# Volume of gas from given weight of dry ice? Answered

I'm rusty on basic chem. specifically, molarity, molecular weight...

Dry ice, frozen CO2 is sold by the pound. I'd like to know by working formulas, how much volume a pound of dry ice will fill once it returns to gas.

Carbon has molecular weight ~ 12.  Oxygen ~16.  But I don't recall what those numbers represent.

One mole of gas occupies 22.4 liters, but how much does a mole of CO2 weigh?

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## Discussions

@verence has it correct
* one mole of CO2 weights 2x12+16~44g (https://en.wikipedia.org/wiki/Carbon_dioxide)
* one kg of CO2 (whichever CO2 physical form - no effect whatsoever on its mass) contains therefore 1000/44~22.7moles
* one mole of a perfect gas occupies 22.414L under ideal conditions (pressure, temperature being standard - no big effect under human living area conditions; https://en.wikipedia.org/wiki/Molar_volume)
* 1kg of sublimated CO2 gas will therefore occupy 22.7x22.414=**508.8L**
* the density of dry ice is 1.4 to 1.6 (take 1.5; https://en.wikipedia.org/wiki/Dry_ice)
* 1kg of dry ice will therefore occupy 0.666L (1 [kg] / 1.5 [g/cm3])
* the sublimation of our kg of dry ice into gas will lead to a volume expansion of 762 times (nice!)

Just from the back of my memory (chemistry lessons are soooo long ago):

Molecular (weight) mass gives you the gramms one mole of the stuff weighs. Okay, that's technically totally wrong, confusing mass and weight, ignoring isotopes, pressure, temperature bla bla etc. etc., but good enough for house hold chemistry.

The molar mass of CO2 is about 44g/mol, so 44g of CO2 should give you 22.4l od gas under standard conditions.