# Why do styrofoam cups fizz more than plastic cups? **URL:** \ **Category:** Factual Questions\ **Created:** [July 1, 2003, 3:52pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596 "2003-07-01T15:52:06Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![utomg](https://avatars.discourse-cdn.com/v4/letter/u/7bcc69/32.png) [@utomg](https://boards.straightdope.com/u/utomg)\ **Post date:** [July 1, 2003, 3:52pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/1 "2003-07-01T15:52:06Z")
If you open a fresh bottle of soda pop and pour it slowly into a plastic cup it fizzes (effervesces) a little bit. If you pour it slowly into a styrofoam cup it fizzes a lot — a whole lot! Why? Is it because styrofoam isn’t smooth, so when the soda is poured in the CO2 is “shaken” loose against the rough edges? Just wondering utomg ---
**Author:** ![Ivar](https://avatars.discourse-cdn.com/v4/letter/i/51bf81/32.png) [@Ivar](https://boards.straightdope.com/u/Ivar)\ **Post date:** [July 1, 2003, 3:56pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/2 "2003-07-01T15:56:50Z")
That’s a pretty crude but correct way to describe it. I’m sure someone will come along with a better explanation. ---
**Author:** ![Number](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/number/32/242_2.png) [@Number](https://boards.straightdope.com/u/Number)\ **Post date:** [July 1, 2003, 5:08pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/3 "2003-07-01T17:08:20Z")
Yep, the rough spots are called [nucleation sites](http://www.straightdope.com/classics/a3_356b.html). ---
**Author:** ![vertigo](https://avatars.discourse-cdn.com/v4/letter/v/3ec8ea/32.png) [@vertigo](https://boards.straightdope.com/u/vertigo)\ **Post date:** [July 1, 2003, 5:17pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/4 "2003-07-01T17:17:04Z")
I’m almost positive that is the reason. All the nooks and crannies in the styrofoam allow the CO2 a place to seed and then develop into bubbles big enough to break free and float to the surface and the cycle starts again. In related way you can cause some serious burns by microwaving a cup or bowl of water in a very smooth container. Without any imperfections to seed the steam bubbles, the water can reach boiling without actually coming to a “boil”. When moved or when a spoon is drop in it can explosively react and begin to boil. It can throw scalding water all over the place. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 1, 2003, 5:24pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/5 "2003-07-01T17:24:37Z")
On a related note, why does diet soda fizz out fast and go flat faster? Mild Hijack. ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 5:35pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/6 "2003-07-01T17:35:51Z")
Just curious Philster, but have you actually timed this out or is it subjective? It may have something to o with the chemical make up, the sugars in a “standard” soda being more likely to retain the CO2 in solution. It might be that the diet, has a lower boiling point. (I know I know, arguably the same thing, but not quite, one has to do with activity, the other entropy) This is what I suggest: 1. Take your normal diet and nondiet sodas and look at the labels. 2. Compare ingredients. 3. Compare Nutrition facts (this can tell you about the make up of the soda, not very precisely but if you see that they have the same ingredients, but that the sugar in the nondiet soda is 10g more than the diet, that is an explanation) 4. Freeze them measuring the temperatures at which they become solid. 5. Boil them, see which boils first and at which temperature. The one that boils first from your statement above should be the diet. 6. Add a twist of lemon and maybe a shot of rum to the boiled Dr Pepper and enjoy. Oh wait, that is just my prefered hot drink… But that should help you with out starting down the chemical activities, entropies, and what not. FYI, I am a chem/bio engineer so if you want to we can go into it, but I am lazy and the explanations from the experiment would work more easily. ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 5:37pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/7 "2003-07-01T17:37:29Z")
As you can see, I obviously spent too much time in the loabs and never took English courses. ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 5:40pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/8 "2003-07-01T17:40:53Z")
“Me fail english!!! Thats unpossible!!!” - Ralph ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 1, 2003, 6:39pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/9 "2003-07-01T18:39:13Z")
psi724, as a fellow Philly Doper, you have to trust me. Actually, diet soda goes flat faster, and I’ve timed it and measured the amount of bubbles after 1 minute. I mean, it’s so obvious (the difference in bubbles) that my anecdotal evidence will have to suffice. As you pour diet soda, regardless of brand, much of the carbonation is lost right after/during pouring. I avoid diet soda in 2 litre bottles because it doesn’t have a chance of surviving the pouring process. I buy cans or small bottles only. I guess it’s time to boil them… ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 6:51pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/10 "2003-07-01T18:51:21Z")
Interestingly enough from Coca-Cola… “We do not monitor the exact freezing temperatures of each of our products. However, our diet products freeze at a temperature similar to water, 32 degrees. Coca-Cola classic freezes at a slightly lower temperature, about 30 degrees. The pressure in an unopened bottle or can will cause the freezing point to be even lower. All diet beverages will freeze before their sugar counterparts. Sugars lower the freezing point of liquids. This means that the temperature must get lower than the normal freezing point of water before it freezes.” This would imply that the classic should boil at a lower temp than the diet. Although, the sugar percentage may get in the way with that. So now we are back to the question of activity and what VanderWaals and Hydrogen Bonding may be taking place. Course it could just be a matter of solubility. Be back on that one. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 1, 2003, 6:58pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/11 "2003-07-01T18:58:29Z")
Don’t some 'additives" to water DECREASE the freezing point while SIMULTANEOUSLY RAISING the boiling temp? Antifreeze additives do both. In the soda case, sugar would be the additive…it lowers the freezing temp and raises the boiling temp… Doesn’t salt do the same? Adding salt raises the boiling temperature, no? It lowers the freezing temp, we know that. I understood salt to raise the TEMP at which water boils. So, sugary soda will freeze at a lower temp and boil at a higher one…?? ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 7:11pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/12 "2003-07-01T19:11:26Z")
I wonder (since I have no diet soda around me) if it has to do with the ingredients being phosphoric acid in classic and X and phosphoric in diet? I have no diet here but I am guessing that there is another acidic ingredient to help disolve the other stuff that is put in. The following reactions take place with water & Co2: CO2 (aq) + H2O H2CO3 (aq) H2CO3 (aq) + H2O H3O+ (aq) + HCO3- (aq) HCO3- (aq) + H2O H3O+ (aq) + CO32- (aq) Normally, since the CO2 is coming out, the reactions naturally drift towards the CO2, and thus it comes out. Seems to me that if there are too many donators of H to the place that it would drive the reactions towards CO2, thus more likely to “boil” completly out faster than standard. I am looking for data on solubility, but with out calculations I think it is hopeless. And like I already said, I am lazy today. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 1, 2003, 7:13pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/13 "2003-07-01T19:13:47Z")
Aha…I just learned that any non-volatile soluble substance - like sugar - will raise the boiling point. So, to help myslef, siince artificial sweeteners are ‘sweeter’ than sugar, by volume there is less sweetener in diet than regular soda, thereby causing regular sugary soda to have a higher boiling point because it has more soluble substance than diet. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 1, 2003, 7:16pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/14 "2003-07-01T19:16:10Z")
But now I am confused because more sweetener should mean moe nucleation points??? AHH! (Thanks psi, for your crack at it…but I’m confused!) ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 7:32pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/15 "2003-07-01T19:32:23Z")
I think that the salt thing you raised is not right. The salt raises the entropy: dG=dH-TdS No chemical reactions therefor dG=0 dH=TdS At phase changes dH=H1-H2 = C C=TdS dS = Cpln(T2/T1) dS = (Cp1 + Cp2 + …) ln (T2/T1) Since Cp(water) + Cp(anything) \> Cp(water) dS must increase. If H = TdS and dS increases, then T must decrease. Think about it this way, you put salt into water to make it easier to boi or to melt the icel, same thing as oil (depending on the type it will just break surface tension). There is not too much change but enough that it helps. To get it hotter, you cover it with the lid, thus increasing pressure, i.e. the pressure cooker. As for the antifreeze, I think that the system is under pressure that does the trick, not that the antifreeze raises the boiling temp. Unless the additive has a higher boiling point than the water… ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 7:40pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/16 "2003-07-01T19:40:40Z")
I realize that the formula dS = CPln(t2/T1) is a change in temp, and that at steady state (no dT) there is no change in dS but the principle still applies. Also, the sweeteners are typically more swet than sugar, thus lee sweetener creating less nucleation sites. There for lower boiling point. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 1, 2003, 8:08pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/17 "2003-07-01T20:08:16Z")
So why does diet soda go flat real fast? My head hurts. ---
**Author:** ![psi724](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@psi724](https://boards.straightdope.com/u/psi724)\ **Post date:** [July 1, 2003, 8:22pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/18 "2003-07-01T20:22:37Z")
Has to do with my explanation on CO2 reactions above. Summary: 1. Established that diet will boil at a LOWER temp. Thus less soluble with CO2 than nondiet. At boiliing temp for diet, nondiet will be still retaining CO2 whereas it will be boing off in the diet. 2. Possible more acid in diet sodas, thus causing more of a swing to CO2 in the reactions. More CO2 present, more that will come out. 3. Less possible activity and Hydrogen bonding etc between the CO2 with the sweetening agent in diet than with sugar in nondiet. Thus more readily comes out in diet than non diet. 4. Boiled Dr. Pepper and lemon go good together. Other than these, I would say that it is a factor of the coefficients of heat. Just guessing here, but diet might heat up faster than nondiet, thus releasing more CO2. Check that by timing the temperature rise between the 2 drinks. And I was just determined to be a dork by my office for wondering and researching this. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [July 1, 2003, 9:04pm UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/19 "2003-07-01T21:04:55Z")
> [@](#): > > \*Originally posted by psi724 \* > \*\*I realize that the formula dS = CPln(t2/T1) is a change in temp, and that at steady state (no dT) there is no change in dS but the principle still applies. > > Also, the sweeteners are typically more swet than sugar, thus lee sweetener creating less nucleation sites. There for lower boiling point. \*\* Well, nucleation sites aren’t molecular-sized phenomena (i don’t remember if they are large microscopic phenomena or just tiny macroscopic, but larger than molecular-sized.) ---
**Author:** ![bbeaty](https://avatars.discourse-cdn.com/v4/letter/b/c0e974/32.png) [@bbeaty](https://boards.straightdope.com/u/bbeaty)\ **Post date:** [July 2, 2003, 3:57am UTC](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596/20 "2003-07-02T03:57:23Z")
Nucleation sites are called… BUBBLES. Carbon dioxide needs a gas/liquid interface if it’s to come out of solution. If there aren’t any tiny pre-existing bubbles, there will be no large bubbles. If you pour some cola into a styrofoam cup, the crevices provide trapped bubbles which grow and then break off, leaving a tiny bubble to repeat the process. Stare into your beer. Those little spots which emit strings of bubbles are either air-filled scratches, or they are bits of air-filled filth which the dishwasher missed. Good sources of large numbers of tiny bubbles: dry sugar, salt, powdered creamer or choclate. Melted ice cream. Dry, frosty ice cubes. Diluted (liquified) whipped cream. Water which has just had some dry powder added recently. Hot tap water (full of microbubbles.) If you (sneakily) place any of the above materials into a glass and then let someone pour in a carbonated beverage, guess what happens? Or: prepare two nearly-full glasses of root beer. Into one dump some milk. It turns beige, but that’s all. Into the other pour some whipped cream which has been mixed with water to make it resemble milk. DOOSH! With an appropriate orifce attached to the root beer glass, you could make a rocket engine. Ah, try using a turkey baster to rapidly inject a large volume of dilute whipcream into a nearly-full 2L bottle of warm cola. 🙂 PS If you have a mouthful of melted ice cream and then take a big swig of warm rootbeer, don’t try to keep your mouth closed or the foam explosion will jet out of your nose. FOLLOW THESE INSTRUCTIONS (See ‘foam blast’) [http://amasci.com/brain/](http://amasci.com/brain/) [Next page](https://boards.straightdope.com/t/why-do-styrofoam-cups-fizz-more-than-plastic-cups/185596.md?page=2)