Charles' Law: Heating a gas at constant pressure

An experiment to demonstrate Charles' Law - the behaviour of a gas when heated at constant pressure.
The experiment features a glass capillary tube that is sealed at one end and has a mercury thread at the other, which is able to move along the tube when the gas expands.
The tube is heated in a water bath: A scale allows the volume of the gas to be measured and a thermometer shows the temperature in celsius.
Apologies for the shaky camera work. The video was taken in time lapse (actual time for the experiment was around 30 minutes) and it was necessary to move the camera to give clear shots of the mercury thread and thermometer.
Some of you may want to think about two sources of error: Parallax and the fact that some of the gas column sticks out above the water line. Despite these sources of error, I found that the data from the experiment have a pretty good measurement of absolute zero.

[@subham2593]

Sir please don't stop making such a help full videos

[@pesgamerpro4652]

Can u plz answer how had the pressure determined?

[@QuantumBoffin]

The pressure of the gas is just equal to atmospheric pressure, as the other side of the mercury thread is open to the atmosphere.

[@gardening_vibes]

@@QuantumBoffin But since the burner is on, wouldn't it change the atmospheric pressure?

[@QuantumBoffin]

The atmosphere is a big thing... it would take a lot lot more than one little burner to affect the pressure. Atmospheric pressure is caused by the weight of the atmosphere pushing down on things.

[@vijayanand8077]

Well done✌

[@susilachyne83]

I still can't understand.. Please explain

[@QuantumBoffin]

When gases are heated they expand, becoming less dense. This is the reason why hot air balloons float: Because the hot air in the balloon is less dense than the surrounding air. This experiment just allows precise measurements of that expansion to be measured.