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Video instructions and help with filling out and completing Who Form 2220 Calculator

Instructions and Help about Who Form 2220 Calculator

In this video we'll calculate an enthalpy our chemical reaction process the one that I've selected is that we're going to be of butane gas because butane is a hydro does contain quite a bit of chemical potential energy so when it reacts with oxygen this energy can be given off in an exothermic process the products of the reaction are going to be carbon dioxide and water and because there's quite a bit of energy given off we can record that here now in this problem we're actually going to calculate the exact amount of energy given off by this reaction process in order to do that we need to have this value right here now this is telling us that we are looking at the change in enthalpy for combustion of butane the value for this is two thousand eight hundred seventy seven point five kilojoules per mole so this is referring to if we burn one mol of butane how much energy is going to be given off the negative sign here is actually telling us that this is an exothermic process where the energy content of the products is going to be lower than the energy content of the reactions so the enthalpy change is going to be negative again if we were to interpret an energy diagram we can see that the energy content for butane would be at a higher point the energy content of the products the carbon dioxide and water is at a lower level so when we calculate Delta H it would actually work out to be a negative value again this is letting us know that we're looking at an exothermic reaction process this problem really boils down to doing some simple dimensional analysis in order to do that we are going to need to convert the mass of butane to be combusted from point 1 3 grams to a number of moles in order to do this we'll need to know the molar mass of butane so we've calculated the molar mass for butane that works out to be 58 point one four grams per mole again this is calculated by using the subscripts from the chemical formula because carbon has four atoms present in a butane molecule we're going to do twelve point zero one the mass of carbon multiplied by 4 to get forty eight point zero four massive hydrogen one point zero one will be multiplied by 10 because there are 10 atoms of hydrogen present in a butane molecule my first step will be to convert from of butane two moles of butane we'll use this value two thousand eight hundred seventy seven point five kilojoules per mole I did decide to leave out the negative sign in front of this value that's really a preference thing I know that this is an exothermic process so I know that the energy I'm calculating is going to be energy given off it may be the case that you'll be asked to report a negative value here again a negative value just indicates that the energy is being given off by the reaction process completing the calculation we're able to determine that there are six point four kilojoules of energy which are going to be released by this process again I'm going to indicate that this is an exothermic process by saying that the kilojoules of energy are being released another way of doing this would be to report a value of negative six point four kilojoules indicating that the overall energy of the products is going to be lower than where the reactants started.