Hi folks, how are you doing?
I was wondering what this expression really means[the headline of this thread].
I have seen a lot of tv advertisements, newspapers articles and car sellers shops/manufacturers with this and similar information about CO-2 emissions.
If you make the following estimation---->
120g/Km, that means a gas output/emission of 120 gramms every 1000 meters, if the car rides with a full tank, let´s say, 1000Km, the emissions would increase by 1000, which gives us 120g by 1000 times equals 120.000 g
which means 120 kg of gases. Is this correct? It seems to me too much gases. I thought gases would weight much less than this.
Any comments about this? Any chemist around?
Cheers!

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If I remember correctly a mole of gas at atmospheric pressure and 0 degrees C occupies 22.4 liters. I have a feeling CO2 molecules are in that form - 44 grams per mole or about 1.96 grams per liter. So 120kg of CO2 occupies about 60,000 liters or 60 cubic meters. That's a fairly large roomful (of a house). Most gas tanks won't drive a car 1,000 kilometers, though. I doubt that I could go even 500km in my Ford Focus.

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