Question

Consider the thermochemical equation for the combustion of acetone (C3H6O), the main ingredient in nail polish remover.

C3H6O(l)+4O2(g)→3CO2(g)+3H2O(g)ΔH∘rxn=−1658kJ​

If a bottle of nail polish remover contains 143 mL of acetone, how much heat is released by its complete combustion? The density of acetone is 0.788 g/mL.​

Answer 1

  acetone has molar mass = 58.08 g/mole...

143 mL x (0.788 g / mL) x (1 mole / 58.08 g) = 1.94 moles acetone

C3H6O(l)+4O2(g)→3CO2(g)+3H2O(g)

from the balanced equation...1 mole of acetone releases +1658 kJ of heat upon combustion.

1.94 moles x 1658 kJ/mole = 3294.37 kJ

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that value is +... not negative. the negative sign is for the reaction and indicates that 1790 kJ are "released" by the combustion of 1 mole of acetone. if you say -3294.37 kJ are released, that means 3294.37 kJ are absorbed. That wasn't the case...