chem
posted by mel .
A piece of solid carbon dioxide, with a mass of 6.2 g, is placed in a 4.0 L otherwise empty container at 21°C.
(
a) What is the pressure in the container after all the carbon dioxide vaporizes?
atm (.86 atm)
(b) If 6.2 g solid carbon dioxide were placed in the same container but it already contained air at 740 torr, what would be the partial pressure of carbon dioxide?
in atm
(c) What would be the total pressure in the container after the carbon dioxide vaporizes?
in atm

a) I found 0.86 atm
b)I'm assuming the CO2 vaporizes completely. Won't the partial pressure of the CO2 be the same as in (a)? Dalton's Law tells us that the total pressure is the sum of the partial pressures of each gas and each gas will exert a pressure as if the other gas were not present. Check my thinking. OR, try PV = nRT to calculate pCO2 (done in part a), then calcualte pressure of air (740/760) and add them together. Then determine mols CO2 and mols air, add them together and use PV = nRT to calculate total pressure. That should be the same total as you obtained when you added the partial pressure of each.
c)explained in (b) 
yugioh!!!!!