aqua_regia - 29-4-2009 at 12:11
Why does Mentos react more violent with Coca Cola Light (also known as Diet Coca-Cola) than normal Coke?
Saber - 29-4-2009 at 12:21
Mentos react with Coke (generally) becuase it has a highly porous surface and that surace catalyses the breakdown of carbonic acid (carbonated water)
to CO2 and H2O.
In real life the decomposition should be the same between diet coke and normal coke. Maybe your coke had been open for a while or was older than the
diet coke?
Bikemaster - 29-4-2009 at 15:15
Not really sure of this, diet coca cola will react more violently that normal cola. I am not sure of why, but they have some difference into the mix.
Maybe it is the Aspartame than can help the reaction, because it is one of the main difference between those two type of cola.
Ozone - 29-4-2009 at 18:59
There is not enough aspartame in there to amount to much (even if it were to have any effect). My guess is that the diet drink has a significantly
lower viscosity (no sugar). Higher viscosities tend to stabilize dissolved gases in solution (MT limitation). And/or, perhaps, the sugar "fills" some
of the surface defects on the mento(s). I think that the pH is normalized between the two, if not, that is certainly a factor.
Cheers,
O3
PHILOU Zrealone - 10-5-2009 at 00:38
Following Henry's law of gas dissolution in liquids, the amount of dissolved salts or solutes expels the gas out of the solution!
Adding porrous solids also increases the number of nucleation sites (for nascent bubbles). This effect is used in distillation setups to get a
constant bubble flow out of the warmed liquid flask...you know the tiny stones
So in fact adding suggar, salt or fine sand to the cola will all end up in a gassing out; but suggar and salt will do it faster because they have two
processes (nucleation and dissolution); sand being unsoluble.
I guess that diet cola holding less solute will dissolve faster the mentos pills than normal coke, excess suggar being competitive towards dissolution
as Ozone suggested.