The melting point of a solid is the temperature at which it changes state from solid to liquid.
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Why is aluminium has an unexpectedly low melting point?
Al has a similar melting point with Mg, but Al has 1 more electrons than Mg, shouldn't the metallic bond be stronger?
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109 views
Why is the melting point of iodine so high compared to ammonia? What about Zn and C(diamond)? [closed]
Increasing order of melting point by searching the temperature on the web:
$$\ce{NH3} <\ce{I2} <\ce{Zn}<\ce{C_{diamond}}.$$
The idea I have read on "Chemistry: The Central Science" by ...
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0answers
55 views
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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1answer
156 views
Applying salt to roads to melt ice--is it special? [duplicate]
Most everyone is familiar with applying salt to the roads during winter to melt ice.
I'm wondering if there's anything special about placing salt on the roads or would any other substance, sand for ...
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1answer
47 views
Why are highly branched alcohols solid?
Usually branching (or decrease in surface area) leads to increased volatility. But in case of alcohols, my book states that:
The higher alcohols (butanols to decanols) are somewhat viscous, and ...
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1answer
39 views
Does the van der Waals force not affect the alkali metal 's trend of decreasing melting points down the table? [duplicate]
Melting and boiling points increase further down the halogen group, but they decrease further down the alkali metal group. I know that the former's trend has to do with the van der Waals force, but I ...
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47 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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3answers
104 views
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
125 views
Why is the difference between the melting point and boiling point large for some compounds, and small for others? [duplicate]
I was looking at a list of melting and boiling points of various compounds and I realised some had very large differences while some have very less differences between their melting and boiling points....
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1answer
54 views
Predict melting point of water CaCl2 solution
I'm doing a science project for my school. I experimentally measured the melting point of water-salt solutions, and I want to compare my results to theoretical melting points, but I encountered a ...
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0answers
29 views
Change of properties from Propanol to Butanol [duplicate]
This might be a silly question, but I couldn't find a nice answer. Reading the properties of short alcohols I found some data and made this table:
PS: I apologize for the footnotes. S= solubility.
...
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0answers
16 views
How to know if a sample suffered descomposition during melting point? [closed]
If I take a sample in order to determine its melting point, how do I know if that sample suffered a descomposition?
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1answer
422 views
Why does neopentane have a higher melting point than n-pentane?
Why does neopentane have a higher melting point than n-pentane?
I know that we can say that, due to stacking, it has a higher melting point as it freezes easily. But then, why doesn't this happen in ...
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0answers
45 views
What makes the first 3 alkanes decrease in melting point while after that they rise?
$$
\begin{array}{c|c}
\text{Alkane}&\text{Melting point}\\\hline
\text{Methane}&\pu{-182^\circ C}\\
\text{Ethane}&\pu{-183^\circ C}\\
\text{Propane}&\pu{-188^\circ C}\\
\text{Butane}&...
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1answer
37 views
Which melting point would indicate a metallic structure? [closed]
Question
If you have three substances with three different melting points;
445 °C
1907 °C
-7 °C
Which of these would most likely have a metallic structure?
I understand that the ...
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0answers
66 views
How does the melting point of alkynes change with the position of the triple bond?
$$
\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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0answers
124 views
Freezing of alcohol water mixtures below the triple point pressure of water
What happens when you try to lower the pressure of an alcohol-water mixture below the triple point of water? To give a specific example, the freezing temperature of a 50-50 (by mass) ethanol-water ...
3
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1answer
166 views
For two compounds that are symmetrical, why does the more compact one have a higher melting point?
In this post, I refer to two molecules B (Di-tert-butyl ether) and C (Dibutyl ether).
Wikipedia: Di-tert-butyl ether (B)
b.p. 107.2 C
m.p. - 61 C
...
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2answers
306 views
If we start heating a substance, does it melt when we break its intermolecular bonds? [closed]
I was reading the 2 following posts:
Do substances melt when we break their intermolecular bonds?
Is melting/boiling point of ionically bonded substance higher than of covalently bound?
Altough ...
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0answers
16 views
What is the reason behind the 2% decrease in silver metal composition just after melting the raw silver alloy (55% silver)? [duplicate]
I determined the silver composition from an alloy obtained from a jeweler to be 57% and wanted to extract silver out of it. However, upon melting around 5 kgs of alloy, the silver composition went ...
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1answer
45 views
What is the reason behind the 2% increase in silver metal composition just after melting the raw silver alloy (55% silver)? [closed]
I determined the silver composition from an alloy obtained from a jeweler to be 55% and wanted to extract silver out of it. However, upon melting around 5 kgs of alloy, the silver composition went up ...
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2answers
108 views
Does granite become soft as modelling clay at 2000 °C?
As Wikipedia tells us, it consists of $\ce{Al2O3}$ ($14.42\%$) (alumina) whose melting point is $\pu{2072^\circ C}$, and $\ce{SiO2}$ ($72.04\%$) (silica) whose melting point is $\pu{1713^\circ C}$. So ...
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2answers
273 views
Melting ice with salt - how does it start?
I know that salt reduces the melting point of ice. I can see how a little bit of salty water can melt ice to water which can dissolve even more salt. But how does it even start? There is ice, which is ...
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1answer
2k views
Why is the melting point of PCl3 less than that of PCl5?
From just the IB chemistry bonding chapter information, you would normally deduce that $\ce{PCl3}$ and $\ce{PCl5}$ are both covalent molecules.
However, as $\ce{PCl3}$ has a dipole moment, it has ...
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0answers
76 views
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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4answers
179 views
Is it possible to freeze water by dissolving a salt?
Theoretically, by dissolving a salt in water the melting point lowers, approximately 1.86 K kg/mol, making it more difficult to freeze water. However, the process of dissolution of certain salts is ...
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0answers
27 views
Why is there such a big difference between the levels of precision that we know gallium's boiling and melting points to? [duplicate]
For example, Wikipedia lists the melting point of gallium at the very precise 302.9146K while it lists its boiling point at the much less precise 2673K. Is this down to experimental issues or is there ...
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1answer
799 views
Boiling points of HF, HCl, HI [closed]
I'm really confused over how to weigh the molecular mass with intermolecular forces such as hydrogen bonding in HF in terms of figuring out the melting points in relation to each other.
I know that ...
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1answer
1k views
Suggest why melting point of sodium iodide is lower than the melting point of sodium bromide [duplicate]
I would assume this has something to do with bonding and perhaps density, but I haven't the faintest where I'd begin.
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1answer
81 views
Is molten potassium nitrate possible?
Is it possible to melt potassium nitrate without it decomposing into potassium nitrite and oxygen? If so when it solidifies does it keep its oxidizing properties?
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2answers
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How do you tell which molecule has a higher melting point?
In the instance of comparing $\ce{NaCl}$, and $\ce{Al2O3}$; which one has a higher melting point and why?
I have learned the following inter molecular forces, however the question the chapter is in ...
8
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1answer
247 views
How to separate paracetamol and caffeine?
How do you separate paracetamol and caffeine using high-school laboratory equipment?
I was thinking about using the fact that paracetamol has a lower melting point (169 °C) compared to caffeine (...
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0answers
23 views
Eutectic freezer-pack solution based on seawater
I am filling airtight PVC containers to use off-grid as freezer packs for food storage in foam insulated passive coolers, and "swamp cooler" air con when temps are dangerously high.
I have used ...
5
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1answer
187 views
Chemical reaction between dichloromethane and solid carbon dioxide
I studied heat transfer liquids with low melting point (coolants), and how fast their temperature decreases when they are contacting with solid carbon dioxide. Nearly all liquids (brines, glycols etc.)...
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1answer
625 views
Why polymers have a range over which they melt instead of having a specific melting temperature? [closed]
Does it have something to do with the fact that all chains are not of the same length?
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66 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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1answer
495 views
Baking soda + oil solubility
I have a question regarding the solubility of baking soda (bicarb soda) in oil. I am pretty sure that it has poor solubility, but I have a chemistry dilemma and cannot seem to solve it.
I make all-...
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3answers
3k views
Melting point of obsidian
Hi I have tried 4 experiments at various temperatures to melt obsidian.
At varying temperatures it just bubbles up and I don't seem to reach a melting point.
Do you know what gases obsidian might ...
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1answer
1k views
Why is the melting point of a substance is the same as its freezing point? [closed]
Melting point = Freezing Point
Why is the melting point of a substance is the same as its freezing point?
3
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1answer
1k views
How do you melt magnesium without causing its combustion?
How do you melt magnesium without causing its combustion?
I own a foundry capable of reaching temperatures around 2000 °F, and I recently bought some magnesium for melting before doing my research. I ...
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2answers
1k views
Why does branching decrease density and melting point?
The general explanation given is that the chains are further apart, so the intermolecular forces are less, and as they are further apart, they occupy more volume, and the density is lesser. But the ...
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0answers
304 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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1answer
3k views
Why does naphthalene have a higher melting point than both water and diphenylamine?
We learn that polar compounds have higher melting and boiling points than nonpolar compounds due to strong intermolecular forces such as hydrogen bonds and dipole-dipole interactions.
Naphthalene is ...
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1answer
3k views
Why is the melting point of magnesium oxide higher than aluminium oxide?
There's a graph of the melting points of period three oxides. The melting point of Magnesium Oxide is several hundred Kelvin higher than Aluminium Oxide. I can't find any explanations for this on the ...
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1answer
261 views
Melting points of compounds?
Compare the melting points of:
1) $\ce{BeSO_4}$
2) $\ce{CaCO_3}$
3) $\ce{BaCO_3}$
4) $\ce{SrCO_3}$
Okay, so there are a few statements given by my teacher:
1) Thermal stability ...
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1answer
71 views
Confusion in comparing melting point
We have to compare melting points of $\ce{LiH}$, $\ce{NaH}$, $\ce{KH}$, $\ce{CsH}$. I know the melting point of an ionic compound is more than that of a covalent compound.
So according to Fajan's ...
7
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1answer
3k views
Why alkanes containing even number of carbons can be packed more efficiently than alkanes with odd number of carbon atoms?
Variation of boiling and melting points of alkanes with increase in the number of carbons
The odd-numbered alkanes have a lower trend in melting points than
even numbered alkanes. This is because ...
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0answers
323 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
1k views
Melting Point of Amorphous Solids [closed]
My textbook says that amorphous solids do not melt at a fixed temperature,but at a range of temperature. It depends on the way the atoms/molecules are present in a given piece of solid.
Since the ...
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0answers
29 views
Melting point of Ammonia at 143 psia
I'm currently working on a theory involving ammonia based life, but I need information about the freezing point of ammonia at high pressure to determine several ecological limitations at hand. I've ...
