wick which affects the intensity of the flame The distance between the micro burner and the metallic calorimeter varies. So its no a fair experiment Heat was lost to the surrounding and the aluminum cup absorbed some of it. Improvements social occasion aluminum foil for a next trial to keep the flame and the base of the cup insulated from the surroundings. Measure an exact distance and keep it constant for all trials. For a next trial uses a yearlong wick that will provide a more intense flame that wont run show up Try to provide an adequate oxygen supply that would be suitable for lab conditions.