# CSTR vs. BSTR system open or closed

by Woopydalan
Tags: bstr, cstr
 P: 746 Hello, I was wondering, is it the case that a CSTR is an open system because there is flow passing in and out of the tank, thus passing the control volume, so it's open. Similarly for a BSTR, the fact that there is no flow means that it is closed? I mean in that sense, a beaker with a chemical reaction going inside of it is a BSTR right? Isn't that open to the environment, so why is it not considered an open system? Is the way that closed/open system is used for the tank reactors the same meaning as for the usual meaning of a closed or open system (i.e. nothing interacts with the system from the environment?)