Because the chemicals are different
pV = nRT
p = nRT/V
p= 1 x 0.08205 x 1000/ 2
p = 41.025 Pa
Edit: The unit should be atm instead of Pa, as pointed out by a nice human being.
The percent composition<span> gives you only the empirical formula.
</span><span>To get the molecular formula, you must either know the molecular mass or do an experiment to find it.</span>
A. 0.25 g/mL
Because 6/24 is 0.25
The problem you have written you almost have it solved. Take the moles that you have calculated and multiply that by the molecular weight to get the grams.
The STP problem:
use the moles you calculated along with 1 atm for Pressure, and 273 for the temperature and plug into the PV = nRT equation. (also use 0.0821 for R)
From there you can solve for the volume
Hope this helps!
