Why is a can of fizzy drink so much fizzier if I shake it up first

A.� Your can of fizzy drink is carbonated, the carbon dioxide is under pressure in the can so that the gas dissolves in the drink. Once opened, the gas will eventually escape the depressurised can. This takes quite a while if you don't shake the can up before hand.

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However by shaking the can, you create turbulence within the drink and the resultant bubbles provide a swift and frothy escape route for the carbon dioxide.

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Q.� Why does a similar thing happen if you pour a fizzy drink quickly into a glass

A.� Pouring a fizzy drink quickly into a glass creates turbulence and therefore bubbles and extra fizz.

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Q.� Why don't the bubbles rush out from an unshaken can

A.� For a bubble of carbon dioxide to form in a carbonated drink it is necessary for the molecules of gas dissolved in the liquid to break the bonds between the molecules of the liquid. When the bubble is initially forming and very small this demands a relatively high input of energy. As the bubble grows it needs proportionately less energy in relation to its size to get bigger.

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In the unshaken liquid there is no external stimulus to create bubbles. The initial high energy needed to form bubbles acts as a hurdle preventing a large number of bubbles from being produced. However, once the can is shaken the agitation of the liquid produces lots of small bubbles which, needing less energy once formed, grow in size.

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Interested in why your pint of lager goes flat Click here to read all about it or ask a question about why something happens here.

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By Lisa Cardy