Heterogeneous nucleation - Mentos and coke

[Kruler]

Hello guys , I'm a medical student , and I'm very fascinated by this Mentos and diet cola experiment , however i do not understand it completely and i would like to know the followings
-From my understanding it happens because of Heterogeneous Nucleation , is that right ? Then i do not undertand why is the CO2, which starts as liquid form turns actually into gas ? isn't supposed to turn into solid by common logic ? I don't really understand that.
-Why is that happens mainly when the mentos sinks at the bottom of the coke ?
-After this phenomenon, is the liquid (coke) + CO2 still pressurized ? if its not , why is it losing it's pressure ?
-Last question about the pressure - does a super-pressurized coke will produce an higher eruption ?

I read some in the internet , but every website explains the Nucleation process differently , i think i understand it , but not fully though.

I asked a lot of questions , but I'm really curious :)

 

[CWatters]

Then i do not undertand why is the CO2, which starts as liquid form turns actually into gas ? isn't supposed to turn into solid by common logic ?

The C02 starts off as a gas disolved in the coke. It stays a gas.

 

[Kruler]

The C02 starts off as a gas disolved in the coke. It stays a gas.

Thanks for the reply , so i assume that the cola + CO2 is a supersaturated solution , why is the mentos and the nucleation causing it to lose pressure ?

 

[Kruler]

sry for bumping guys , i would really appreciate if anyone knows a good webpage / article / book about nucleation (except wiki)

 

[pmacias]

Hello there! I am happy to provide some answers to your questions about heterogeneous nucleation and the Mentos and coke experiment.

Firstly, you are correct in your understanding that the Mentos and coke experiment is a result of heterogeneous nucleation. This is a process where gas molecules (in this case, carbon dioxide) are able to form bubbles more easily on a surface (the rough surface of the Mentos candy) than in the surrounding liquid. This leads to a rapid release of gas, resulting in the fizzy eruption we see in the experiment.

Now, to address your question about why the CO2 turns into gas instead of solid. When the Mentos candy is dropped into the coke, it causes a sudden increase in the surface area of the liquid. This leads to a decrease in pressure, which causes the dissolved carbon dioxide gas to come out of solution and form bubbles. The gas molecules then expand and rise to the surface, creating the foamy eruption we see.

As for why this happens mainly when the Mentos sinks to the bottom of the coke, it is because the bottom of the bottle has a higher concentration of dissolved carbon dioxide due to the pressure from the gas in the bottle. This means that there are more gas molecules available to form bubbles when the Mentos is dropped in.

After the eruption, the liquid (coke) and CO2 are still pressurized. However, some of the gas has been released in the eruption, leading to a decrease in pressure. This is why the bottle may not feel as hard or pressurized after the experiment.

Lastly, regarding your question about whether a super-pressurized coke will produce a higher eruption, the answer is yes. The more dissolved carbon dioxide in the liquid, the more gas molecules available to form bubbles and create a larger eruption.

I hope this helps to answer your questions and increase your understanding of heterogeneous nucleation and the Mentos and coke experiment. Keep asking questions and exploring the world around you!