[jcmurtha]

Our hw assignment today is to answer the following questions. It's not a lot at all, but the problems are so confusing that I have no idea how to do them!  Any help would be greatly appreciated! 


NOTE: Standard Temperature and Pressure (abbreviated S.T.P.) means 760 mm Hg (or 1 atmosphere) at 0° C (or 273 K).


1. At a room temperature of 20° C, a silk petticoat is filled with 380 L of air at atmospheric pressure. To what volume will the petticoat expand if it fills with air heated by a fireplace to 52° C?

2. A chemist collects 5.2 L of oxygen gas (O2) at 28° C and a barometric pressure of 755 mm Hg. How many moles of oxygen did she collect?

3. The SpongeBob SquarePants balloon in the Macy's Thanksgiving Day Parade contains 16,200 cubic feet of helium. How many moles of helium is this, if the temperature on Thanksgiving day is 12° C and the barometric pressure is 752 mm Hg? One cubic foot = 28.317 L.

4. A chemist collects 2.1 g of Cl2 at 22° C and 755 mm Hg. (a) What volume of chlorine is this? (b) What would the volume be at S.T.P. (0° C, 760 mm Hg)?

5. A weather balloon is filled with 5.4 x 10^5 L of helium at a level barometric pressure of 762 mm Hg and a temperature of 16° C. It is then sent aloft to an altitude of about 10 km, where the temperature is -35° C and the air pressure is 472 mm Hg. (a) Find the volume of the balloon at this altitude and (b) find the mass of helium contained in the balloon.

[enahs]

PV=nRT