Calculate the density.

Question

(a) Calculate the density of SO₂ gas in g/L at 715 mm Hg and 68°C. 

(b) Calculate the density of N₂O gas in g/L at 1.23 atm and 28°C

Answer 1

But since you asked,

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For (a), determine the molar mass of SO₂ -- use a Periodic Table for element masses.

That amount of gas (1 mole) would occupy 22.4 L (the standard molar volume) at STP conditions (O C, 1 atm=760 mm Hg).

So the fastest way to a solution would be to take the density of the gas at STP (1 molar mass/22.4 L) and multiply by correction factors for the pressure and temperature: (715/760) and (273.15)/(273.15+68.0) respectively. -- Remember, temperature are always calculated through in terms of K, since an ideal gas has volume directly proportional to absolute temperature. How do you remember which thing goes in the numerators vs. the denominators? You think about it! Less pressure = less density (the gas expands); higher temperature = less density (the gas expands).

The rest of this assignment appears to be practice at converting masses to moles and back. You use molar mass for each species, which you either calculate ab initio or look up perhaps in a CRC Handbook. Better for you if you calculate, since that's probably what you'll have to do on a test eventually?

-- Cheers, --Mr. d.