Bubbles!

[bumab]

Ha! It does seem hokey. They just (sometimes) make a little clover in the head with the last bit of beer to come out the tap...

 

Like this:

 

 

[Fishteacher73]

I just prefer just my moustache prints in the head of my pint. (I love my Guiness, but I actually prefer Murphy's Stout...The only problem is it is a bit trickier to get my hands on here in the states. Good thing I hve a good friend that works for a small distributor of imported beers.... You would be amazed at the "broken" cases he has to "throw away". Good thing I have a big trashcan...hehehehehe).

[Biochemist]

Ha! It does seem hokey. They just (sometimes) make a little clover in the head with the last bit of beer to come out the tap...

This is really not fair. It is only 11:15 AM here, and you are putting PICTURES of beer in your post. Gets my juices moving.

 

Then again, it is almost noon....

[bumab]

it's 6 o'clock somewhere! hahahha

[TeleMad]

cos CO2+H20 forms H2CO2 very unstable acid... more is like HCO2minus ...

 

Nitpick. CO2 + H2O forms carbonic acid, which is H2CO3. This then can decompose into an H+ and a bicarbonate ion, which is H2CO3-.

[sunofindia]

If there's any beer drinkers out there, you've probably noticed that tap beers can use two different gases for carbonation. Most use CO2, and some, notably Guinness, use N2. Lots of stouts are starting to use nitrogen as well.

 

Nitrogen gives smaller, more persistent bubbles. Why? I assume they last longer because they are smaller- less volume for the surface tension to hold in. But why are nitrogen bubbles smaller then carbon dioxide bubbles?

 

since the atoms in N2 are of same electronegatavity,the bonds are equi polar but in CO2, the atoms are diff. therefore there is electronegatavity diff. so the oxygen tries to pull atoms shared towards it, due to this may be they have larger size than N2 bubbles.

 

sun

[sunofindia]

Nitpick. CO2 + H2O forms carbonic acid, which is H2CO3. This then can decompose into an H+ and a bicarbonate ion, which is H2CO3-.

 

bicarbonate ion is HCO3- ITS NOT H2CO3-. i think it was a mistake in printing of telemad

 

sun

[Qfwfq]

Like this:

NOW I see what you mean. Anyway, to be a symbol of Eire it would have to be a shamrock, not a clover!

 

If you want to know the difference, you'd have to ask a botanist.

[Qfwfq]

Bright idea:

 

Sham"rock, n. [L. seamrog, seamar, trefoil, white

clover, white honeysuckle; akin to Gael. seamrag.] (Bot.)

A trifoliate plant used as a national emblem by the Irish.

The legend is that St. Patrick once plucked a leaf of it for

use in illustrating the doctrine of the trinity.

 

Note: The original plant was probably a kind of wood sorrel

({Oxalis Acetocella}); but now the name is given to the

white clover ({Trifolium repens}), and the black medic

({Medicago lupulina}).

[bumab]

So that's a clover because it has 4 leaves? Hmmm....

[Fishteacher73]

A shamrock is symbolic of Ireland because of the correlation to the trinity.

[TeleMad]

bicarbonate ion is HCO3- ITS NOT H2CO3-. i think it was a mistake in printing of telemad

 

sun

 

Yeah, my bad.

[TeleMad]

since the atoms in N2 are of same electronegatavity,the bonds are equi polar but in CO2, the atoms are diff. therefore there is electronegatavity diff. so the oxygen tries to pull atoms shared towards it, due to this may be they have larger size than N2 bubbles.

 

But the C is in between the two O's (O=C=O) and since the two oxygen's have the same electronegativity neither can 'pull' any harder on the C than the other, so their effects cancel each other out and the C remains equidistant between them.

 

I do agree that a CO2 molecule would be larger than an N2 molecule, but for other reasons: a CO2 molecule contains 3 atoms while an N2 molecule contains only 2 (and C, N, and O atoms all have about the same atomic radii), and the N2 molecule has a triple bond which reduces the bond length and so pulls the two N atoms even closer together. However, there are 'tons' of molecules in a single bubble so merely having a larger individual molecule size doesn't mean that the bubble would be larger too.

[Biochemist]

Yeah, my bad.

We should all recognize that Telemad almost never makes this sort of error. A testimony to his orientation to detail. Sonofindia should get creidt for noticing. It might be the last TM-error this year. ;)

[TeleMad]

We should all recognize that Telemad almost never makes this sort of error. A testimony to his orientation to detail. Sonofindia should get creidt for noticing. It might be the last TM-error this year. ;)

 

More importantly, we should all recognize that when someone actually shows something I wrote to be wrong, I admit it.

[Qfwfq]

Were it not for PV = nRT, what really would count would be volume of the density distribution + corrections for how well the shapes can pack together. The fact is that, around normal conditions, they don't pack at all. Not 'cause of the large number but 'cause it's a gas! Avogadro.

[Biochemist]

...The fact is that, around normal conditions, they don't pack at all. Not 'cause of the large number but 'cause it's a gas! Avogadro.

This is true. Polarity and molecule size (and H-bonding, in this case) may affect solubility, but it will probably not affect bubble size. Avogadro is in charge for gasses.

 

The only variables that I don't really understand are the surface tension specifics at the gas-liquid interface. The vast majority of the variation between N2 and CO2 bubble total volume difference is due to higher CO2 solubility. I assume this impacts individual bubble size as well, but the viscosity and surface tension of the liquid will probably impact bubble size, even for the same gas.

 

Notably some non-stout nitrogen-packed beers don't have near the head foam consistency that Guiness does. But the bubbles are still small.