Liquids actually don't have two coefficients of expansion, they only have one! The confusion might arise from the different ways we describe how liquids expand:

* Volume Expansion: This refers to the change in volume of a liquid as its temperature changes. It's the most common way to express expansion for liquids and is represented by the volume expansion coefficient (β).

* Linear Expansion: This is typically used for solids, describing the change in length of a material in one direction. It's not usually applied to liquids because liquids don't have a fixed shape and don't expand in a defined linear direction.

Here's why we don't typically use linear expansion for liquids:

* No Fixed Shape: Liquids take the shape of their container, so defining a specific linear direction for expansion doesn't make sense.

* Random Molecular Motion: The molecules in a liquid move more freely than those in a solid. They're constantly jostling and colliding, leading to changes in volume rather than linear expansion in a specific direction.

Therefore, when discussing the expansion of liquids, we focus on the volume expansion coefficient (β), which quantifies the change in volume per degree Celsius (or Fahrenheit) change in temperature.