PADI Divemaster Certification Practice Exam

What is the outcome when gas pressure is raised in contact with a liquid?

1. The gas goes into solution until reaching saturation

2. The gas expands and forms bubbles

3. The liquid evaporates rapidly

4. The gas remains unaffected by the pressure change

The correct answer is: The gas goes into solution until reaching saturation

When gas pressure is raised in contact with a liquid, the gas will dissolve into the liquid until it reaches saturation. This phenomenon is based on Henry’s Law, which states that the amount of gas that can dissolve in a liquid is directly proportional to the pressure of that gas above the liquid. As the pressure increases, more gas molecules are pushed into the liquid phase, allowing for greater solubility until the liquid cannot hold any more of that gas at the given pressure. This process is critical in various applications, including scuba diving, where understanding gas solubility is essential to prevent conditions like decompression sickness. It illustrates the relationship between pressure and gas behavior in liquid environments, demonstrating how changes in pressure can lead to changes in the concentration of dissolved gases. Although other options discuss gas behavior, they do not accurately represent the principle of gas solubility under increasing pressure, focusing instead on scenarios that don’t occur under these circumstances.