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chemistry:enthalpy changes and moles

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ruby92:
1)A typical jumbo jet burns fuel at a rate of 200kg per minute assuming jet fuel is c11h24 what mass of water does the jumbo jet produce per minute?

2)(a) calculate the bond enthalpy of the N-H bond in NH3 using the data given below.
N2+3H2 (reversible reaction sign) 2NH3   DetaH=-92kj/mol

N(triple bond)N has a bong enthalpy of 946
and h-h bond has a bond enthalpy of 436

b)The enthalpy of formation of N2H4 is 94kj/mol
using the N-H bond enthalpy derieved in (a), calcualte the bond enthalpy of N-N bond

nid404:
1) Complete combustion of C11H24

2C11H24 +17 O2 ----> 11CO2 + 12 H2O

1 mole of C11H24= (11X12) + (24X1)=156g
no of moles in 200000g=1282moles

2moles of fuel is to 12 moles of water
1282 moles= 1282X12/2
                =7692moles
1mole of water=18g
7692moles=138462g= 138.5kg (approx)

nid404:
2)  N2=+946 kjmol-1
     3 H-H= 3X436=+1308kj

Enthalpy of the reactants=2254

Enthalpy change= -92kj/mol

Bond breaking-bond making=-92
2254- bond making=-92
bond making=2346kj for 6N-H bonds(since it's 2NH3)
so for 1 N-H bond 2346/6=391kj/mol

nid404:
 N2+ 2H2---->N2H4
946               + 2X436                                X

1818-X=+92
X=-92+1818=1726

1726=4N-H + N-N
       =4X391  + Z

Z=1726-1564=162kj/mol

ruby92:
in the 1st question the balancing is wrong.
there are 22 C on the left side whereas only 11 on the right?

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