Questions tagged [melting-point]

The melting point of a solid is the temperature at which it changes state from solid to liquid.

Filter by
Sorted by
Tagged with
5
votes
1answer
1k views

How does ice melt?

I know that when water freezes, it forms a crystalline structure created by the hydrogen bonds between polar water molecules. Also, I know that during a phase change, the potential energy of the ...
1
vote
1answer
214 views

Would a melted crystal recrystallize back into the same lattice structure when frozen?

Two things that I'm not sure about melted crystals: For a material that has only one possible crystal structure, would freezing cause it to recrystallize, or could it become amorphous upon freezing? ...
6
votes
3answers
15k views

How can sodium chloride melt ice or keep it frozen?

In European countries, they use $\ce{NaCl}$ or $\ce{KCl}$ to melt ice during the winter season. In Asian Countries, they use $\ce{NaCl}$ to keep the ice without melting, for example in ice cream and ...
3
votes
0answers
74 views

Is it possible, given a target temperature, to create an alloy that melts at precisely that temperature?

Assuming the target melting points are between the melting points of mercury and tungsten, is it possible, given a target temperature, to create an alloy (or compound) composition that has a direct (...
8
votes
1answer
31k views

Why do the boiling and melting points decrease as you go down group 1 and vice versa for group 7?

I used to think that because an alkali metal needs to lose one electron to complete its outer shell, when the atom increases in size (atomic radius), the electron would be easier to lose as the ...
3
votes
2answers
2k views

At what temperature (in kelvin) are most of the elements on the periodic table liquids?

This question is out of pure curiosity. At what temperature are a majority of the elements on the periodic table in a liquid state/phase of matter? For the purpose of this question, assume the ...
0
votes
1answer
782 views

How to create liquid carbon, and what kinds of properties does it have? [duplicate]

Carbon sublimes at about 3915K. In a high pressure environment, shouldn't it be possible to create liquid carbon at high temperatures? Has this ever been done? What does it look like and what ...
0
votes
1answer
156 views

Why there is a non-linear trend on the melting points for period 2 elements, especially Na to Si?

Using the knowledge of periodicity from high school cannot explain this, what it tells me is just metallic bonding. The model of delocalised electron from a metallic lattice can explain the increase ...
5
votes
3answers
19k views

Why do the melting points of Group 15 elements increase upto Arsenic but then decrease upto Bismuth?

The boiling points of group 15 elements increase on going down the group (or, as size increases) but the same is not true for the melting points. The melting points increase from $\ce{N}$ to $\ce{As}$ ...
1
vote
2answers
2k views

Supercooling, freezing point depression, and finding the right freezing point

Pure liquid can be supercooled below its freezing point. Conversely, impurities in the liquid will cause a freezing point depression. How then is the freezing point accurate?
1
vote
0answers
2k views

Why does melting point depend on external pressure?

The melting point of a substance is the temperature at which the solid form's vapor pressure equals the liquid form's vapor pressure. I read that the vapor pressure of something depends ONLY on the ...
6
votes
2answers
3k views

Melting points of NaCl and RbCl

Why is the melting point of $\ce{NaCl}$ more than that of $\ce{RbCl}$ ? Using Fajan's Rule of polarizing power, $\ce{RbCl}$ has more ionic character and thus should have a higher melting point.
1
vote
0answers
1k views

Why are the melting points of Sb and Bi lower than that of As?

My book says it has something to do with the inert pair effect. And unlike As, Sb and Bi tend to form 3 covalent bonds rather than 5. I don't understand what's really going on here.
1
vote
1answer
364 views

Can I melt Barium Titanate powder into a cylinder and preserve the high dielectric?

I would like to make various solid forms of Barium Titanate e.g. cylinders, discs. Barium Titanate powder seems widely available and has a melting point of 1,625'C. Can I melt it in an iron forge ...
0
votes
1answer
936 views

Melting and boiling point comparison

Graphite, silica and diamond are covalent compounds and still they have high melting and boiling points. Why?
0
votes
1answer
1k views

How to calculate the boiling point of a solid substance?

Say that I have a solid substance; I know its density, mass, volume, melting point, specific heat, the pressure which it is under, and nothing else. (for now.) How do I find the heat at which it ...
0
votes
1answer
129 views

Can you call a table frozen? [closed]

Someone has argued that the table sitting in front of us is 'frozen'. I do agree that the table has a freezing point. The table has a melting point, but that is beyond the ignition point and the ...
2
votes
0answers
2k views

Why there is an exception in melting and boiling point in p block?

Why is the boiling point and melting point of 15th group and 16th group has an exception? We know that as molecular mass increases boiling point and melting point also increase. So, down the group 15 ...
4
votes
1answer
1k views

Changes in freezing point of sodium acetate

Background: I was recently playing around with some reusable heat packs, the kind that operate by phase change of sodium acetate trihydrate and noticed that they didn't reach the temperature that I ...
1
vote
2answers
952 views

Experimental melting-point of Arm-and-Hammer sodium bicarbonate is remarkably high(?)

Online literature reports the melting point of $\ce{NaHCO3}$ as ~50 deg. C. Using a standard Mel-Temp II melting-point apparatus and a standard alcohol thermometer, I didn't observe any melting of ...
28
votes
2answers
6k views

What happens if you cool water in a container too small for it to freeze?

Freezing a full bottle of water tends to shatter the glass bottle. What if you used something tougher than glass, like diamond? What would happen if you kept dropping the temperature, but restrained ...
1
vote
1answer
2k views

Why do ionic compounds have higher melting and boiling points despite having smaller radii?

Why do ionic compounds have higher melting and boiling points despite having smaller radii? I thought that the closer the two ions are, the larger the repulsive force, and therefore it should rather ...
6
votes
0answers
133 views

Seeking titanium compound, melting point <1600 °C, decomposes to TiO

The title says it all. I’m new to glass making, and I need a titanium compound that will render me $\ce{TiO}$ through decomposition, and has a melting point under 1600 °C. Hopefully I can get one ...
6
votes
1answer
20k views

Trend in the melting point down the group

We know that the atomic radii increases down the group. So, less energy is required to pull out the outermost electron as we go down the group, hence, gradually melting point decreases down the group....
3
votes
1answer
3k views

Boiling/melting points of cyclohexane and cycloheptane

I’m looking at a chart in my book, and while cycloheptane has a higher boiling point than cyclohexane like I’d expect, cycloheptane has a melting point of −12 °C, while cyclohexane has a melting point ...
18
votes
5answers
12k views

Which substance has the highest temperature range between melting and boiling point

Which substances exist that are normally liquid and that will not freeze nor boil even at relatively low/high temperatures as compared to the freezing and boiling points of water? Or how can I ...
7
votes
4answers
58k views

The effect of air pressure on the melting point

What is the effect of air pressure on the melting point of a substance? a) No effect b) The melting point increases when the air pressure increases c) The melting point decreases when the air pressure ...
6
votes
1answer
704 views

At the eutectic point, what is the effect on the melting point of adding impurities?

At the eutectic point, what is the effect on the melting point of adding impurities? Increase the melting point Decrease the melting point No effect on melting point I know adding ...
5
votes
1answer
146 views

Are there compounds that melt under their own weight?

Is there a compound that can melt under its own weight? That is, a block of such material remains solid when put horizontally but starts to melt when put vertically or remains solid in microgravity, ...
11
votes
1answer
14k views

Why does magnesium have an exceptionally low melting point?

Why does magnesium have a lower melting point than both calcium and beryllium? It does not seem to fit into the group trend.
11
votes
2answers
1k views

Why is the melting point of p-toluenesulfonic acid monohydrate higher than that of anhydrous p-toluenesulfonic acid?

Why is the melting point of p-toluenesulfonic acid monohydrate higher than that of anhydrous p-toluenesulfonic acid? Compare for example the melting point of benzenesulfonic acid hydrate, which is ...
8
votes
2answers
4k views

Predicting melting points of substances based on their molecular/atomic structure

Wouldn't it be great to be able to predict the melting point of a metal based on the atomic number and not by looking in some table for the value that was measured experimentally by someone else? Or ...
9
votes
3answers
21k views

Can you melt wood?

We talked about it in our chemistry class but we couldn't get to a conclusion, any help?
-1
votes
1answer
322 views

Why/How am I calculating freezing point depression wrong?

What is the freezing point of water made by dissolving $\mathrm{10.11~g}$ of magnesium chloride in $\mathrm{86.03~g}$ of water? The freezing-point depression constant of water is $\mathrm{1.86~^\...
3
votes
1answer
1k views

Household Melting Point Standards

I'd like to accurately calibrate a digital thermometer I'm building in the range of $50^\circ$ to $120^\circ$ Celsius. I'm aware that one can buy various chemicals that have melting points in this ...
2
votes
1answer
607 views

Why does the mixture's temperature change while phase transition?

Consider a mixture made up of alcohol and water at room temperature. If I freeze this mixture, why does it change its temperature during the phase change? I don't understand the difference between ...
3
votes
1answer
1k views

Molecular weight determination from freezing point depression

Which is the better solvent for molar mass determinations by freezing point depression, benzene or cyclohexane? Which is the better method for molar mass determination, freezing point depression or ...
4
votes
3answers
9k views

How do we predict the order of melting points of group 1 and group 2 halides?

I get really confused by this: The order of melting points of group 2 chlorides is: $$\ce{BaCl2 > SrCl2 > CaCl2 > MgCl2 > BeCl2}$$ This is completely understandable by Fajan's Rules. But,...
6
votes
0answers
975 views

Why does magnesium have the lowest melting point of all earth alkalis? [duplicate]

Why does magnesium have the lowest melting point of all earth alkali metals?
1
vote
2answers
2k views

how to separate gamma-butyrolactone from N-methyl-2-pyrrolidone

Since these two chemicals have different freezing temps (pyrrolidone is $-11~\mathrm{^\circ F}$ [$-24~\mathrm{^\circ C}$] and $\unicode[Times]{x3b3}$-butyrolactone freezes (also called melting) at $-...
3
votes
1answer
8k views

Lowest freezing point room temperature liquid?

What substance that is liquid at STP has the lowest freezing/melting point? I think it's either 2-methylpentane or 3-methylpentane, but I get different numbers from different sources.
13
votes
1answer
67k views

Boiling and melting point of trans- and cis-but-2-ene

The boiling point of trans-but-2-ene is lower than that of its cis isomer but the melting point of the former is higher than the later. Why is it not following the same order? Is there any factor of ...
0
votes
2answers
2k views

How to rationalise the difference in the melting points of acids and alcohols with inter molecular forces?

Acids: arachidic acid, palmitic acid, lauric acid, etc. Alcohols: butan-1-ol, pentan-1-ol, etc. The melting points of acids with $\ce{-COOH}$ at the end compared to melting points of alcohols, $\ce{...
6
votes
2answers
1k views

Can powdered beta-tin be made from raising the temperature of alpha-tin?

When white tin ($\beta$-tin) is cooled to a temperature below $13.2\ \mathrm{^\circ C}$, it creates the allotrope of gray ($\alpha$-tin), a gray, amorphous powder. My question is that once you have ...
18
votes
4answers
19k views

How to RAISE the melting point of water?

It is common that adding common salt into water will lower its melting point. But, is there any way to RAISE the melting point of water? Does it lower the boiling point of water as well? Why?
3
votes
1answer
901 views

Why is the pure tungsten (W) melting point higher than that of its oxides (either WO3 or WO2)?

Why is the pure tungsten ($\ce{W}$) melting point way higher than that of its oxides $\ce{WO3}$ or $\ce{WO2}$? And why does pure $\ce{Al}$ react differently? I.e. the oxides have a higher melting ...
2
votes
1answer
2k views

Effect of inductive effect on boiling point,melting point and dipole movement

In my book the following was written:- Inductive effect is a permanent effect operating in the ground state of the organic molecules and hence is responsible for higher melting point, boiling point ...
6
votes
2answers
7k views

Melting and boiling points of benzene and fluorobenzene

This species is a derivative of benzene, with a single fluorine atom attached. Its melting point is -44 °C, which is lower than that of benzene, indicative of the remarkable effect of fluorination ...
2
votes
1answer
2k views

Is there a material that reduces copper melting point and completely dissolves?

Is there any material that you mix/alloy with copper that will result in something that behaves similar to plastic (that is at room temperature it is solid, at maybe 500K or similar it can be easily ...
104
votes
5answers
82k views

How do you melt metals with super high melting points?

At the Renaissance fair a few years back I was watching a smith forge metal into shapes. During this time a very odd question came to me. I was wondering what the furnace was made of. My logic stated ...