Question

A new grill has a mass of 30.0 kg. you put 1.5 kg of charcoal in the grill. you burn all the charcoal and the grill has a mass of 30.0 kg. what is the mass in kg of the gases given off? (assume that the charcoal is pure carbon solid and that it burns completely in oxygen).

Answer 1

The reaction for burning of charcoal or complete combustion is as follows:

$C(s)+O_{2}(g)\rightarrow CO_{2}(g)$

From the above balanced reaction, 1 mole of carbon releases 1 mole of $CO_{2}$ gas.

Converting mass of charcoal into moles as follows:

$n=\frac{m}{M}$

Molar mass of pure carbon is 12 g/mol thus,

$n=\frac{1.5\times 10^{3} g}{12 g/mol}=125mol$

The same moles of $CO_{2}$ is released. Converting these moles into mass as follows:

m=n×M

Molar mass of $CO_{2}$ is 44 g/mol thus,

$m=125mol\times 44 g/mol=5.5\times 10^{3}g$

Converting mass into kg,

$1g=10^{-3}kg$

Thus, total mass of gas released is 5.5 kg.