00:01
So let's do this chemistry problem, but before i get started, i recommend that you do the question yourself and come back to see if you got it right or not.
00:10
So hopefully you've done the question now.
00:12
Let's work on it together.
00:13
So we want to find, we want to use the standard enthalpy of formation and find the molar enthalpy of combustion of pentane to produce carbon dioxide and water.
00:24
So to do this, the first step that we should do is right down the reaction that is occurring.
00:30
Pentane is c5h12 and when combustion is occurring we always have to add oxygen and of course during always during combustion there is co2 carbon dioxide and water okay now we need to balance the reaction so it's gonna be eight six yeah that looks about right and to figure out the standard enthalpy or you to figure out the molar enthalpy we need to use this formula so of products minus the total standard enthopia of formation so the reactants in this case is pentane and oxygen and the products are carbon dioxide and water so you can use your standard table of values but the so the standard and top of the change of formation for pentane is minus 4, 146 .8 kilojoules per mole.
01:54
And the enthalpy of formation for oxygen is zero because when we're finding the standard enthalpy formation, their elements are always zero.
02:04
So you could just write it down or you could even just leave it down.
02:08
I can write it down here for clarity.
02:09
And the standard enthalpy formation for carbon dioxide is minus 393 .5...