Definition: An isochem is a system in which energy flows from the source to the sink. In an idealized context, this can be represented by a closed loop where each point of the system has a temperature, pressure, or other property that can change as it moves through the loop. In everyday language, an isochem might refer to a system where all the heat is transferred from one body to another at constant temperatures and pressures. This would typically involve heat transfer through conduction, radiation, or con