Short answer: Just short of 11.5 kg.

How do I know that? Well, we have to make some assumptions.

1. that charcoal is 100% carbon.

2. that the reaction is a complete combustion of coal with oxygen in the air into carbondioxide.

With these out of the way it's pretty straight forward. We need to first establish the balanced reaction:

C(s) + O22(g) -> CO22(g)

Well that was simple enough. So one can see that there is a one-to-one molecular relationship between carbon and oxygen.

Next we need to establish how many carbon atoms there are in 1 kg coal. To reduce the size of the number one normally uses the unit mol instead (1 mol is about 6.022×102323). In the periodic system we can see that 1 mol carbon weighs 12 grams (it is in fact how we establish what one mol is). We call this number the molar mass,M.It's relatively easy to see that there is a relationship between mass,m, number of moles,n,andM:

n = m/M.

In the periodic table we also see that molar mass of oxygen is 32 g/mol (2 oxygen atoms per molecule).

We know from the balanced reaction formula thatnof C equalsnof O22but from the relation above we can also write this as: