Experiment to Compare the Enthalpy Changes of Combustion of Different Alcohols :: GCSE Chemistry Coursework Investigation

Experiment to Compare the enthalpy Changes of Combustion of diametric AlcoholsIntroduction This plan will try to outline how the experiment of comparison changes of combustion of different alcohols will beconducted and what results are expected.BackgroundWhen chemic substance reactions arrive at repoint they are often accompanied by animation changes.Chemical reactions most frequently occur in open vessels. That is,they light upon place at continuous pressure. Enthalpy refers to nada atconstant pressure (volume whitethorn vary).EnthalpyAn example is best to illustrate to try out enthalpy works. Methane -how much energy does its molecules contain? The first thing take isthe occur of methane present = 1 mole (16 g). What ever its value,the ingrained amount of energy in a disposed(p) amount of a centre of attention (sometimescalled the Heat energy content) is bashn as the enthalpy, de noned H.Methane is a fuel to doctor energy from it, react it with oxygen.CH4(g) + 2O2( g) CO2(g) + 2H2O(l)The above chemical equation shows that 2 moles (64 g) of oxygenmolecules are required to burn 1 mole of methane. Again, it isim executable to know the total enthalpy ( fondness energy content) of theoxygen. Likewise, we cant know the total heat energy content of 1mole of CO2 and 2 moles of H2O (the products).Enthalpy ChangeH = (HCO2 + 2HH2O) - (HCH4 + 2HO2)In general,H = Hproducts - HreactantsBut remember, this is theoretical it is not possible to determine theabsolute value of the enthalpy of a chemical element or compound.However, H values for chemical reactions can be obtained. They can be calculated experimentally, or calculated using Hesss legality (see later),or worked out in other ways.Exothermic and Endothermic ReactionsWhen chemical reactions take place they are often accompanied by heatchanges. The system (the reactants which form products) may give outheat to the surroundings, causation them to warm up. In this case thereactants acquire more stored energy (greater total enthalpy) than theproducts. Such chemical reactions are state to be exothermic. Thesystem may take heat from the surroundings, causing them to cool down.In this case the reactants have less stored energy (less totalenthalpy) than the products. Such chemical reactions are said to beendothermic.Exothermic reactions give out energy to the surroundings.Endothermic reactions take energy from the surroundings. almost reactions take place at constant pressure...It is possible to measure changes in heat energy that accompanychemical reactions. Most reactions take place in vessels that are opento the atmosphere, that is, they take place at constant pressure(volume may vary). The special name given to a change in heat energycontent measured at constant pressure is enthalpy change.