Question

1. consider the thermochemical equation for the combustion of acetone (c₃h₆o), the main ingredient in nail polish remover: c₃h₆o(l) + 4 o₂(g) → 3 co₂(g) + 3 h₂o(g)δᵣh° = -1790 kj mol⁻¹. if a bottle of nail polish remover contains 177 ml of acetone, how much heat is released by its complete combustion? the density of acetone is 0.788 gml⁻¹.

Explanation:

Step1: Calculate the mass of acetone

Use the density - volume formula $m=
ho V$. Given $
ho = 0.788\ g/mL$ and $V = 177\ mL$.
$m=0.788\ g/mL\times177\ mL = 139.476\ g$

Step2: Calculate the molar mass of acetone

The molar mass of $C_3H_6O$: $M=(3\times12.01 + 6\times1.01+16.00)\ g/mol=58.08\ g/mol$

Step3: Calculate the number of moles of acetone

Use the formula $n=\frac{m}{M}$.
$n=\frac{139.476\ g}{58.08\ g/mol}=2.4014\ mol$

Step4: Calculate the heat released

From the thermochemical equation, $\Delta_rH^{\circ}=- 1790\ kJ/mol$. The heat released $q = n\times\Delta_rH^{\circ}$.
$q=2.4014\ mol\times(-1790\ kJ/mol)=-4298.506\ kJ$

Answer:

The heat released is $4299\ kJ$ (rounded to four - significant figures).