chem
posted by mel on .
A spherical glass container of unknown volume contains helium gas at 25°C and 1.950 atm. When a portion of the helium is withdrawn and adjusted to 1.00 atm at 23°C, it is found to have a volume of 1.55 cm3. The gas remaining in the first container shows a pressure of 1.710 atm. Calculate the volume of the spherical container.
in mL

Use PV = nRT to calculate n for the 1.55 cc removed.
Subtract P in the sphere of 1.950  that after 1.55 cc were removed (1.71) and use PV =nRT to calculate volume.
Post your work if you get stuck. 
am i using the 1 atm for pressure or the 1.950 atm for the first part?

for the first n i got .0638129 rounded... is that right?

do i need to change the cc into ml?
for the equation? 
The 638 part is right but the exponent is wrong. I suspect you used mL and not liters. Using PV = nRT,
P = 1 atm (that't the pressure of the 1.55 cc sample); V = 0.00155 Liters etc etc. I have 6.38 x 10^5 mols for n. Check my work.