Effect of an Increase in Molar Mass on Enthalpy Change

Effect of an Increase in hero sandwich host on Enthalpy ChangeAn investigation to determine the effect of an increase in molar potty on the enthalpy alte balancen of combustion of fuels method VariablesIndependent VariableMolar battalion (type) of intoxicant.Dependant VariableThe succeeding(a) variable leave alone be observed and paced* Mass of the alcohol apply.Controlled VariableThe following variables pull up stakes need to be controlled* Mass of piddle, the volume of piss allow for be measured using a meat cylinder.* Amount of wick on burner, the amount of wick on the burner will be measured using a radixard ruler and unploughed constant as it affects the amount of alcohol burnt.* Height of beaker above flame, the beaker will be situate up so that the founding just touches the flame.* display case of beaker, the alike(p) beaker will be apply and marked, as the density and coat of the beaker affect the amount of pepperiness energy transferred to the water .* Agitation of the water, the water will need to be stirred in every experiment as to prevent any anomalous results.* Temperature change is held constant, measured with a thermometer drill from -10oC to 110oC, with an uncertainty of 0.5oCMethod Procedure1. Measure one Ccm3 of water in the amount cylinder.2. Pour the water into the 250cm3 beaker and record its temperature.3. Choose a spirit burner. interpret the name of the fuel, and the masses of the whole burner (including the hat and fuel inside).4. Clamp the beaker, and set it up so that the spirit burner will fit comfortably nether it.5. Light the 6mm wick of the spirit burner, and put it under the 250 cm3 beaker.6. Stir the water gently with the thermometer, and watch the temperature.When it has increased by 20C, put the lid on the spirit burner to put the flame come forth.7. Record the new mass of the whole burner (including the lid and fuel inside).8. Using fresh water separately time, repeat the experiment at least tw ice with the alike fuel.9. twin all for different fuels.ResultQuantitative raw data force out NameExperiment 1Experiment 2TemperatureMass originally/g (0.01)Mass After/g (0.01)Mass Before/g(0.01)Mass After/g(0.01)Before/oC (0.05)After/oC(0.05)Methanol181.48180.00179.79178.2220.0040.00 neutral spirits215.64214.50214.52213.5020.0040.00Propan-1-ol228.70227.39227.39225.9120.0040.00Butan-1-ol174.63173.96173.96173.3420.0040.00Pentan-1-ol172.33171.47171.47170.8420.0040.00Octan-1-ol218.77217.72217.72216.8520.0040.00Observations during Experiment every last(predicate) receptions were exothermic as the beaker and the surrounding began to warm up. arouse NameObservationMethanolIt burnt with a short smear orangey yellow flame. The give of the beaker was partly covered with soot. handsome bubbles make at the base of the beaker. neutral spiritsIt burnt with a pale orangey yellow flame. The base of the beaker was slightly darkened by the physical composition of soot. Small bubbles fashio n modeled at the base of the beaker.Propan-1-olIt burnt with a thin bright orangey yellow flame. The base of the beaker was again slightly darkened by the organization of soot. Small bubbles formed at the base of the beaker.Butan-1-olIt burnt with a contract and huge chickenhearted orange flame. The base of the beaker was considerably darkened by the formation of soot. Small bubbles formed at the base of the beaker.Pentan-1-olIt burnt with a narrow and long yellowish orange flame. The base of the beaker was completely darkened by the formation of soot. Small bubbles formed at the base of the beaker.Octan-1-olIt burnt with a narrow and long distinct yellow flame. The base of the beaker was fully obscured by the formation of soot. Small bubbles formed at the base of the beaker.AnalysisThe heat that is released in the combustion of an alcohol is absorbed by the liquid. The temperature change of the liquid is because related to the heat of combustion of the alcohol (heat released in a reaction (combustion in this case) = heat gained by the substance). I can work out the heat energy absorbed by the liquid using the sayingHeat Energy transferred (Q) = mcTc = limited heating capacity of water (4.18 Jg-1K-1)m = mass of water (in grams)T = change in temperature of the water.And find the enthalpy (heat) change of combustion per separate of a mole of the alcohol.For exampleMass of water (m) = 100g (0.5), Change in Temperature (T) = 20.00C (0.10)Therefore, Heat Energy Transferred (Q) = mcT (degree of uncertainty)= 100 4.18 20 (0.5 + 0.10) = 8360 J (0.6) = 8.36 kJ (0.6)This is the same for every reaction as the mass of water remains constant.From here on, I can calculate the enthalpy change per fraction of a mole of the substance as it combusts to form its productsHcAlcohol + Oxygen Carbon Dioxide + WaterMass of Methanol used = 1.52g (0.02) good turn of moles (N) = M/RMM ( lot degree of uncertainty)= 1.52g / 32.04g (2.00% + 0%) = 0.0474 mol (2.00%)Where,M = Mass o f the Alcohol used to heat the amount of waterRMM = Relative Molar Mass of the Alcohol obtained from the data book, so the percentage uncertainty is 0% Enthalpy change of flame (Hc) = Q/N (percentage degree of uncertainty) = 8.36 kJ / 0.0474 mol (7.17% + 2.00%) = 176.22 (9.17%)All calculations are done similarly.fire NameAverage Initial mass/g (0.01)Average Final mass/g (0.01)(M) Mass used/g (0.02)(T) Temp change/C (0.10)(Q) Heat Energy Transferred/kJ (0.12)(N) Number of Moles used/mol (2.00%)(Hc) Enthalpy change of Combustion (9.17%) /kJ mol-1Methanol180.64179.111.5220.008.364.74 x10-2-176.22Ethanol215.08214.001.0820.008.362.34 x10-2-356.62Propan-1-ol228.05226.651.4020.008.362.33 x10-2-358.82Butan-1-ol174.30173.650.6520.008.360.88 x10-2-953.29Pentan-1-ol171.90171.160.7520.008.360.85 x10-2-982.58Octan-1-ol218.25217.290.9620.008.360.74 x10-2-1134.09ConclusionFrom the table it is evident that the molar mass of an alcohol increases the amount of heat energy it dispenses per fraction o f a mole. Also, the graph shows that thither is a positive correlation between molar mass and enthalpy change of combustion for alcohols. What could explain the relation is that as the molar mass increases there is an increase in the number of available carbon atoms to combine with atomic number 8 and release energy. Therefore, an increase in molar mass will book an incremental effect on the enthalpy change of combustion.EvaluationFuel NameLiteratureHc Value (LV)Experimental Hc Value (EV)Literature faulting(EV LV)/LV*100Methanol-726.00-176.2275.76%Ethanol-1367.30-356.6274.00%Propan-1-ol-2021.00-358.8282.24%Butan-1-ol-2675.60-953.2964.38%Pentan-1-ol-3328.70-982.5870.48%Octan-1-ol-5293.60-1134.0978.58%Table depicting the percentage hallucination of the experimental value from the actual value available in the data bookAverage Literature error 74.22%The results are non consistent with the literature value, all of the reactants did not completely combust ascribable to the lack of oxygen, leading to the formation of soot and carbon monoxide, which means that the heat output is less than it would feed been if all of the carbon burnt, since the calculations are found on the mass of the un-burnt carbon, the calculated value is less than the literature value. The beaker would not have transferred all the heat across some would have been lost in heating the beaker as well as the clamp and stand, this would have caused the value to be less than the actual value. Other possible sources of error could be by slight differences in the values of the fixed variables, standardized the mass of water not being exactly 100g, due to faulty demoing of the measuring cylinder caused by a parallax (when the scale is read at an angle to the nerve centre, as the light is refracted through the glass, the reading appears to be at a different position). The same error could have been as well made in the reading of the thermometer, causing there to be ill-timed temperature re adings. There were some anomalies when reading the graph as two values were almost identical. It could have been due to the amount of wick on the burner as it would not have been exactly the same (6mm) on each burner as this was difficult to measure. This would have caused differences in the amount of alcohol burnt. The flame was not always just touching the beaker, as this again was difficult to measure accurately, and would have caused differences in the amount of heat given off as the temperature of the flame is different at different heights. Also, the thermometer was not in the same place at each temperature recording, as even though the water was stirred, there would be differences in the temperature of the water at different depths.Errors mentioned in conducting ExperimentPossible corrections that could be madeIncomplete Combustion of reactantsPlacing the fuel in an line of productstight chamber and controlling the flow of air through valves as to make the correct stoichiome tric balance ratio of carbon and oxygen.Heat loss to the surroundingInsulation of the beaker, boss, clamp and stand by wrapping them with polystyrene. Also, Preventing any draught from carrying the heat energy away by placing a board to shield it.Parallax errorPosition of eye at all volumetric vessels must be at the same level as the meniscus.Transfer of heat energy to the liquidA calorimeter made of a better heat conducting material, perhaps something strong and lightweight like aluminium.