For example, in this question.. A 11 L rigid container contains 10-kg of R134a at 100kPa. Determine the temperature and total enthalpy in the container. Why can we just assume that the temperature we're looking for is T_sat, how do we know this isn't a compressed liquid? How do we know it isn't a superheated vapor? The answer (-26.37) is found by looking it up in the saturated R134a table.