It gets larger because well let me give you an example so today in class we looked at a lava lamp with wax inside and there was a lightbulb at the bottom. we watched as the wax floated up because the molecules inside the wax spreads out and makes the wax less dense. the wax floats up because (which is related to the balloon getting bigger) the wax is getting less dense and the particles get bigger which ALSO makes the wax less dense. hope this helps and hope you can relate it to your problem! say thanks if I did help AT ALL! :)
The air that is trapped inside the balloon starts expanding when the balloon is heated. This happen because the air molecules move away from each other. This results in the expansion of the balloon.
In the whole process, the mass of air trapped inside balloon do not change. Also, there is no change in the balloon itself. Thus mass remains the same. Though, the volume changes due to expansion of the balloon.
Sir Richard Branson's personal dilemma is that he is concerned about the environment and climate change, but he has made his fortune with an airline industry that contributes to the greenhouse gases.
