# Tag Info

27

I'm really winging this one because the last time I did an equilibrium calculation was 35 years ago! But I'm fairly sure of a partial answer (see discussion at end). A gas's solubility in water (or liquid generally) almost always decreases with increasing temperature. This phenomenon is explained in a way very like the explanation of the increase in ...

19

Ice can be denser than water for certain values of $P,T$. Look at these two pictures taken from here: The darker areas in the second picture denotes areas of greater density. So you can clearly see that when pressure is increased, ice becomes denser than water along the coexistence line. For example at $T=400$ K ice VII is clearly denser than water ...

14

The most immediate answer would seem to be that a great variety of different crystal phases can exist because their long-range order makes it possible to classify them based on the different symmetries of their lattice structure. Since the liquid (or amorphous solid) phase only has short-range order and the gaseous phase doesn't even have that, it seems ...

11

This answer was meant as a comment to @WetSavannahanimal aka Rad Vance but it is rather long and I hit the character limit. The reason for the opaque center should be due to the manner in which the water volume is freezing. Presumably the solution is not mixed and the outside freezes first forming a crystalline (ice) wall through which the gas cannot escape....

9

It is the water vapour present in the air around the bottle, that condenses on the cool surface of the water bottle,not from the water bottle itself.

8

The short answer: Cloudy ice is caused by gases (mainly nitrogen and oxygen) dissolved in the water that come out of solution when the water freezes. The small bubbles trapped in the ice cause the white appearance. Boiling the water removes the air dissolved in it, producing clear ice as a result. Assuming that other impurities don't produce the same cloudy ...

6

Here is a video that shows the ball behaviour you're describing. The phenomenon is explained by the Coandă effect: the tendency of a fluid jet to stay attached to a convex surface. Note that the ball does actually move in a kind of oscillatory motion. This is probably due to the water jet in the video not being highly stable. When more liquid is running ...

5

This phenomenon you are describing is called the Mpemba effect after a Tanzanian student, Erasto Mpemba, who in 1963 noticed the temperature of ice cream affected how quickly it mix freezed, though the effect had been observed much earlier (the earliest known observation of this was by Aristotle in 4 B.C, though Aristotle probably didn't use ice cream). ...

5

Nothing in the laws of thermodynamics forbids multiple liquid phases for a single substance. The only limit is the simultaneous coexistence of at most three phases (at triple points). Water has a solid-liquid-gas triple point and several soid-solid-liquid and solid-solid-solid triple points; see the phase diagram of water and ice. In addition, although not ...

4

$1$ litre of water will remain almost $1$ litre as long as it is in the liquid state, no matter what the temperature is. The following formula gives you an order of magnitude estimate of the expansion: $$\Delta V=V_0\ \Delta T \ \beta$$ where $\beta$ is the coefficient of thermal expansion and $V_0$ is the initial volume. For water, $\beta \approx 10^{-... 4 The electromagnetic field in a medium gets attenuated exponentially. $$\mathbf E = \mathbf E_0e^{-x/\delta}$$ Where$x$is the distance the signal has traveled. Since the power of the signal is proportional to the square of the field, then the power will be attenuated by$P = P_0 e^{-2x/\delta}$. The quantity$\delta\$ is called skin depth. Its the ...

3

I've never been in a jacuzzi, but I'll try to imagine one. I read elsewhere that the bubbles are added using venturi-effect, or using a blower. Main thing is, they aren't pumped together with the water (the pump wouldn't like that anyway). The Venturi effect creates low pressure (suction) by increasing the velocity of the water in a narrow section of the ...

2

I entirely agree with @Vintage in his offered answer to @BarsMonster's question. It seems to me that the question isn't how to make the most accurate, error free measurement for water. Rather, what's a practical method that can give a 1st order, believable result? Placing two clean metal plates reasonably close together where d/A >> 1 and then measuring the ...

2

In general, what you would need to know to completely calculate the situation through, is the wavelength-dependent absorption of your plastic and water and the characteristics of your LED (wavelength, spectral broadness, etc.). And yes, in general, most plastics have IR-absorption (which is why IR spectroscopy is used in plastic analytics). But depending on ...

2

The curvature of the drop is influenced by the liquid-solid, solid-air and liquid-air interface forces. It can be determined by the Young-Laplace equation. For more details see this article

2

I think the answer in this reddit discussion is basically right. But first, I should point out that pure diffusion is excidingly slow. A quick calculation shows that it would take 500 years for an average water molecule to diffuse 1 meter. Of course, in most cases real particles diffuse much faster thanks to small turbulent flows. This already hints at one ...

1

Volume is not a meaningful measure of quantity, for the reason you hint at in your question. You can say how many moles (or grams) of water you drank - more useful if you want to know about the impact on your body chemistry. This is related to my answer about scales measuring in grams rather than Newtons. Can you see how?

1

Tap water has various impurites , which lowers the vapor pressure of the resulting mixture. This leads to a lower boiling temperature.

1

I think the answer is "no" in the case of NaCL (which is what we usually refer to as "salt"). Here are the arguments: First - the dissolution of (NaCl) salt in water is slightly endothermic (5 kJ/mol), but the dissolution of salt in ice is much more endothermic. This is nicely explained in this answer: adding salt to ice creates "ice above its melting point"...

1

From the book Freeze Drying by Georg-Wilhelm Oetjen: Oesterle showed that not only can tBA speed up the sublimation of ice from amorphous freeze-concentrated mixtures, but also similar effects can be achieved with volatile ammonium salts such as ammonium acetate, bicarbonate and formate. In other words, a scientist showed via experimentation that ...

1

There is actually only one disordered phase - from a physicist's perspective, the liquid and the gas are actually the same phase because one can continuously vary the external parameters (temperature and pressure, in this case) to get from the liquid to the gas without passing through any phase transition, because the phase transition line terminates within ...

1

as per conservation of energy, provided heat is used to heat the water, thus it raise its temperature. As molecules are not very tightly bonded in liquids ,they start moving randomly. these movement causes colapsation initially and it gives out some of the energy gained in the form of sound energy of varying intensity/frequency, as there are no any other ...

Only top voted, non community-wiki answers of a minimum length are eligible