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Consider the following equation for the combustion of acetone (C3H6O), the main ingredient in nail polish remover.
C3H6O(l)+4O2(g)→3CO2(g)+3H2O(g)
ΔHrxn=−1790kJ

a) If a bottle of nail polish remover contains 158 g of acetone, how much heat would be released by its complete combustion?

Octane (C8H18) is a component of gasoline that burns according to the following equation:
C8H18(l)+252O2(g)→8CO2(g)+9H2O(g)
ΔH∘rxn=−5074.1kJ

a) What mass of octane (in g) is required to produce 1950 kJ of heat?

Respuesta :

baraltoa

Answer:

a) 4869 kJ will be released

b) 43.86 g of octane

Explanation:

The heat of combustion is the amount of heat released when 1 mol of a substance reacts with enough oxygen .

Since the heat of combustion  is per mol of combustible  substance what we are required to do in  this problem is calculate number moles in the reactions although in a different manner.

a) MW C3H6O = 158 g/mol

mol C3H6O = 158 g x 1 mol/58.08 g = 2.72

-1790 kJ/ mol x 2.72 mol = 4869 kJ

b) Here we are asked the mass of octane to produce 1950 kJ of heat knowing that per mol of octane we get 5074.1 kJ, then

1 mol / 5074.1 kJ   x  1950 kJ = 0.384 mol

mass C8H18 = 0.384 mol x 114.23 g/mol = 43.86 g

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