Thermal gas expansion
It’s an easy trick with gas expansion!
Warning! Only under adult supervision.
- hot water;
- cold water;
- empty bottle.
Put a balloon on the neck of a bottle and submerge the bottle in hot water – the balloon inflates! Immediately afterwards, immerse the bottle in cold water – the balloon deflates.
When a gas is heated, its molecules move faster. As the speed of the molecules increases, the pressure inside the balloon increases. This causes the balloon to swell – as its volume increases, the pressure inside it decreases, and the tension of the balloon grows. Eventually, the pressure inside the balloon is adjusted to compensate for atmospheric pressure and the tension of the balloon itself. When the gas cools, the molecules slow down, and the pressure inside the balloon decreases – it is no longer strong enough to compensate for atmospheric pressure and the tension of the balloon, so the balloon deflates.
Many more cool experiments are waiting for you in the MEL Physics subscription!