How will the boiling point of a substance be affected by increasing the atmospheric pressure?
How will the boiling point of a substance be affected by decreasing the atmospheric pressure?
Increasing pressure increases boiling point; decreasing pressure decreases boiling point.
To understand how the boiling point of a substance is affected by changes in atmospheric pressure, we need to review the concept of boiling.
Boiling is the process in which a substance changes from its liquid state to its gaseous state by the formation of bubbles within the liquid. This transformation occurs when the substance's vapor pressure equals or exceeds the external pressure applied on it, typically atmospheric pressure.
Now, let's consider the two scenarios you mentioned:
1. Increasing atmospheric pressure: When the atmospheric pressure increases, the boiling point of a substance also increases. This is because the higher external pressure makes it more difficult for the substance's vapor pressure to equal or exceed the atmospheric pressure. Consequently, the substance needs to be heated to a higher temperature to generate enough vapor pressure for boiling to occur.
2. Decreasing atmospheric pressure: Conversely, when the atmospheric pressure decreases, the boiling point of a substance decreases as well. With reduced external pressure, it becomes easier for the substance's vapor pressure to reach the threshold required for boiling. Therefore, the substance will boil at a lower temperature compared to when the atmospheric pressure is higher.
To summarize, an increase in atmospheric pressure raises the boiling point of a substance, while a decrease in atmospheric pressure lowers the boiling point.