A steel cylinder having a volume of 600. mL contains gaseous hydrogen iodide, HI, under pressure. HI is released from the cylinder into a balloon until no more HI comes out. Because of exposure to light, the HI in the baloon decomposes completely into gaseous hydrogen and solid iodine:
2HI(g)---> H2(g) + I2(s)
The final volume of the balloon is 1500 mL. The atmospheric pressure is 1.00 atm.
What was the original pressure of HI in the cylinder before the release of HI?