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Physical Chemistry

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2 Mar 2008 17:56:05 IST

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an initiate mixture of Fe₂CO₃, and aluminium,Al, is used in solid fuel rockets. calculate fuel value per gram and fuel value per cc of the mixture. heat of formation and densities are as follows:

H _f (Al₂O₃) = 399kcal/mol

H _f (Fe₂O₃) = 199kcal/mol

density of Fe₂O₃ = 5.2g/cc

density of Al = 2.7g/cc

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Akhil

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Joined: 17 Jan 2008

Posts: 1451

2 Mar 2008 18:28:07 IST

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Fe₂O₃+2Al---->Al₂O₃+2Fe

mol wt of Fe2O3=160 g
and 2 Al is 54 g

also heat evolved per mole
=399-199=200 kcal/mole

204 g of reacting mixture( 1 mole FE2O3 and 2 moles Al) gives 200 kcal energy
so efficency per gram=200 kcal/204=0.98 kcal/gram

160 g Fe2O3 is 160/5.2 cc=30.77 cc
and 54 g Al is 52/2.7=20 cc

so we have 50.77 cc mixture giving 200 kcal..
1 cc gives 200/50.77=3.93 kcal/cc

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