Mostly with birthdays and various parties, we see decoration made by colourful balloons which looks amazing and recall the memories of childhood. By seeing it children got excited and enjoy which is inexplicably satisfying about pricking a balloon and watching it go up by ‘Pop’ sound.
Have you ever thought why this happens? Why balloon produces pop sound instantaneously rather than leaking air slowly? This also happens when we prick an airtight packet of chips. Let us find out the reason behind it.
Balloon is made up of an elastic material like rubber, latex, nylon, Polychoroprene etc. due to which the ability of balloon to inflate increases and it stretch to become larger than its original size. Also, the pressure inside the balloon of air is higher than outside, which creates a difference between the surrounding air pressure and the pressure inside the balloon.
Molecules of rubber in the balloon are made up of long molecules, i.e. polymers which are linked together and due to the elastic nature of a balloon it inflate up to a certain limit. But, if that limit is crossed, the tension pulls the cross-links of the chains become too great, causing them to break and Pop! Sound appears of the balloon. Basically, it breaks into two large fragments. But if you inflate it until it burst spontaneously, you get dozens of pieces.
When you prick a balloon, a tiny hole is made on the surface of it. But, if it is slowly inflated it will not produce pop sound as the air will leak slowly until it was completely deflated and return to its original size. However, if the balloon is inflated to its maximum size due to which the molecules of the polymer are in a lot of tension. In such a way that every point on the surface is uniformly pulls in all directions which keep the balloon tightly stretched. The moment when a tiny hole appears on the surface, rubbers of the balloon now will no longer being pulled uniformly in all the directions. This causes the net force to pull the skin away from the hole, which further increases the hole’s size and balloon explodes with popping sound.
Don’t forget it that the pop sound is created after a sudden pressure change due to the rapid expansion of the air inside the balloon. All this process happens in a fraction of seconds.