The enthalpy of combustion of gasoline (C8H18) is 5471 kJ mol-1. How much heat will be produced by burning 1 gallon of gasoline at 25°C? (Density of gasoline = 0.703 g/mL; 1gallon = 3.78 L) Show your work clearly.

127529 KJ

Explanation:

Since 1gallon = 3.78 L= 3780 ml

The density of C8H18= 0.703 g/mL

Density = mass/volume

Mass= Density × volume

Mass= 0.703 g/mL × 3780 ml

Mass= 2657.34 g

Molar mass of C8H18= 114 g/mol

Number of moles= mass/molar mass

Number of moles= 2657.34/114

Number of moles= 23.31 moles

Since 1 mole evolved=5471 kJ

23.31 moles = 5471 kJ × 23.31 = 127529 KJ

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

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