# Tagged Questions

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### How much energy is released by decompressing water?

How much energy would be released if 2L of (relatively pure) water compressed to 1L at room temperature was suddenly decompressed to atmospheric pressure? Even a first-order approximation would be ...
1k views

### What is the status of Mpemba effect investigations?

There is this puzzling thing that is called Mpemba effect: paradoxically, warm (35°C) water freezes faster than cold (5°C) water. As a physisist, I've been asked about it several times already. And I ...
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### Why does hot water freezes faster than normal water? [duplicate]

What is the reason behind hot water gets Freezes faster than normal water when we keep both the hot and normal water together in freezer ?
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### Does Ice made with hot water melt faster than ice made with cold water?

This is an other side of the coin question about the freezing of hot water vs cold water, called the Mpemba effect.
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### Why is ice made from boiled water clear?

A common trick to make clear water ice is to boil pure water prior to freezing it. Why does that work and what are the white inclusions in ice that was made from unboiled tap water?
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### Does ice made out of salt water melt slower than ice made of pure water?

I'm trying to make this whole bunch of ice bottles to cool down my little aquarium. What I want in the ice bottles is that, fter freezing the whole bottle full water into ice, I need the ice to melt ...
1k views

### Is there a temperature at which ice is denser than water?

Normally ice would float on water because its density is less compared to that of water as a liquid. But is it possible that its density will increase due to a very low temperature or is ice in any ...
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### Hexagonal shape of snow flakes [duplicate]

As we know snowflakes has hexagonal shape. My question is why is that? and Is there any mathematical model which can explain that particular geometric shape of the snowflakes?
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### Why isn't ice a good electrical conductor?

Water can conduct electricity, and some solids can conduct. Why can't ice? Are ice molecules too packed together to let valence shell electrons bounce across each other to create electrical charge? ...
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### Lake Ice Temperature

Given: A lake with an established sheet of ice of some nominal thickness covering it. It is night (no radiant energy from the sun). No wind. Air temperature -10 degrees Celsius. Will the ...
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### How do ice spikes form?

I recently saw this picture posted on Twitter which shows a so-called ice spike rising from an ice cube tray. I have read the Wikipedia page, but it doesn't mean much to me. My instinct was that it ...
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### Why did my frozen water bottle explode when I opened it after it defrosted a bit?

Last night I filled a 20 fl oz bottle (http://www.thenibble.com/reviews/main/beverages/soft-drinks/boylans-mash.asp) with lukewarm water from my tap. I filled the bottle pretty much to the brim, ...
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### Does water turn solid under deep ocean because of high pressure?

I know that we can make water solid with high pressure, so I think water will be solid in the deep ocean? If that is true, the depth of the ocean would be limited because water will become ice? ...
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### How cold does this ice have to be to freeze this water bottle solid?

We are at sea level in a room that is 21 celsius. We have 1 liter of sterile water with a temperature of 21 celsius in a normal plastic bottle. We have a 20 liter bucket of ice cubes, consisting of ...
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### How can removing energy from a system do work? (ice)

Water freezing into ice expands, damaging roads, breaking rocks, etc. To my understanding, this is doing work (in a physics sense) by removing energy from the system. How is this possible?
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### Why is this ice cloudy at the center and has a transparent layer?

This fell at my place during a hailstorm. I can not figure it out why it is like this.
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### Melting ice: reversible or irreversible?

I am looking into whether the melting of ice (or any substance for that matter) at constant pressure and temperature is reversible or irreversible. Different sources say different things, and it may ...
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### Experiments on the melting of snow?

When snow melts there are three main variables: the temperature of the air, the altitude of the sun, and the distance of the sun from the earth (which changes because the earth moves in an ellipse ...
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### Would High Explosive helped free Shackleton's ship, trapped in pack ice?

This question is based on physical concepts regarding presssure waves and crystallography, but I thought it might be helpful to include a brief historical context first. From Wikipedia: Loss of Polar ...
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### Ice bath is always 3C, why?

I've always learned that a mixture of ice and water should reach equilibrium at approximately 0C. I've actually tried to create that a number of times in different contexts and always fail. First, ...
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### Is ice harder than steel?

While trying to fix our garburator, I found a couple sites claiming that you can sharpen the blades of your garburator by forcing it to process ice. From my understanding though, that would only be ...
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### Why did my liquid soda freeze once I pulled it out of the fridge and opened it?

This isn't a duplicate to "Why did my liquid soda freeze once I pulled it out of the fridge?". My question is why soda froze after it was opened. Opening a can or bottle seems to have a larger effect ...
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### Why is there ice at the Earth's poles? [duplicate]

I beg your pardon for such a silly question, but I've never really understood the explanation they gave in the Geography textbooks. If the slanting Sun's rays due to the Earth's axial tilt can cause ...
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### Will throwing oil on snow help it melt faster (significantly)? [closed]

The main thing that melts snow is the sun. Indeed, without the sun, the air itself would eventually turn to snow. The problem is, the sun melts snow inefficiently. The sun emits radiation (a lot of ...
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### Physics of waves under an ice road

As wikipedia writes, While easier to drive across in the winter than land, roads over water present a great danger to anyone using them. Speeds are typically limited to 25 km/h (16 mph) to ...
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### Fermi estimate for ice nucleation timescale

My friends in a Cryo-EM lab freeze their very samples quickly, a process they call vitrification. The timescale for this process is milliseconds (from wikipedia): The production of amorphous ice ...
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### Do sodium chloride(ions) melt the ice or not?

My question is this, In European countries, they use NaCl or KCl to melt ice during the winter season. In Asian Countries, they use NaCl to keep the ice without melting. (Ex- Ice cream boxes, Beer ...
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### Ice skating, how does it really work?

Okay, some textbooks I came across, and a homework assignment I had to do several years ago, suggested that the reason we can skate on ice is the peculiar $p(T)$-curve of the ice-water boundary. The ...
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### Are bubbles in ice at a lower or higher pressure than atmospheric pressure?

When water phase-transitions into ice it expands. The water usually contains dissolved air. Freezing forces the air out of the solution into bubbles. Are these bubbles at a lower or higher pressure ...
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### Why does ice melts faster near the surface of water?

I had a few frozen bottles and while they were melting I saw this: in all of the bootles, the ice seems to get thiner near the surface. I have searched a bit and I've found this video that shows ...
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### Are There Any Theories To Explain Why Ice Freezes in Orthogonal Patterns on Surfaces Such as Glass

If one examines the following image: One will notice that the ice is freezing in this characteristic criss-cross pattern. Are there any theories to explain this behavior? I've seen this on car ...
4k views

### Why is ice less dense than water?

The answers to this question explain that ice is less dense than water because it has a "crystal structure", but they dont explain what exactly that is and why this happens, also I saw this answer ...
49k views

### Why does ice melting not change the water level in a container?

I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a ...
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### Why is it easier to glide on sharp ice skates than on dull skates?

There have been previous questions (e.g. here and here) on Physics.SE about the mechanism that makes ice skating possible. Reviewing these, as well external references, it seems pretty clear that the ...
5k views

### How fast does an ice cube melt in a microwave?

I have noticed that when I microwave an ice cube it appears to melt more slowly than I would expect. For example, an equal volume of water starting at 0 deg C would probably be at boiling point before ...
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### Is it possible to mix a drink with a non-standard phase of ice?

Would it be possible to safely cool and drink a glass of water with anything else than the Ih form of ice? Here and here you can see that some alternative forms of ice have a higher density than ...
1k views

### What's the best (practical!) shape to maximize the rate of heat transfer?

I want to cool down a lot of water with a huge ice cube. What's the best shape to maximize the rate of heat transfer?
47k views

### Why does ice have a lower density than water?

Can someone explain me why is ice less dense than water? As I know, all solids are usually denser than the liquids (correct me if I am wrong).
8k views

### Why does an increase in pressure raise melting point?

I've heard that if you increase pressure in a system that has ice in it, then its melting point will increase. However, I would've thought that it would decrease the melting point as the ice would ...
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### Does ice melt slower in space?

If you have an ice block in the International Space Station would it melt more slowly than on Earth at the same temperature and pressure. The reason I ask is that ice can melt due to pressure. The ice ...
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### Why doesn't water get 'increasingly thicker' as it gets colder?

It's my understanding that the colder liquids get (or anything else for that matter) the slower the constituting particles move. That being the case, why is H$_2$O either 'water' or 'ice'? Given that ...
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### Does wax go through a sharp phase transition when it melts?

When ice melts, the system goes sharply from being solid to being liquid. There is no intermediate state where it is soft. This is a true phase transition. The thermodynamic potential is not an ...
3k views

### Does an ice cube change its core temperature as it melts?

Let's say we have an ice water solution in an ambience with room temperature, i.e. there is a permanent exchange of energy. Let's suppose the ice cubes were from the freezer, which is at $-18°C$. The ...
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### What will be the affect of Global Warming if Polar Ice melts? [duplicate]

Due to global warming, all the polar ice melts & sea level increases, with increase in humidity. Angular momentum of ice at pole is, very low. Due to shift of water, from pole to equator, it's ...
1k views

### Why is ice more reflective than liquid water?

Why is ice more reflective (has higher albedo) than liquid water? They're both the same substance (water). Is something quantum mechanical involved?
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### Ice cube left in water at 0 °C for a thousand years

Let's say we take an ideal calorimeter with a liter of water at +5 °C and throw a 5×5×5 cm cube of ice having temperature of –70 °C. I choose these initial parameters so that the stationary ...
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### can ice crystals be molded into a structural shape in space

I know that water exposed to vacuum space first boils and then turn into vapor (sublimates) . Is it possible re use this vapor say inside a pressurized membrane, to mold it into a solid ice structure, ...
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### Why is the temperature of the ice/water bath not dependent on the barometer pressure, as was the temperature of the boiling-water bath?

Part of a laboratory experiment question set. Why is it that the known temperature of the boiling bath can be accurately determined from the days atmospheric pressure but the atmospheric pressure is ...
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### How can towtrucks tow a heavy truck on icy roads?

(This isn't hardcore physics, but bear with me. I've been watching too much Highway Thru Hell and I'm curious about this) A common problem on the Highway Thru Hell TV-show is trucks stuck on an icy ...
260 views

### Air bubbles in Ice and cause for their shape?

I was looking at the ice formed in my refrigerator and found out there were a lot of air bubbles inside it. The shape of the air pockets seemed strange to me. There were many small spherical ones ...