# Tag Info

1

The relevant properties of nitrogen at 20°C and 1 atm are: 13.8 standard cubic feet per pound of nitrogen gas. 0.808 specific gravity of liquid nitrogen. 1/13,8 = 0.07246 pounds of gaseous nitrogen per cubic foot. Converting to metric units we get 1.1607 kg/m³ for the density of gaseous nitrogen 1000 kg/m³ equals the density of liquid water. Therefore ...

1

Partial answer in the case of auto-gravity: the Chandrasekhar limit gives the threshold where electron degeneracy pressure exactly counterbalance gravity pressure (after that electrons fall on the nucleus, white dwarf collapse into neutron star). This should provide ingredients to answer your question.

0

For those who may read this later: you cannot find the liquid and vapor phases independently in this way. The reason is that for densities in between the liquid and vapor densities, the system will phase segregate into droplets within the simulation, and so your total density will include contributions from both phases. Consequently you can change the ...

1

I can't speak specifically for organic polymers, but I will try my best for polymers in general. Every bulk polymer is made of thousands polymer chains, which is made of many "mers" (Greek for unit). Consequently we have the name polymer . For many polymers at room temperature these chains are able to rotate, and because the bonds are not 180 degrees apart ...

1

From the diagrams on the webpages you linked, it appears that other ice phases begin to form at around 200 MPa of pressure, and about $-20\text{C}^{\circ}$. Keep in mind normal water freezes at $0\text{C}^{\circ}$, and air pressure at sea level is around 0.101MPa. That means an ice cube made of one of these phases would sublimate or explode very quickly. If ...

1

As you can see from the phase diagram plot in the first link you provided, the only other ice phase which is stable at atmospheric pressure is ice XI, and its density is about the same as that of the most familiar ice phase (ice Ih). The other denser ice phases that you see on the phase diagram are only stable at pressures significantly above 1 atmosphere. ...

1

It was probably just the wind Lakes freeze at their surface because between 0 and 4 degrees C water decreases in density with temperature. That means that the warmer water will sink and the cold water will rise to the surface. This convection will be much faster than any other mode of heat transfer. This means that in the cooling process the water will be ...

4

Several things: first, a stovetop heats the water only (primarily, anyway) by heating the bottom of the pot. This causes a significant thermal gradient. The water is hottest at the bottom and starts to boil there. The microwave heats the water more or less uniformly from all sides of the container, with a penetration depth that you can look up -- i.e. ...

1

When you heat water you increase the kinetic energy of the water molecules. As an order of magnitude estimate, the kinetic energy at a temperature $t$ is about $kT$, where $k$ is Boltzmann's constant. So when the molecules in water (or ice or steam) interact with each other the energy available is roughly $kT$. At the temperature of boiling water this ...

0

What should be mentioned in addition to what has been said in the answers already given, is that at 100°C, the vapor pressure of water equals the standard atmospheric pressure. Now, a glass of water at room temperature is not in thermal equilibrium as long as the relative humidity in the room is not 100%. This leads to water evaporating into the room. But ...

1

@FasEtNefas presents us with this quote: Now suppose a uniform binary mixture [e.g. a CuCr metal alloy] at a high temperature and concentration u∗ is suddenly quenced to a given lower temperature. A commonly occuring situation is that there is a pair of values of u [which is the local concentration of one of the components], say u1 and u2, and a ...

1

Have a look at the following idealised binary phase diagram: The vertical axis is temperature, the horizontal is composition (in mole fraction but weight % would work too here). Say we started from point 1. where the alloy is fully liquid with a well defined composition, say $u$. Now we cool down, following the red line. At some point we hit the black ...

1

Summary Water's temperature corresponds to the concept of average kinetic energy. The actual molecules exhibit a distribution of various kinetic energies. It takes a quantity of energy to boil a quantity of water. For some quantity of water to boil approximately instantly, all its molecules would have to be at approximately the same kinetic energy, which ...

5

If you want to see all water in a container immediately turn to steam, you need a transparent container that you can seal. Fill the container 50% with water and tightly seal it. Place the container on an open flame and let it heat up. While it is heating, walk far away and watch the container through binoculars from some distance (e.g., 50-100 m should do ...

8

Temperature is a measure of average kinetic energy. When you have a kettle of water at 100˚C, some of the water molecules will have more-than-average energy, and some will have less. The more-than-average molecules are the ones that will turn to steam, carrying off their energy and lowering the average (and thus the temperature) for the remaining water. ...

10

Since neither of the answers given so far really answers the question, here's my \$0.02: between convection (the flow of water of various temperatures around the kettle), and the fact that the heating element is at the bottom, the water is at various temperatures at various parts of the kettle at any time. Usually, the hottest is at the bottom, if the kettle ...

-2

A kettle contains a heating element - either protruding into the water or in the base of the kettle. The heating element heats the water that is in immediately contact to the element through heat conduction. Since the water is free to move within the kettle and that hotter water is less dense than cooler water the water that is heated by the element rises ...

95

Energy is needed to convert water to steam. This is called the latent heat of vapourisation and for water it is 2.26MJ/kg. So to boil away 1kg (about a litre) of water at 100ºC the kettle would need to supply 2.26MJ. Assuming the kettle has a power of 1kW this would take 2260 seconds. Given the unexpected interest in this question let me expand a bit on ...

2

If the pressure in the entire pot of water is less than the vapor pressure of boiling water, and substantially equal to the ambient atmospheric pressure, then the entire pot of water will begin to vaporize, including its interior which vaporizes into bubbles. Bubbles form because the ambient pressure surrounding them is less than the vapor pressure of water ...

5

The quoted definition may sound confusing because of the use of "vapour pressure", which is not necessarily related to the liquid-air surface. This can be made clearer by a different example: Suppose you have a water container at room temperature and you heat only a small volume at the centre of the container (by using focused radiation of some sort, for ...

9

Boiling is clearly not a surface phenomenon. But vaporising is. Boiling happens at all the points inside the liquid whereas when vaporising only the molecules at the surface escape into the space above. And it is true that a liquid boils when its saturated vapour pressure equals external (room) pressure. But it is not to be confused with vaporising. ...

1

The total cooling power of a block of ice in water (or other water-miscible liquid) depends only on two things: the mass of the ice, and the initial temperature of the ice. The shape is irrelevant, except in that it changes how fast the ice absorbs heat from the water. If we assume that the cup of water and ice are insulated, and wait long enough for it all ...

Top 50 recent answers are included