Please specify the context you are referring to. Light gas may be referred to as a component with high relative volatility.

Phase split is the separation of two phases, for example splitting the vapour and liquid phases in flash separator.

Regards,

Rahul Jain

I am following a recommendation by J. D. Seader for selection of a thermodynamic property package. Here is the link for the decision tree: http://imgur.com/a/lsYdY

Thanks