Sciencemadness Discussion Board

Bubbling HCl gas into water - bubbles not absorbing

RogueRose - 12-6-2016 at 13:14

Is there a good method to get the HCl gas to dissolve into the water in my graduated cylinder? I took a plastic tube and put lead weights in the bottom & covered with glue. Just above the weights are 4 holes (1/64" in size) drilled 90 degrees apart (around the tube) and the tube has a hose barb.

From the boiling flask I used a stopper with a hose barb. I attached the hose to the plastic tube and submerged the tube in 200ml of DH2O. I had 200ml of muriatic acid in the flask and put it on a hot plate on low (110-120 deg F).

When the bubbles come out, they just travel up the cylinder and escape. I thought they would be absorbed.

Is there anything that can be done to help the gas bubbles absorb into the water?

gradcyl.jpg - 188kB

DJF90 - 12-6-2016 at 13:24

Thats not HCl gas that you've got, but air that has expanded from the heated flask

blogfast25 - 12-6-2016 at 13:33

Chances are that once that air has been expelled, you won't even see any more bubbles: HCl absorption is that fast.

[Edited on 12-6-2016 by blogfast25]

aga - 12-6-2016 at 13:39

As per bloggers, once the Air has been flushed out, the HCl will ram into the water faster than a bulldozer chasing a cowdozer, giving no bubbles at all.

You should see a bubble at the end of the pipe, yet never escape to reach the surface.

Ammonia gas behaves similarly.

blogfast25 - 12-6-2016 at 15:36

Quote: Originally posted by aga  
As per bloggers, once the Air has been flushed out, the HCl will ram into the water faster than a bulldozer chasing a cowdozer, giving no bubbles at all.

You should see a bubble at the end of the pipe, yet never escape to reach the surface.

Ammonia gas behaves similarly.



Could be an interesting case for the Diffusion Equation (next up in calculus), when I think about it... (light bulb emoticon)

RogueRose - 13-6-2016 at 21:00

Thanks for the replies. I added some litmus paper to cover the top of the cylinder and there was no change in color and I then smelled some air coming of the top of the cylinder and it had no smell.

Now my next problem is I had TOTAL suck-back that was almost instantaneous (through 4 1/64" holes!!!) and the DH2O ended up back in the boiling flask. So I have to figure out how to deal with this suck-back issue.

Volanschemia - 13-6-2016 at 21:11

A suckback trap would work well...

Lead your gas tube into an empty sealed flask (or a jam jar) and lead another tube out of the flask and into your solution.

When suckback occurs the liquid will be sucked into the clean flask and none will end up in the reaction flask, provided the container is big enough.

ave369 - 13-6-2016 at 22:09

http://www.sciencemadness.org/smwiki/index.php/Funnel-and-be...

Volanschemia - 13-6-2016 at 22:20

That's a good trick too. It doesn't really work though if you're bubbling the gas into a grad cylinder.

It all depends on what your receiver is.