Sometimes the problem will give the initial and final states in different units. In this case, you need to identify all of the pressures and all of the volumes by organizing them into a table (step 1 of our problem-solving method). Then, you need to convert all of your pressures to the same units (usually atmospheres works best) and all of your volumes to the same units (usually liters). Then you can set up the problem and solve. A balloon filled with 2.00 L of helium initially at 1.85 atm of pressure rises into the atmosphere. When the surrounding pressure reaches 340. mmHg, the balloon will burst. If 1 atm = 760. mmHg, what volume will the balloon occupy in the instant before it bursts?