Questions tagged [melting-point]

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

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Melting and boiling point trend in Group II

The following picture shows the melting and boiling point trends down group II elements. I have added question marks where the variability in data was rather disturbing (over two hundred degrees ...
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Why does diethylmethylamine have such a low melting point?

According to PubChem, diethylmethylamine has a remarkably low melting point of $-196.0\ \mathrm{^\circ C}$. This is substantially lower than the melting points of dimethylethylamine ($-140.0\ \mathrm{^...
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At what temperature does charcoal burn?

According to some sources, charcoal burns at temperatures as high as 2600 °C (Wikipedia), others (that seem less reliable) say around 1000 °C. I know that it depends on the air flow, but how high of ...
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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 ...
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What makes the first 3 alkanes decrease in melting point while after that they rise?

What makes the first 3 alkanes decrease in melting point (m.p.) while after that they rise? $$ \begin{array}{lr} \hline \text{Alkane} & \text{m.p.}/\pu{°C} \\ \hline \text{Methane} & -182 \\ \...
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Comparing of melting point of dibromo p-xylenes

How to compare the melting points of the above isomers? I know that melting point depends upon the packing of the molecule, more efficient the packing, higher is the melting point. Symmetry in a ...
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57 views

Phantom Material: why formaldehyde doesn't rise my jelly melting point?

Just to be clear, I'm not a chemical but only a electronic engineer which want create a "phantom material" to reproduce the electrical characteristic of epidermis for the analysis of electrodes ...
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2k views

How can a substance have a higher boiling point but lower melting point than another substance?

Looking at 1,3-Butadiene and Isoprene, I'm wondering: why does Isoprene have a higher boiling point, but a lower melting point than 1,3-Butadiene? I'm thinking this might be because the Methyl group ...
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4k views

Intermolecular Forces in Teflon vs Polyethylene

From Wikipedia, polyethylene has a melting point of around $400K$, while Teflon (polytetrafluoroethylene) has a melting point of $600 K$, which is much higher. Besides the increased London Dispersion ...
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73 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 (...
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Why is there no exothermic crystallization peak visible during cooling of PLA and no endothermic melting peak visible during a second heating of PLA?

I am doing lab research on DSC measurement (Heat-cool-heat) for understanding melting characteristics of polymers (PLA, PA6 and PE). During cooling i saw exothermic peak and during second heating i ...
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Comparing melting points of substituted benzaldehydes

The correct decreasing order of melting point for the given organic compounds is: 3 has maximum melting point because of intermolecular hydrogen bonding. I am unable to predict rest of the order ...
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Chemical that won't freeze below melting point

I have an organic chemical (can't say due to an NDA) that has a nominal melting point of 28 °C. When I raise it above this temperature, it melts, but then it will stay a liquid indefinitely at lab ...
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431 views

Reforging tungsten/tungsten carbide temperatures

I was wondering about the reforging of tungsten and the temperature needed. As I understand it, tungsten melts at $\pu{3442 ^\circ C}$ and tungsten carbide at $\pu{2870 ^\circ C}$. However, once a ...
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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 ...
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Are forming coins starting with sodium chloride possible without the clay melting from the molten metal?

Is forming metal coins (specifically ones with copper, nickel, and zinc) possible with these steps: Carve a sheet of sodium chloride so that it is big but not too big and so that the design sticks ...
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1answer
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Why does aluminum chloride have a higher lattice energy than aluminum fluoride?

From the table below (source: McMurry's Chemistry [1, p. 212]), it is evident that $\ce{AlCl_3}$ has a higher lattice energy than $\ce{AlF3},$ even though $\ce{F}$ is smaller than $\ce{Cl}$. Why is ...
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1answer
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Nucleation and Phase Equilibrium at the Melting Temperature

I used to think that at the melting point, the solid and liquid phases are in equilibrium. That’s because the Gibbs free energy change for the transformation is 0, as is characteristic of equilibria. ...
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Crucible design for melting alumina

I'd like to melt alumina in a slow, controlled manner. So I thought a graphite crucible with a tungsten wire wrapped around it for heating would be a good start. To reduce heat losses, I put that ...
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Is there any sort of correlation between melting point and the degrees of freedom for the molecules of a substance?

Suppose I had a solid whose molecules did not have rotational freedom. But if I were able to make it so that the molecules had rotational freedom ceteris paribus, is there a way to tell how the ...
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Explain the effect of intramolecular hydrogen bonding on solubilities in cold and hot water?

There is a statement given in my textbook (Cengage, Organic Chemistry (Part 1), page 4.33) which is as follows: (I edited the statement to make it simpler) One can account for the solubilities of ...
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651 views

How does the melting point of alkynes change with the position of the triple bond?

$$ \begin{array}{cc} \text{1-hexyne}&\pu{-132 ^\circ C}\\ \text{2-hexyne}&\pu{-89.5 ^\circ C}\\ \text{3-hexyne}&\pu{-103 ^\circ C}\\ \end{array} $$ These are the melting points of six ...
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Near melting thermoplastic material accumulates in the sharper corners. What is this phenomenon?

I have a part made of a thermoplastic material. When I heat it up and cool it down, the dimension of the part changes non-uniformly. Somehow the melted material tries to fill the sharper corners. So ...
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1answer
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Hydrates and melting points

Basalt melting point: wet vs dry I had a student ask me this in class the other day; I thought about it, but I still can't work it out. Many mineral and rock hydrates (take basalt, for instance) ...
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670 views

What is the melting point of glycerol in a vacuum?

Can anyone tell me what the melting point of glycerin would be in a vacuum? From researching online (disclaimer: I'm definitely not a chemist) it seems the boiling point is $\approx \pu{170^\circ C}$ ...
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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 ...
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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.
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Is there a correlation between the susceptibility of a polymer to undergo hydrolysis and its melting point?

As per topic, I was wondering why the Tm of the polymers PGA, PLA and PLGA are in the following order. Does it correlate to their ability to undergo hydrolysis? PGA>PLA>PLGA
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ethanol/water %vol/vol and freezing temperature

Main Question: Where can I find a table (or realistic formula) for isopropanol/water %vol/vol mixes and corresponding freezing temperature with public access? Background: Trying to get the freezing ...
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312 views

Which has a high melting point, cocoa powder or cocoa butter?

I have been doing some research into chocolate, and after looking at the chemical compositions of cocoa butter and cocoa powder, struggled to determine which had a formula/structure that would have a ...
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1k views

Melting point in hydrocarbons

Checking out the molecular structure and the melting points of various hydrocarbons I concluded: 1)branching increases the melting point of a hydrocarbon molecule 2)symmetry increases the melting ...
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951 views

How does cross-linking between polymer chains increase the melting point of the polymer?

https://i.stack.imgur.com/uUcQr.jpg Suppose we have this polymer chain. Now, we cross link some chains ( not all ) , so some chains get linked, and others remain as they are. What we now have is a '...
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965 views

Random order of melting points of group 2 elements

Compare the melting points of $\ce{BeF2, MgF2, CaF2, SrF2, BaF2}$. Actual order is $\ce{ BeF2 > CaF2 > SrF2 > BaF2 > MgF2}$. I have worked out the following things while comparing ...
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2answers
641 views

when Al2O3 melts which bonds are broken?

Previously, I was trying to understand why $\ce{Al2O3}$ has a lower melting point than MgO. An answer on quora said Do not confuse the character of the bond between the metal and oxygen with the ...
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3answers
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Melting point of trans-4-methylhex-4-enoic acid and cis-4-methylhex-4-enoic acid

My book said that the cis isomer has a higher melting point. But I dont understand isn't that the trans isomer can pack more efficiently, because the trans isomer less bulky/ create less 'kink' than ...
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1answer
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Melting Lithium foil to make ingot?

I'm not sure of this is the correct spot for this but I am curious about this. I want to make some Lithium ingots. The only source of Lithium I have is the foil from Lithium batteries. My question is ...