I've done this and I got -10148.2KJ, but it kind of seems like a large numberThe next part of the question I have to find the heat produced when 1.00L of octane is burnedOctane has a density of 730g/LI did this by first finding the mass, and then converting this to molesThen I used HnHr, and the answer I got was -62 411.43 KJI'm pretty sure I've gone completely wrong at this pointThe last part of the question you have to find the mass of octane to raise the tempof an aluminum engine block from 15.0Celcius to 85.0 CelciusThe engine block has a mass 110.0kg, the specific heat capacity is 0.900KJ/g, and only 20% of the heat produced is used to heat the engine blockSo far I've used Qmct, and got 6930KJ, multiplied that by 20%, and got 1386kJI'm not sure how to go forth after this pointIf anyone could check my answers, and help figure out how to do this question it would be much appreciated.
depends how strong u r lol (btw i didnt read wut u wrote i only read da title)
I went to Chem Eng classes a long time ago, so I know SAE unitsBut let's see how far I getLast one first: 242 lb aluminum block, Cp of Al 0.21 Btu/lb-F15-85C delta Temp of 126FSo 242x.21x1266403 BTUsWhich is 6,755 KJn-Butane has a heat of combustion of 21,308 BTU/lb, n-Pentane 21,091, n-Hexane 20,940 (Perry's Chemical Engineering Handbook, Table 9-30)Following that curve through n-Heptane to N-Octane, I'd estimate octane at 20,780 BTU/lb gross (assumes the produced water vapor condenses)So let's use net (leaves water as vapor), subtract 1,500 and get 19,280 BTU/lbNeed 6402 BTUs, divide by 19,280 BTU/lb 0.332 pounds or 150 gramsdivide by 0.730g/l 206 ml of octane to heat the engine blockIf only 20% goes to block heating, then 206ml/0.20 1.03 liters of octaneSecond one: liter of octane 730 grams 1.6 pounds x 19,280 BTU/lb 31,000 BTUs divide conversion factor of 9.478E-4 BTU/J 32,700,000 JoulesBut you're at 62,000,000 joulesLike a factor of two offFirst one: heat of combustion of octane -5508.9 KJ/mol (see reference below) 730 g / 114 g/mole 6.4 moles One liter then gives 6.4 x 5509 -35280 KJ which is close to what I got above.
