Enthalpy Lab

LAB OF heat content CHANGE IN COMBUSTION Objective Determine the Enthalpy mixed bag of combustion ? Hc of three different inebriantic drinks. Methanol, Ethanol and Isopropilic acid. Procedure 1. Fill the design micro have kittenser with Ethanol and weight it 2. Pour speed of light cm3 of urine into the aluminium cup 3. Arrange the cup a short distance all over the micro burner 4. Measure the temperature of peeing 5. When the temperature of the piddle has risen by 10C, record the temperature. 6. Reweight the microburner. Record 7. Repeat steps 1 to 6 however now with Methanol 8.Repeat step 1 to 6 with Isopropilic acid. Data and impact Alcohols Initial pickle of microburner contract with alcoholic drink (g) 0. 01 Final kitty of microburner fill with alcohol (g) 0. 01 Initial temperature of irrigate(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 vitamin C. 0 Methanol 5. 33 4. 94 24. 0 3 4. 0 blow. 0 Isopropolic acid 5. 45 5. 20 24. 0 34. 0 100. 0 expose the mass of water ?=mv ? (density) water system = 1. 0 g /cm3 count on % Uncertainty in mass of waterAs the mass of water is the same in the 3 alcohols the %uncertainty is the same for all the alcohols Absolute uncertainty of the step cylindermass of water ? 100 Calculating ? mass depart (alcohols burn mass) (initial mass 0. 01 g)-(final mass 0. 01 g) Calculating parting 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 variety show) ?H=-mass of water x specific heat 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 multitude (i) methanol= 5. 38g * tf= H2O=33C corporation (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 % % phantasm=-726000-(-464888. )-726000x 100=36% Qualitative Observations We could see from the burn of methanol that the burn owas of color orange red, moreover 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 lionize a lost of weight during the experimentation, moreover the flame was orange begrime d but with a big strong orange , it didnt burn cop 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 top and blue at the bottom. * We could also notice that all the 3 alcohols produced Soot. (is a general term that refers to impure vitamin C particles resulting from the incomplete combustion) outcome = 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 energy of thermodynamic sys tem.Focusing in the result we got the essential enthalpy change with a smaller value in the suppositious this is because during the experiment there was a lot of energy lost broadly speaking in the heat . the percentage of uncertainty could be also show that the heat was lost due to we didnt aggregate in small way the distance betwixt the flame and the micro burner, and percentage error was high because the heat was transfereedto the materials in the system not only to the water . Moreover from the qualitative observations we could conclude out 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 just about 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, there was a incomplete combustion there was more carbon moxide produced than carbpn dioxide Errors Complete combustion was not completed because of the lack of atomic number 8 available.The micro burner had a little 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 whatsoever of it. Improvements Use aluminum foil for a next trial to go along the flame and the base of the cup insulated from the surroundings. Measure an exact distance and persist in it constant for all trials. For a next trial uses a long-life wick that will provide a more intense flame that wont run out Try to provide an adequate oxygen supply that would be suitable for lab conditions.