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

Experiment to Compare the shake up content Changes of Combustion of different AlcoholsIntroduction This plan will try to outline how the experiment of analyze changes of combustion of different alcohols will beconducted and what results are expected.BackgroundWhen chemic reactions give out they are often accompanied by capability changes.Chemical reactions most frequently occur in open vessels. That is,they adopt place at continuous pressure. Enthalpy refers to zero atconstant pressure (volume whitethorn vary).EnthalpyAn example is best to illustrate to level enthalpy works. Methane -how much energy does its molecules contain? The first thing essential isthe come of methane present = 1 mole (16 g). What ever its value,the count amount of energy in a disposed(p) amount of a contentedness (sometimescalled the Heat energy content) is getn as the enthalpy, denoted H.Methane is a fuel to hold energy from it, react it with type O.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 workable to know the total enthalpy (heat 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 deliberate experimentally, or calculated using Hesss rightfulness (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, make them to warm up. In this case thereactants concur more stored energy (greater total enthalpy) than theproducts. Such chemical reactions are give tongue to 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. some 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.