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
0 votes
1 answer
48 views

Comparing melting point of neopentane and butanol

Why does something like 2,2-dimethylpropane have a much higher melting point than butan-1-ol? I know that butan-1-ol has a hydroxyl group, and is capable of hydrogen bonding, and I know that 2,2-...
1 vote
1 answer
40 views

How to calculate the freezing point of an equimolar ethanol: water mixture using colligative properties [closed]

I am familiar with how to calculate the freezing point of a mixture with a 9:1 molar ratio of ethanol to water (see below). I can understand that ethanol, having a higher mole fraction, is considered ...
4 votes
1 answer
175 views

Melting and boiling point of transition-metals, primarily for the groups of Cr and Mn [duplicate]

The NCERT Chemistry book for Grade 12 writes The high melting points of these metals are attributed to the involvement of greater number of electrons from $(n-1)d$ in addition to the ns electrons in ...
  • 99
0 votes
0 answers
37 views

Extent of Melting of Bonds or Intermolecular Forces

I'm currently having a revisit on the subject of periodicity of the periodic table, and I came across an issue that is kind of bugging me. If we take a look at the melting and boiling point trends of ...
2 votes
0 answers
47 views

Interpreting Ternary Phase Diagram Stoichiometry

I am trying to locate the lowest-melting mixture in a system of three nitrate salts: sodium, potassium, and calcium nitrate. I have the relevant ternary phase diagram, but I am unsure exactly about ...
15 votes
6 answers
5k views

What easily accessible material has melting point between 500 °C and 590 °C?

Is there an available at home material with the melting point between 500 °C and 590 °C? Plastics usually melt below 400 °C. Tin and lead also below that. Aluminum is melting above 600 °C. I made a ...
  • 301
2 votes
0 answers
51 views

What is the difference between milk and cream that causes disparate result when freezing and thawing?

If you freeze milk and then let it thaw/melt again you just need to shake and it is more or less indistinguishable from unfrozen milk. That is not true for cream - after letting frozen cream (40 % fat)...
  • 189
-1 votes
1 answer
60 views

lowest melting point of alkali salts [closed]

I want to make the alkali metals sodium and potassium through electrolysis of molten salts. However, I only have the ability to heat stuff up to about 260 degrees Celsius. What would be the lowest ...
-2 votes
1 answer
87 views

Boiling and melting points of hydrocarbons [closed]

What happens while boiling and melting hydrocarbons? Which bonds are broken? When we compare the boiling point (b.p.) and melting point (m.p.) of certain hydrocarbons the order is inverted. For ...
2 votes
0 answers
96 views

What happens to the sea of electrons when a metal melts/boils? [closed]

I was taught about metallic solids with the sea of electrons model. My question is how does the sea of electrons function when metal turns into a liquid and a gas. The way I see a liquid is ...
1 vote
1 answer
229 views

By how much does borax reduce the melting temperature of gold?

I'm researching ways in how to salvage gold from old electronics. I think I got the process down but I have one question. When you have salvaged the gold from the electronics you are left with gold ...
10 votes
3 answers
2k views

How can steel be so different from iron, even if amount of carbon is small?

Perhaps I am too naive, but I am having a hard time visualizing how even 'high-carbon' iron and steel alloys are maybe, at most, about four percent carbon by mass, which still means only one (smaller) ...
  • 1,659
4 votes
1 answer
110 views

Why does fcc lithium melt with increased pressure?

According to the phase diagram of lithium given here, the fcc phase formed at moderately high pressure melts at decreasing temperature upon adding more pressure, an effect better known with the ...
  • 42.2k
3 votes
1 answer
856 views

The melting and boiling point decreases down the group up to group 14 (not including transition metals), but the trend reverses from group 15. Why?

In groups 1, 2, 13 and 14, the melting and boiling point decreases down the group with a few exceptions. In group 15 the melting/boiling point increases up to Arsenic and then started decreasing. In ...
  • 297
3 votes
2 answers
239 views

Why is the thermal stability of calcium carbonate higher than that of magnesium carbonate even though lattice energy decreases down a group?

The difference in thermal stability of $\ce{CaCO3}$ and $\ce{MgCO3}$ can be explained using Fajans' rules, but why not using the lattice energy method? Why is the thermal stability of $\ce{CaCO3}$ ...
1 vote
1 answer
504 views

What are some of the lowest melting point glasses available out there?

I'm wondering about lead-free "glass solder" or any glass frit powder or paste that has a very low melting point (under 400 c). What products are available to the layman, where can I find ...
0 votes
0 answers
30 views

Why there is not a consistent pattern between the carbon chain length and the melting point of fatty acids? [duplicate]

I looked at the melting temperature of different saturated fatty acids and I expected to see that with a longer chain of carbon the melting point would be higher as after all the var der Waals ...
0 votes
1 answer
167 views

Methanol-water mix freezing points - clarify contradictory online data > 60% w/w?

Extending an exploration of windshield washer-fluid choices to freezing points of methanol-water mixes, all web-sources located agreed to within a couple of degrees from 0-60% w/w, yet above this ...
  • 129
6 votes
1 answer
151 views

Why is the melting point of magnesium nitride less than that of beryllium nitride?

Why is melting point of $\ce{Mg3N2}$ lower than that of $\ce{Be3N2}$ ? I have two reasonings: The lattice energy of $\ce{Be3N2}$ is higher than that of $\ce{Mg3N2}$ so accordingly the melting point ...
  • 1,359
2 votes
0 answers
88 views

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 ...
0 votes
0 answers
41 views

What happens if you superheat timber in a zero oxygen environment? [duplicate]

I was thinking to myself, what would happen if you were to put a lump of wood in a zero oxygen environment and superheat it? It couldn’t burn because fire needs fuel, heat and oxygen however because ...
  • 11
2 votes
1 answer
73 views

Compound with pressure sensitive melting point at moderate temperature and pressure

I'm in need for a compound with ideally all of the following properties: A melting point of 5 °C or less at 1 atmosphere (or slightly lower pressure) A melting point of 12 °C or more at less than 20 ...
1 vote
0 answers
71 views

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 ...
3 votes
0 answers
60 views

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 ...
  • 1,209
1 vote
1 answer
2k views

Melting points of benzoic and stearic acids

I wonder, why does benzoic acid have a higher melting point than stearic acid? Here is the data: Benzoic acid melting point = 122.3 °C Stearic acid melting point = 69.3 °C I do understand that organic ...
2 votes
1 answer
92 views

Judging orders in a series of compounds

My teacher frequently gives us questions where we have to arrange the given binary compounds on basis of their melting points or solubilities. He did give us some instructions in order to judge this ...
0 votes
0 answers
111 views

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 ...
  • 101
0 votes
1 answer
487 views

Why is melting point of Vanadium higher than Iron? [duplicate]

The iron is found to have four unpaired electrons while vanadium has 3 of them. we say the binding energy is directly proportional to number of unpaired electrons and hence number of metallic bonds ...
  • 107
7 votes
0 answers
87 views

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{^...
  • 213
0 votes
1 answer
227 views

Melting point of objects and food

What is the melting point of egg yolk? Well, generally, when we break an egg, the yolk is in liquid state. After we pour it on a pan, the egg starts to cook and it hardens. My question is, can an egg ...
's user avatar
2 votes
0 answers
64 views

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 ...
3 votes
1 answer
1k views

Can silicon dioxide melt at 20 °C?

Can $\ce{SiO2}$ melt at $\pu{20 ^\circ C}$? I have searched the web for $\ce{SiO2}$ phase diagram, but it seems to me that almost all the graph I can find have the temperature axis where the minimum ...
0 votes
1 answer
3k views

Can Aluminum Hydroxide (Al(OH)3) be heated to it's melting temperature before decomposing?

On the wikipedia page for aluminum hydroxide the listed melting point is 300 °C (572 °F), but in the same page it states that aluminum hydroxide decomposes at only 180 °C (356 °F). Can aluminum ...
1 vote
1 answer
690 views

Clausius–Clapeyron equation: shape of phase diagrams makes no sense

I am trying to model the melting point of a substance at varying pressures (ranging from very small to very very large). All I am trying to do is make an equation that relates melting temperature to ...
0 votes
1 answer
616 views

Melting point of crystalline solids

Why crystalline solids have sharp melting points but melting point of amorphous solids vary within a range? Is it because the interaction energy is equal between atoms of crystalline solids so they ...
  • 13
-1 votes
1 answer
1k views

How can we tell if a salt will melt or decompose?

Take $\rm NaCl$ for instance, a salt that will melt when it reaches its melting point, and compare it with $\rm NH_4NO_3$, a salt that doesn't melt, but instead decomposes to $\rm N_2O$ and $\rm H_2O$ ...
-1 votes
1 answer
136 views

Covalent Bonds and Ionic Bonds [duplicate]

Covalent bond is a strong bond compared to Ionic Bonds but Ionic Compounds have higher melting and boiling points then covalent compounds. Why?
0 votes
1 answer
98 views

Mechanistic explanation of salt lowering temperature of ice slush

As we all know, adding salt to ice water lowers its temperature. I've read plenty of system-level accounts of energy balances, enthalpies, vapor pressures, phase equilibria and freezing points—I ...
  • 248
1 vote
2 answers
768 views

Why does strength of bond matter if melting only affects the the intermolecular of the molecules

So as I've been told, when a substance melts, the actual bonds of the substance aren't broken, only the IMFs (inter-molecular forces). So why is it that metal groups decrease in melting points going ...
0 votes
2 answers
882 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 ...
2 votes
1 answer
2k views

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 ...
  • 1,959
2 votes
3 answers
965 views

melting and boiling ...really equilibrium? [closed]

Why are melting and boiling considered equilibrium processes even though the amount (concentration) of both phases keep changing i.e from solid to liquid and so on?
10 votes
2 answers
2k views

d-Menthol vs dl-menthol: Does an enantiomer and its racemic mixture have different melting points?

I am checking out Wikipedia and it shows a different melting point (m.p.) for l-menthol $(\pu{42 ^\circ C}$ to $\pu{45 ^\circ C})$ vs dl-menthol $(\pu{36 ^\circ C}$ to $\pu{38 ^\circ C}).$ How is ...
  • 1,508
0 votes
0 answers
456 views

Why does ammonia have higher melting point but lower boiling point than HF? [duplicate]

I guess the reason is hydrogen bonding, but shouldn't both the trends be similar in that case?
  • 145
2 votes
1 answer
174 views

Does equality of molarity or molality determine constancy of boiling (or freezing) points of different solutions?

I encountered a question among papers for JEE (2005) that demands completing a statement: Equimolar solutions in the same solvent have _______ There are four options and the correct answers are ...
's user avatar
1 vote
1 answer
123 views

Pure gallium with lower melting point?

I melted about 2 kg of gallium and put it in a plastic container, in order to make crystals. After letting them grow and extracting them, I let the gallium freeze at the room temperature, which is ...
0 votes
1 answer
194 views

Why does roasting requires lower temperature than melting point

Why do processes like roasting and calcination require a temperature lower than the melting point? Since intermolecular forces are lower in a liquid won't it be easier to oxidise (roasting) / ...
2 votes
1 answer
755 views

How do scientists study liquid tungsten? [duplicate]

Inspired by this What If article: https://what-if.xkcd.com/50/ In the above article, Randall Munroe mentions that liquid tungsten is difficult to study because of its extremely high melting point. ...
  • 123
1 vote
1 answer
743 views

Freezing point vs Intermolecular forces

Water has a higher boiling point (100°C) than cyclohexane (81°C). This is probably because of stronger intermolecular forces between water molecules as compared to cyclohexane molecules. Then, why is ...
0 votes
0 answers
511 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 ...

1
2 3 4 5