# Why does a NOx container get cold when NOx is released? and What is the relationship of the vapor pressure curve with the liquid-vapor dome?

The temperature at which $$\ce{NO_x}$$ is in equilibrium with its liquid and vapor phase at 1 atm is about –84 °C. Does that mean $$\ce{NO_x}$$ exists as a liquid at that temperature? What about it's vapor phase then, because it's vapor and liquid phase should be at equilibrium, right?

Also, it's that the reason why compressed $$\ce{NO_x}$$ when released from its closed and pressurized container (e.g. 50 bar) at 20 °C becomes a gas while its temperature drops? Therefore, the compressed $$\ce{NO_x}$$ was in it's liquid state at 50 bar, right?

If that's the case, then what is the relationship between the vapor pressure curve and the liquid-vapor dome? How would you use the saturated liquid-vapor tables to predict the vapor pressure for your substance? And which specific volume would you chose to define your substance: its liquid specific volume or its vapor specific volume?