A problem about boiling. By definition,boiling is an evaporation which occurs inside the liquid. The saturated pressure has to be equal or greater than the surrounding pressure unless the bubbles inside the water will be squished. under such a condition,if we wanna boil a pot of water,we must heat it to make the saturated pressure equal to the atmosphere. Here comes the problem: If I have a large pot whose depth is 20meter, filled with water, will the boiling temperature at the bottom increase since the pressure at the bottom is more greater than the atmosphere?

Question

raffle_snaffle · Answer

I would think the boiling of water would not increase because the water at the base will lose it's viscosity thus becoming "lighter" floating to the top, while the water on top of the boiling water is cooler that cooler water will replace the hot water and so forth.

huclogin · Answer

If the heat is enough,will there be any bubbles at the bottom of the big pot? If there is a bubble,the saturated pressure must be exactly greater than the pressure of the atmosphere. Namely,the temperature is higher at the bottom.

sahar009 · Answer

Although I've never done the experiment, the boiling temperature below sea level should increase.  This is because the atmospheric pressure increases below sea level similar to the effect of its decreasing above sea level.  According to the pressure vs. elevation table I found at:  

the pressure is  about 114 kPa at 1,000 meters below sea level.  Then, according to the 'Boiling Point Calculator' at  
the boiling point would be about 103 °C.
The underlying physics idea is that the boiling point of any substance is the temperature at which the liquid phase changes to the gas phase. The phenomenon called boiling is the formation and growth of vapor bubbles within the liquid.  The pressure (for a given temperature) sets the density of molecules in the gas bubble. That sets how rapidly molecules leave the gas and re-enter the liquid. The higher the pressure, the more rapidly molecules must leave the liquid if they are to beat the rate at which gas molecules are going back in. The temperature has to go up to raise the rate of molecules leaving the liquid. So at higher pressure, the boiling point is higher.