Gas collection from electrolysis

[drsymes]

I am electrolysing a solution at the moment and want to measure the volume of hydrogen gas produced. My hydrogen sensor shows that hydrogen is being produced in sufficent quantities, but when I try to bubble this gas (via a plastic tube) through water and measure the volume in a measuring cylinder, no bubbles appear in the solution. Instead the solution in the tube surrounding the electrode is displaced by the gas. Can anyone tell me a way to overcome this? I've attached a diagram of my experimental setup.

 

[btrueblood]

Make the tube bigger, so that capillary forces become much smaller than gravity/buoyancy forces. I.e. make the tube several times larger in diameter than the largest observed bubble.

 

[drsymes]

By make the tube bigger, do you mean the diameter of the tube larger, or the length of tube itself longer?

 

[swall]

drsymes, he clearly wrote "make the tube several times larger in diameter".

 

[unclesyd]

What you need is a "Bubble-O-Meter" for your measurements. You can either buy one or a glass blower can make one in about 15 minutes.
Here is the picture of a single stage one and if applicable can easily be made in the lab or purchased.

http://www.bubble-o-meter.com/bom.php?curPos=BOM110ml

 

[btrueblood]

"the solution in the tube surrounding the electrode is displaced by the gas"

Bubbleometer is a good device, but won't help keep his electrode flooded.

 

[redpicker]

You need to make the distance that the mouth of the bubble tube is below the water less than the depth of the tube surrounding your electrode. You are displacing the electrolyte at the electrode becasue the pressure in the electrde tube is less than at the bubble tube. Your diagram is not exactly accurate, since the diagram shows the water level above the bubble tube to be less than the submerged portion of the electrode tube, when in reality, it must be greater.

Note that the specific gravity of the electrolyte will have an effect, but, generally, they electrlyte will be heavier than the water.

rp