Solid iodine has a vapor pressure of 1.0 mmHg at 39°C. How many moles of iodine will sublime into a 500. mL flask at this temperature? If the volume of the flask is doubled at constant temperature, what will happen to the equilibrium vapor pressure of I2? (Assume some solid I2 is always present in the container.)
PV = nRT, so n = PV/RT
n = (1 mm Hg)*(500 mL) / (760 mm Hg/atm)*(1000 mL/L)*(0.082 L·atm/K·mol)*(312.15 K)
= 2.57*10^-5 moles.
on changing volume of flask doesnt change the vapour pressure of the flask.