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Does tapping a Coke can stop it from fizzing up? Science has spoken

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We can't remember the first time someone told us that tapping the top of a coke can before opening it would stop it fizzing up or exploding, but we've never looked back since. We must have done it a million times - just in case, right?

But we've never, ever seen any actual evidence that it's true or has any logic behind it (that's not going to stop people voting for Trump either, we guess) - until now.

Christopher Arthur Edward Hamlett, a Chemistry lecturer at Nottingham Trent University believes that there could actually be something in the practice.

In an essay for The Conversation, he writes, ‘Before the can is opened, microscopic gas bubbles attach to the inside of it (nucleation). When the can is opened, these bubbles increase in size, due to the decrease in the solubility of CO2. When these bubbles reach a certain size they detach from the inside of the can and rise up to the top of the can due to buoyancy and displace liquid in their path.

"So what part could tapping the top of the can play in this process?... the bubbles in an unopened can nucleate at the walls, so tapping the can before opening could dislodge some of the bubbles, enabling them to float to the top of the liquid."

"When a can is opened, the bubbles expand with those deeper within the liquid travelling further than those near the surface, displacing more of the drink and possibly resulting in greater amounts of ejected liquid."

His conclusion? "A “tapped” can will have fewer of these “deep” bubbles and so less liquid will be dislodged – and possibly sprayed out – than an “untapped” can."

Of course, this is just theory - for true science it needs to be confirmed experimentally. Hoax site Snopes has tried it and claims that, if there is an effect from tapping, it's actually very small. Furthermore they say that a bigger effect is temperature - a chilled can will foam less than an unchilled one, while the best thing to do if you suspect an energetic can is simply to wait. 

In their wise words: "Time heals most things, especially when one of those things is delinquent carbonation just itching to have at you."

(Images: Rex/The Conversation)

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