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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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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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.
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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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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 ...
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Melting and boiling point comparison

Graphite, silica and diamond are covalent compounds and still they have high melting and boiling points. Why?
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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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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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....
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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 ...
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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 ...
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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 ...
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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 ...
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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, ...
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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.
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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 ...
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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 ...
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Can you melt wood?

We talked about it in our chemistry class but we couldn't get to a conclusion, any help?
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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~^\...
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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 ...
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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 ...
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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 ...
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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,...
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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?
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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 $-...
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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.
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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 ...
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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{...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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Material that doesn't melt at 800 deg F, but can be dissolved?

I'm a sculptor and I have a chemistry/plastic question. I thought here would be a good place to ask. I'm looking for a substance (probably a plastic) that has these characteristics: Doesn't melt at ...
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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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The highest melting point

Inspired by this question, what is the substance or compound with the highest melting point? At standard atmospheric pressure and ever-increasing temperature which substance a) eventually becomes ...
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How to calculate which ionic compound has the highest melting point?

Which of the following compounds has the highest melting point: $\ce{PCl5}$, $\ce{H2O}$, $\ce{NaCl}$, $\ce{SrCl2}$, $\ce{CaF2}$? In general, ionic compounds will have higher boiling points than those ...
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Is melting of gold a physical property?

I read that melting of gold is a physical property, but I wonder if this is true. If we want to melt gold we will need to add heat, and once we add heat to gold to melt it, there must be a chemical ...
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How to calculate melting/boiling points at different pressures

I know water boils at below room temperature in a vacuum, and want to know if there's an equation to calculate the melting or boiling points of elements or compounds at a given pressure. How would I ...
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Will heating alumina (Al2O3) to its melting point yield pure Al?

My inorganic chemistry is at a basic level, so my question is, if I heat alumina ($\ce{Al2O3}$), to its melting point around 2000 C, will I wind up with pure Al? I think the oxygen will release from ...
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Avoiding snow melting with salt

I've been quite stunned during the last Winter Olympics in Sochi by the following fact. Temperatures were quite high, sometimes 10° Celsius, and the organizers had to do something to prevent the snow ...
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Addition of salt to ice

Salt is very commonly added to ice even at room temperature to prevent it from melting. Can anyone explain how does it really work?
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Why do the melting and boiling points of the noble gases increase when the atomic number increases?

What causes the melting and boiling points of noble gases to rise when the atomic number increases? What role do the valence electrons play in this?