Effect of Carbon Atoms Number in Alcohol on Combustion

Effect of Carbon Atoms Number in Alcohol on CombustionResearch QuestionHow does the fleck of coulomb paper corpuscles in the hydrocarbon range of mountains of primary inebriant affect its enthalpy permute of fire? commutative VariableThe independent variable in this investigation is the sum of carbon atoms in the hydrocarbon chain of primary alcoholic drink. Five different primary alcohol allow be phthisisd, namely, methanol, ethanol, propan-1-ol, butan-1-ol and pentan-1-ol.Dependent VariableThe dependent variable in this investigation is the enthalpy compound of burn of primary alcohol.Enthalpy assortment of combustion is the energy released when one mole of fuel is completely fire in oxygen to form carbon dioxide and piss. To pass judgment the enthalpy kind of combustion, the heat given out during combustion is first absorbed by pee which is calculated by q = mc T where m is the mess of pissing, c is the specific heat capacity of wet and T is the temperature diversity of water. The heat given out is then divided by the number of moles of alcohol used during the investigation. As combustion is an ex new(prenominal)mic reaction, a contradict sign is added to give the terminal enthalpy change of combustion.Control VariablesThe card below shows the variables that have to be controlledHypothesisThe higher the number of carbon is in the hydrocarbon chain, the greater the enthalpy change of combustion of the primary alcohol. 1 of the evidence for this hypothesis comes from the IB chemistry entropy booklet. The foundationard enthalpy change of combustion for methanol, ethanol, propan-1-ol and butan-1-ol are 726 kJmol-1, 1367 kJmol-1, 2021 kJmol-1 and 2676 kJmol-1 1respectively.Another way to get this trend is to use the average bond enthalpy to estimate the enthalpy change of combustion. though average bond enthalpies are just average values only, they do give an insight on the trend of the enthalpy change of combustion of different al cohol. The general formula for alcohol is CnH2n+2O. The general equation for combustion of alcohol isCnH2n+2O (l) + 1.5nO2 (g) nCO2(g) + (n+1)H2O(l)When the number of carbon increases by one, the following sidestep shows the otiose bonds to be broken and extra bonds formedThe average bond enthalpies for the to a higher place bonds are shown in the table below 2The net change in enthalpy change when one more carbon is added= + 2 413 + 347 2 746 2 464= 1247 kJmol-1Thus, the enthalpy change of combustion of primary alcohol will decrease by 1247 kJmol-1 (more negative) when one more carbon is added to the hydrocarbon chain.Apparatus vitamin C cm3 measuring cylinder (1 cm3) 6 (one for separately alcohol and the other for water)(2 d.p. ) Electronic balance (0.01 g) 1Tripod 1Copper container with lid 15 (one for each trial)Stand and clamp 1 (use to hold the thermometer in position) hectogram in glass thermometer (0.1C) 2 (one is used to mea accepted temperature of water an d the other used for monitoring the temperature of surrounding)Stirrer 1Aluminium heat buckler 4 (to reduce heat loss)Spirit burner with wick 15 (one for each trial)Lid 1 (for extinguishing the flame)Stopwatch (0.01 s) 1Ruler (0.1 cm) to measure the length of wire and the position of the thermometerScissor 1 (used to cut the wick)Chemicals750 cm3 of distilled water (50 cm3 for each trial) atomic number 6 g of each of the following primary alcohol at a concentration of 90%.Methanol, ethanol, propan-1-ol, butan-1-ol and pentan-1-olProceduresPrepare a feeling burner. Cut the length of its wick to approximately 3.0 cm (the portion away the burner) with a pair of scissors and a swayer.Measure 50 cm3 of methanol with a 100 cm3 measuring cylinder and pour it in a nitty-gritty burner.Weight the impression burner with an electronic balance. Record the slew of the spirit burner in the table below.Measure 50 cm3 of distilled water with another 100 cm3 measuring cylinder and pour it in a copper container. determine the copper container on a tripod and cover it with a lid.Use stand and clamp to hold a thermometer in the beaker of water. Use a ruler to make sure that the bottom of the thermometer is 1.0 cm from the bottom of the beaker and make sure the thermometer is approximately located at the centre of the beaker. Record the initial temperature of the water and put it in the table below.Place a stirrer in the water. Stir the water throughout the process of heating.Surround the whole setup with heat shield made of aluminium to reduce heat loss. throw a fit the wick of the spirit burner with a lighter.Place the spirit burner under the beaker. instanter start the stopwatch and wait for two minutes.Stop the stopwatch later two minutes.Use a lid to extinguish the flame.Record the highest temperature reached by the thermometer and put it in the table below.Allow the spirit burner to cool.Weigh the final examination plenitude of the spirit burner with an electr onic balance. Put the mass in the table shown below.Repeat the experiment (Step 1 to 16) two more times.Repeat the homogeneous experiment (Step 1 to 17) for other primary alcohols (i.e. ethanol, propan-1-ol, butan-1-ol and pentan-1-ol).Table for recording crank data and some processed dataData ProcessingThe mass of fuel used (m) is calculated by subtracting the final mass of spirit burner from the initial mass of spirit burner.The temperature change (T) is calculated by subtracting the final temperature by the initial temperature.The heat (q) absorbed by water provoke be calculated by the formulaq = mc Twherem is the mass of water used 50 g (as the density of water is 1 g cm-3)c is specific heat capacity of water 4.18 Jg-1K-1Number of moles of fuel used can be calculated by dividing the mass of fuel used (m) by the hoagy mass of the fuel.The molar mass is found by adding up the relative atomic mass of the element involved. For example, the molar mass of methanol (CH3OH) is 12.01 + 4 1.01 + 16.00 = 32.05 gmol-1.The enthalpy change of combustion of alcohol is found by dividing the heat by the number of moles of fuel with a negative sign added to show that it is exothermic.A interpret is plotted with enthalpy change of combustion (y-axis) against the number of carbon atom is the hydrocarbon chain of the primary alcohol (x-axis).Compare this graph with the graph in the hypothesis.SafetyAlcohols are flammable. Avoid naked flame near alcohol.1 Chemistry data booklet (First examinations 2009). United Kingdom International Baccalaureate, 2008. Print.2 Chemistry data booklet (First examinations 2009). United Kingdom International Baccalaureate, 2008. Print.