This condition for one substance defines the Kelvin temperature scale, and this condition sits at the intersection of two coexistence curves.
Systems with n phases possess n choose three of these, which are unique for single-component situations because of Gibbs's phase rule. The plot of two solutions to the Clausius-Clapeyron equation for a substance intersect here, while helium-4's superfluidity gives it two of these. This condition for one substance defines the Kelvin temperature scale, and this condition sits at the intersection of two coexistence curves. For 10 points, name these pairs of temperature and pressure conditions, which for water is 273.16 K and about six hundred twelve pascals, in which a substance exists as a solid, liquid, and gas simultaneously.
Systems with n phases possess n choose three of these, which are unique for single-component situations because of Gibbs's phase rule.
{triple} point