Why Does Less Foam Form in a Soda Cup?

  • Thread starter daniel_i_l
  • Start date
In summary, the amount of foam when filling a cup with soda for the second time is less due to the cup's surface being coated with soda, which prevents interaction between the soda and the cup, resulting in fewer bubbles being formed. Additionally, pouring into a wet glass or using a previously opened bottle can also affect the amount of foam. This is due to the wet surface providing less nucleation sites for bubbles to form, resulting in less foam.
  • #1
daniel_i_l
Gold Member
868
0
Why is there less foam the second time you fill a cup with soda than the first time.
At first I thought that it had to do with the temperture of the cup changing(it cools down after filling it the first time) but I get the same resault with warm coke or with a cold cup?
Any ideas?
Thanks.
 
Physics news on Phys.org
  • #2
There could be many "systematic errors." If you're pouring from the same bottle for both the first and second cups, it's possible that the way you're holding the bottle the second time (it is lighter and needs to be held at a different angle) is affecting the results.

You'd really need to start over with a totally fresh bottle of soda with each "run" of the experiment, to isolate the cup as the only variable.

- Warren
 
  • #3
daniel_i_l said:
Why is there less foam the second time you fill a cup with soda than the first time.
At first I thought that it had to do with the temperture of the cup changing(it cools down after filling it the first time) but I get the same resault with warm coke or with a cold cup?
Any ideas?
Thanks.
I think the foam is caused by dirt or dust on the surface of the cup.
I think there is less foam with a really clean glass.
When you refill the cup, there is a coating of soda on the surface, which probably keeps the new soda from interacting with the surface.
 
  • #4
If you're pouring from a bottle (as opposed to filling from a fountain), it's possibly just the soda in the bottle going flat (every time you open the bottle, the soda outgases some) with time of exposure and number of prior openings.
 
  • #5
Meir Achuz said:
I think the foam is caused by dirt or dust on the surface of the cup.
I think there is less foam with a really clean glass.
When you refill the cup, there is a coating of soda on the surface, which probably keeps the new soda from interacting with the surface.
Why would dirt cause foam? That doesn't make any sense.

The obvious answer is that when you first open the bottle of soda it's at its maximum carbonation level. It's also possible that the change in pressure when you first open it allows more bubbles to be released so if you pour it right away you get more foam. Once you let it sit for a bit, that initial level level of carbonation isn't there anymore so you don't get as much foam. (Which is pretty much what Gokul said)
 
  • #6
Pouring into a wet glass makes much less foam than pouring into a dry glass, regardless of the condition of the bottle. Try it by wetting the glass with water, and using a fresh bottle.


Not sure of why though. Something to do with nucleation of bubbles from the glass surface, purely as a guess.
 
  • #7
dav2008 said:
Why would dirt cause foam? That doesn't make any sense.
It makes perfect sense if you understand how bubbles are formed in liquids. Google or Wiki "nucleation sites"


Personally, I think that a cup that has previously had liquid in it has been "wetted" - all its nucleation sites are covered or blocked with a thin layer of liquid. Less available nucleation sites, less foam. [Edit: ... as I now see brewnog points out before me]
 
Last edited:
  • #8
DaveC426913 said:
It makes perfect sense if you understand how bubbles are formed in liquids. Google or Wiki "nucleation sites"


Personally, I think that a cup that has previously had liquid in it has been "wetted" - all its nucleation sites are covered or blocked with a thin layer of liquid. Less available nucleation sites, less foam. [Edit: ... as I now see brewnog points out before me]
Yeah I made that comment before thinking. I guess what I wanted to say was that the amount of dust in a glass wouldn't be enough to make that big of a difference.
 

1. Why does less foam form in a soda cup compared to other drinks?

Less foam forms in a soda cup because soda contains carbon dioxide gas, which is added during the bottling process. The gas is released when the soda is opened or poured, creating bubbles and foam. However, the amount of carbon dioxide in soda is much less than in other carbonated drinks, such as beer or champagne, resulting in less foam formation.

2. Can the temperature of the soda affect the amount of foam in the cup?

Yes, temperature can play a role in the amount of foam formed in a soda cup. When soda is served at a colder temperature, the carbon dioxide gas is able to dissolve better in the liquid, resulting in less foam. On the other hand, warmer temperatures can cause the carbon dioxide to escape more quickly, creating more foam.

3. Does the type of soda or brand affect the amount of foam in the cup?

Yes, the type and brand of soda can also affect the amount of foam formed in a cup. Some sodas may have a higher concentration of carbon dioxide, resulting in more foam, while others may have a lower concentration and therefore less foam. Additionally, different brands may use different bottling processes or amounts of carbon dioxide, leading to varying levels of foam formation.

4. Why do some people prefer more foam in their soda, while others prefer less?

The preference for foam in soda is subjective and varies from person to person. Some may enjoy the texture and visual appeal of foam, while others may find it unpleasant or prefer a smoother drinking experience. Additionally, the amount of foam may affect the taste of the soda, with some people preferring a more diluted taste while others prefer a stronger flavor.

5. Is there a way to control the amount of foam in a soda cup?

Yes, there are some factors that can be controlled to affect the amount of foam in a soda cup. These include the temperature of the soda, the amount of carbon dioxide in the soda, and the pouring technique. For example, pouring the soda slowly and at an angle can help reduce foam formation, while shaking the soda bottle beforehand can increase the amount of foam. However, the amount of foam may also vary based on the specific soda brand and type.

Similar threads

Why does a warm weighing cup weigh less?
    • Other Physics Topics
Replies
27
Views
4K
Can Soda Going Flat Affect Its Mass?
    • Other Physics Topics
Replies
25
Views
13K
B Everyday microwave oven physics: Does the energy transferred depend on what is inside?
    • Other Physics Topics
Replies
33
Views
2K
How do you even cheat in chess?
    • General Discussion
2
Replies
42
Views
3K
What is the mechanism behind milk foaming in cappuccinos?
    • Other Physics Topics
Replies
5
Views
4K
Why does foam form on orange squash?
    • Other Physics Topics
Replies
5
Views
9K
Can the Rapid Depressurization of a Soda Can Cause Significant Cooling?
    • Other Physics Topics
Replies
2
Views
2K
I Is the Continuum Limit of Spin Foam Dynamics Equivalent to Massless Gravitons?
    • Beyond the Standard Models
Replies
2
Views
2K
Trivial Question - rate of heat loss from hot drink
    • Thermodynamics
Replies
13
Views
1K
Are Conventional Turkey Thawing Instructions Backwards?
    • General Discussion
Replies
32
Views
2K

Hot Threads

Recent Insights

Back
Top