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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 point vs Freezing point

Is it possible to have Melting point different that Freezing point I mean is there any element/molecule in the liquid status that freeze at point X Centigrade but when it become solid then you need a ...
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Why does the temperature remain constant during freezing?

I know it's the most silly question one could ever ask but why is that so? I am aware of what latent heat means and I also know it has something to do with freezing too. Say I have with me, a mug of ...
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How does addition of impurities in a solid decrease the melting point? [duplicate]

In my textbook, it is written: The addition of impurities in a solid decreases the melting point of the solid. How does it do so? Why can't it increase the melting point?
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Why Cu has higher melting point than Ag and Au?

Actual trend in transition metal is M.P. of 5d series > M.P. of 4d series> M.P. of 3d series. But I don't understand why there is an anomaly in the case of 11 the group.
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Comaparing melting points of group 14 elements [duplicate]

I found that melting point of $\ce{Sn(232°C)}$ is less than $\ce {Pb (327.5°C)} $ but i also saw that the bond enthalpy of $\ce {Sn-Sn(187.1 ±0.3 kJ mol^{-1})}$ is more than $\ce{Pb-Pb 86.6 ±0.8 kJ ...
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Boiling points and melting points of nitrogen and oxygen

Why does nitrogen have a higher melting point, but a lower boiling point than oxygen? I have been taught that nitrogen has a higher melting point as it has a larger molecular size, but doesn't ...
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Melting of ionic compound hydrates

My professor asked us the reason of the melting point of potash alum being so low, despite it being an ionic salt. He later went on to answer it by saying that melting point is a misnomer for the ...
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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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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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163 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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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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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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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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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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271 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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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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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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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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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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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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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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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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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 ...
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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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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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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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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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141 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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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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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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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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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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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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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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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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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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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 ...
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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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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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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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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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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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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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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?
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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 ...
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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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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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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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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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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 ...