Q.What is absolute zero?

[!TLDR] Absolute zero is the theoretical temperature (-273.15 °C = 0 K) at which an ideal gas's pressure/volume would extrapolate to zero. [!ANSWER] Absolute zero = -273.15 °C = …

As explained in §7.4.1, experiments show that pressure-versus-temperature and volume-versus-temperature graphs for gases (at constant volume or constant pressure respectively) are straight lines when temperature is measured in °C, but with a non-zero intercept -- they do not pass through the graph's origin. If these straight lines are extrapolated backwards (assuming, unrealistically, that the gas never liquefies), every gas's line -- regardless of its particular slope -- crosses the temperature axis (reaching zero pressure, or zero volume) at exactly the same point, $-273.15\,°\text{C}$. This universal, gas-independent temperature is called absolute zero. It is the theoretical lower limit of temperature, and it defines the zero of the Kelvin (absolute) s …

Explain absolute zero as the common temperature-axis intercept obtained by extrapolating the (linear, in ° …

Describing absolute zero as a temperature that has actually been reached experimentally, rather than a …