What are the general names for the fixed points? Why are they called fixed points?
I got the answer for the first question: the boiling point, the freezing point, and the triple point of a substance.
I just can't figure out the second question.
The term "fixed points" in thermodynamics refers to specific temperatures or states of a substance where certain physical or chemical properties remain constant under defined conditions. These fixed points serve as reference points in temperature measurement and calibration.
The fixed points are called "fixed" because they do not change regardless of any external factors or variations in the surroundings. For example, the boiling point of a substance is the temperature at which it changes from a liquid to a gas under standard atmospheric pressure. No matter the quantity of the substance or the presence of impurities, the boiling point remains constant.
Similarly, the freezing point is the temperature at which a substance changes from a liquid to a solid, and the triple point is the temperature and pressure at which the three phases (solid, liquid, and gas) of a substance coexist in equilibrium. These fixed points provide standardized and reproducible conditions for accurate temperature measurements and comparisons.
Therefore, the fixed points are named so because they represent specific temperatures where certain properties remain fixed or unchanged, hence the term "fixed points."