## rvc one year ago When u take a piece a paper ,give fire to it and put it in a glass bottle quick then keep the boiled egg on the mouth of the bottle.egg cover should have been removed.the egg gets into the glass bottle.why is it so?

1. doc.brown

PV=nRT

2. doc.brown

R is the ideal gas law constant, very important for calculation, not important for understanding this. Let's ignore it for now. P is pressure, V is volume, n is the number of molecules, and T is the temperature.

3. doc.brown

If the number of molecules doubles, and the temperature and volume stays the same, what happens to the pressure?

4. doc.brown

Pressure * volume = molecules * temperature

5. Mashy

I ll give you a clue, fire requires oxygen.. so it consumes oxygen!

6. doc.brown

That doesn't change the number of molecules by enough to make much of a difference. The volume is proportional to the heat.

7. rvc

@waterineyes

8. ProfBrainstorm

doc brown has mentioned the gas law p=nRT/V and it should be clear from this that increasing the number of molecules in the volume, or increasing the temperature, will tend to increase the pressure. It seems to me that an increase in pressure in the bottle would tend to force the egg out of, not into, the bottle. The clue from mashy seems like a more promising idea . . .

9. Mashy

lol.. this is 5 months old post.. xD

10. ProfBrainstorm

I'm sure that the combustion using up the oxygen is the essence of the solution, but what about the products of the combustion ? Considering the gases, before the combustion we have oxygen, but after we have carbon dioxide and steam - even more gases ! Could it be that the drop in pressure arises from the rapid condensation of the steam that is produced ? Looking at the chemical balance for burning long chain hydrocarbons$2CH _{2}+3O _{2}\rightarrow 2CO _{2}+2H _{2}O$ suggests that with rapid cooling of the water vapor there should be a one third drop in pressure from the change in the number of gas molecules (assuming complete burning of the oxygen in the bottle) Is this anywhere close to the correct explanation ?

11. ProfBrainstorm

Having put down my pen and paper to do a couple of experiments I think the answer is simply that the egg acts like a valve on top of the bottle. Fire in the bottle heats the air, air expands, pushes its way out past the egg. Air starts to cool, pressure drops, egg makes a good seal and gets sucked into the bottle. My previous explanation is irrelevant nonsense.