A new grill has a mass of 30.0 kg. You put 3.0 kg of charcoal in it. You burn all of it and the grill has a mass of 30.0 kg. What is the mass of the gases given off?
Answer with work, if possible.
2007-08-15 03:51:43 · 7 answers · asked by aaadaj 1 in Science & Mathematics ➔ Chemistry
Two will do.
2007-08-15 03:58:17 · answer #1 · answered by havanadig 6 · 0⤊ 2⤋
Charcoal is essentially carbon. So it has a molecular weight equal to that of carbon, ~12.
Charcoal burns, combining with oxygen to form CO2. CO2 has a molecular weight of 44 (12 for the carbon and 16 for each of the two oxygens).
Since the weight of the grill doesn't change, that says no residue is left behind, so all of the charcoal was burned.
The starting mass (3 kg) times the ratio of the product to the starting material (44/12) = the mass of the gas given off, 11 kg of gas.
Realistically, the charcoal isn't pure carbon, but it is probably 95-98% carbon, and it probably doesn't burn to CO2 with 100% efficiency, some of it likely forms CO (carbon monoxide), but unless you know the ratio of CO to CO2 and what the impurities actually are, then 11kg is as close as you will get.
2007-08-15 11:11:38 · answer #2 · answered by William 3 · 0⤊ 0⤋
its tempting to say 3kg but that would be wrong because the mass of the gas given off would also include the mass of the oxygen.
combustion of carbon(charcoal)
goes as follows:
C + O2 -> CO2
so to work out the mass of CO2 given off
compute the number of moles of carbon
3kg = 3000g
molar mass of carbon =12
moles of carbon = 3000/12 = 250 moles
so number of moles of oxygen = 500 moles
molar mass of oxygen =16
so total mass = 250*12 + 500*16 =11000g = 11kg
now this is only the case if all the charcoal is converted into CO2, in reality there will be unburnt carbon(soot) and maybe some CO there aswell.
2007-08-15 11:05:40 · answer #3 · answered by Mike 5 · 3⤊ 0⤋
Assuming the charcoal is pure carbon, and combustion is complete (ie, Carbon dioxide formed, and no carbon monoxide or carbon soot) - actually unlikely, but still:.
C + O2 = CO2
Atomic weight carbon =12
Atomic weight oxygen = 16
Molecular weight CO2 = 12 + 16 + 16 = 44
Therefore 3kg C reacts with (32/12)*3 = 8kg O (4kgO2)
(Ratio of oxygen to carbon in CO2)
Therefore weight of CO2 gas is 8 + 3 = 11kg
Note that the 30kg weight of the grill is irrelevant - we are only concerned with the 3kg of charcoal.
2007-08-15 11:03:19 · answer #4 · answered by AndrewG 7 · 4⤊ 0⤋
Assuming that all charcoal is pure Carbon it should get converted to CO2 gas. The mass of CO2 given off can be worked out as below:
mass of CO2 = 30*44/12 = 110 Kgs
2007-08-15 11:00:18 · answer #5 · answered by Bhaskar N 2 · 0⤊ 3⤋
3 kg of charcoal will still have a mass of 3 kg even after it is converted to gases. Density and weight will change, but the mass remains constant.
2007-08-15 11:07:59 · answer #6 · answered by The Electro Ferret 4 · 0⤊ 2⤋
i guess 1 kg
2007-08-15 12:17:28 · answer #7 · answered by sathyu 1 · 0⤊ 0⤋