Admission Test for Dental Hygiene (ATDH) Practice

What would happen to gas pressure if the volume is increased at constant temperature?

1. Pressure increases.

2. Pressure decreases.

3. Pressure remains constant.

4. Pressure becomes unpredictable.

The correct answer is: Pressure decreases.

The correct answer relates to Boyle's Law, which states that for a given mass of an ideal gas at constant temperature, the pressure is inversely proportional to its volume. This means that if the volume of the gas is increased while keeping the temperature constant, the gas molecules have more space to move around. As a result, they collide with the walls of the container less frequently, leading to a decrease in pressure. In simpler terms, think of a balloon. When you inflate it (increasing its volume), the pressure inside the balloon decreases relative to the pressure of the air outside because the gas molecules in the balloon are spread further apart and hitting the sides of the balloon less often. This principle underlines why an increase in volume results in a decrease in pressure, confirming that at a constant temperature, the relationship between volume and pressure is such that an increase in one causes a decrease in the other. Thus, when considering the behavior of gases under these conditions, it is essential to understand that increasing volume directly results in decreased pressure.