Can you melt chemicals without changing their properties? (i.e Sugar can be melted and still be sugar.)?

Question

And how do you know what temperature changes the properties of specific chemicals?

Answer 1

Yes, melting does not alter the chemical nature of the material, it just changes the physical state (solid ---> liquid). For instance, if you heat sodium chloride (common table salt) to 800.7°C, it will melt. If you took that molten salt, and cooled it down, it would recrystallize. But the chemical nature of the sodium chloride would not have changed, though it might not be in the same fine crystals as when you started.

However, there are some materials that will decompose upon heating, before reaching their melting point.

You can look up the melting points of most chemicals in standard reference manuals such as the CRC Handbook of Chemistry & Physics, the Merck Index, in Material Safety Data Sheets, and in a variety of online references. They will also list the information if the compound decomposes before melting or boiling.

Answer 2

Your question really has two parts. In the first part, yes, a substance can be melted without changing its properties, but bear in mind that a substance has different properties in its liquid form than it does as a solid. However, melting is a reversible process; you can freeze the substance to regain a solid with the same properties it had before. In the second part, though, sugar is rarely melted. When sugar is heated in a cooking environment, it caramelizes, which is an oxidation reaction with air. So the sugar doesn't just melt; it undergoes a chemical reaction where it forms a different substance in the liquid phase. After it hardens, it has different properties than sugar does.

Answer 3

Melting is a physical process. Any chemical can be melted, under the right conditions.

At higher temperatures, reactions are more likely to occur.

Answer 4

Sugar is still sugar when it is melted. Melting is a physical change, not a chemical change. BURNING sugar is a chemical change. CO2 and H2O are two byproducts of combustion of organic materials such as glucose.

Answer 5

sugar is a crystal, so it doesn't really melt easily. when you heat it up it carmelizes,then burns. those are both chemical changes. however, under the perfect balance of heat and/or pressure, it can be done.

Answer 6

However, sugar could be melted in the absence of oxygen, as can many other substances which would otherwise oxidize, either rapidly (burn) or more slowly.