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Ch.5 - Thermochemistry

Chapter 5, Problem 82c

Methanol (CH3OH) is used as a fuel in race cars. (c) Calculate the heat produced by combustion per liter of methanol. Methanol has a density of 0.791 g/mL.

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Hi everyone for this problem, we're told that hexane produces 4163 kg joules per mole of heat. When it undergoes combustion. We need to calculate the heat produced by burning five gallons of hexane and were given the density of hexane. So we're calculating heat. And so that means we want killer jewels and we're told that we have five gallons of hexane. So this is our starting point. So we want to go from five gallons of hexane, two killer jewels. Okay, so in order for us to do this, there's going to be a couple of things that we need to know. The first is that we need to know how many gallons there, how many leaders is in a gallon. So one gallon Is equal to 3.785 L. Okay, so let's start off by converting this to leaders. So one gallon Is 3.785 L. And we need to go from they gave us the density and mill leaders here. So if you take a look, we have g per middle leader. So in order to use this density, we need to convert from leaders two ml and one millimeter. We have 10 to the -3 leaders. So now we can use our density to go from gallons two g. Okay, so let's just take a look at what units, cancel our gallons, cancel our leaders cancel and we have mill leaders. So let's go ahead and plug in our density and one mil leader, There is 0. 594 g of hexane. Okay, so our mill leaders cancel here and now we want to we have grams of hexane. We want to go from grams of hexane, two moles of Exxon. And we can use that using the molar mass of hexane. So in one mole of hexane, Using the Molar Mass, we see that it is 86.2 g of hexane. And now we have moles of hexane because our grams cancel and we want energy produced. And if you see here, they tell us that hexane produces 4163 Killah jewels per mole. So now we are in units of moles of hexane. So now we can plug that in in one mole of vaccine. The energy produced is 4, killah jewels. Okay, so our moles cancel and we're left with a unit of kill a jewel. So when we saw this out are heat produced from burning this five gallons of hexane is going to be 6.03 times 10 to the 5th. Kill a jewels of heat. And this is our final answer. I hope this was helpful