Mentos-Cola: a short explanation of physical reaction



High definition pdf here

we know well about the giant eruption of carbon dioxide in diet cola-mentos mix and also it is a physical reaction. But we must know what causes the diet cola to liberate carbon dioxide in short period.

Proof for the physical reaction1 (not acid-base reaction):

There was a myth that an explosive acid-base reaction taking place when we mixup diet cola and mentos, but it has been disproved as following; Usually we can observe the changes in pH value if it’s a acid-base reaction. Diet cola has the pH of 3.0 and this value didn’t change after the addition of Mentos, which means clearly it’s a not acid-base reaction. But if you add baking soda into the diet cola then the pH values increases to 6.1.

Potassium benzoate, Aspartame and Gum Arabic:
Mythbusters1 and Tonya Shea Coffey2 described that the presence of gum arabic (a surfactant) in Mentos, and potassium benzoate (a preservative), aspartame (a sweetener of food and most common in beverages) in diet cola causes the eruption of carbon dioxide. The detailed investigation gives an idea that when we drop a Mentos into the diet cola container it reaches the bottom and the surfactant “gum arabic” which reduces the surface tension of water (water resists the expansion tiny carbon dioxide bubbles by means of forming strong attraction between water molecule and the tiny bubbles require more energy to push water molecule away from each other for the purpose of expansion; this phenomenon called “surface tension”; ultimately the dissolved tiny carbon dioxide bubbles around the Mentos escapes, these liberated bubbles from the bottom of the container will act as an growth site, which will help the remaining dissolved carbon dioxide to over the surface tension of water and causes the giant eruption of gas.

There’s an further explanation for the origin of fizz:
Cola already has carbonic acid (potassium benzoate will be the form of benzoic acid at lower pH) and carbon dioxide in the a certain equilibrium which gets disturbed upon the addition of Mentos.

Google video:

video 1, video 2

References:
1. Adam Savage and Jamie Hyneman. “Episode 57: Mentos and Soda.” Mythbusters, Discovery Channel, first aired August 9, 2006.

2. Tonya Shea Coffey, “Diet Coke and Mentos: What is really behind this physical reaction?,” American Journal of Physics 76, no. 6 (June 0, 2008): 551-557, doi:10.1119/1.2888546.

Weblinks:

Link 1, Link 2, Link 3, Link 4

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Onion tears

onion5.jpg

High definition pdf here

It’s well known that onion is one of the highly potential healthy flavoring food, since it gives us few phytochemicals, nutrients, etc. for eg; one of the major constituent is Quercetin, which is an anti-inflamatory as well as antioxidant.

But, why it irritates our eyes while slicing them? here comes the reason

When we slice the onion, cells get break down which releases the enzyme called “Alliinase” (look at the picture) and it converts the more abundant sulphoxide of onion (a aminoacid called “1-propenyl L-cysteine sulphoxide”) into sulphenic acid (1-propenylsuphenicacid), which is unstable (never isolated) and it ultimately rearranges to the more volatile Propanthial s-oxide. Since this s-oxide is more volatile it can easily spread over the air and it reaches our eyes, where it reacts with water and converted into diluted sulphuricacid, this acid stains our never system and triggers the tear glands to produce tear for the purpose of diluting this sulphuric acid.

Some tips to reduce your tear while chopping onions,

1. Usually root of the onion releases maximum amount of sulfuric compounds, so it’s better to cut the stem (top) of onion and peel downwards to the root, chop it without cutting off the root until the last.

2. Cooling in refrigerator (enzyme will be less active) or washing the peeled onion in water or slicing under water flow also suppress the s-oxide to reach our eyes.

3. Chopping near to the flame (for eg; near to gar burner) also helps.

4. Use sharp knife for slicing, which could reduces the amount broken cells.

Reference:
1. Imai, S.; Tsuge, N.; Tomotake, M.; Nagatome, Y.; Sawada, H.; Nagata, T.; Kumagai, H., Plant biochemistry: An onion enzyme that makes the eyes water. Nature 2002, 419, (6908), 685 doi:10.1038/419685a.

Cat like mammal “Meerkat”

Let me share with you about a mammal called “Meerkat” and will give you a short description.

Meerkat.jpg

Not only the name looks like “cat” it also looking like (having sharp claw), but they can stand with rear 2 legs (as you can see in the picture) and the thin lengthy tail and body structure helps to balance. They mostly inhabits in the Desert of South Africa. The most important thing which I like is they are “Altruistic”; it means “selfless”, for eg; if there is a threat while they forage then the senior Meerkats usually endanger of their own live for the young Meerkat. Also it’s interesting to know that there will be always one or more sentry while foraging and these sentries bark when there is a predator which will continue until there’s no threat of fear, later on different bark will emerge all hidden Meerkats from the burrow.

Hide unhide your files (Mac OSX tip)

you can’t do this from finder. it has to be done from terminal.

To unhide: chflags hidden (path of file or folder)

To unhide: chflags nohidden (path of file or folder)

replace (path of file or folder) with unix path of your file or folder. The easiest way to do this is to drag the file or folder to the terminal window.

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To view the hidden file or folder

go to finder: press Shift+command+G together (make sure you are in the same directory where hidden file or folder located), it pops a window, give the name of hidden file or folder, that’s it now you can see it.

To view the hidden file or folder from any location

press Shift+command+G together, give the name of hidden file or folder with full path (eg: /Users/xxxxx/Desktop/music.txt).