In a recent physics class, I was told that for a gas enclosed in a closed vessel the pressure of the gas is variable but the volume and amount remains constant if we heat the gas. I understood this - simply as molecules can't escape out of closed vessel and still have same free space for moving.
Then I was told that if we consider gas in an open vessel and heat it, then its volume and pressure will be constant, then its molecules may escape, therefore the amount of gas cannot be constant on changing other conditions. Now I have the following doubts about this statement:
- Why will pressure remain constant if we heat the open container, as molecules will start moving more swiftly therefore will exert more pressure on walls.
- Why will volume be constant for the gas in open vessel, as volume is the free space available to gas for motion and in an open vessel whole universe is available to gas for motion.
Please elaborate on above points.