The pressure of Cl2 gas in a 2.0-L cylinder is 300 kPa at 25°C. What is the pressure (in kPa) when this gas is released into a 100-L chamber at 25°C?

Use the Ideal Gas Law: . Since the values of and are all constant in this problem, you know that the product of pressure times volume must be constant as well. Thus . You have values for and , so you can calculate .

If you know Boyle's Law, this would give you directly the formula:



which brings down to the same thing as what ebaines said. :)