I can't figure out why this happens with pure substances. My book is a

In summary, the conversation discusses the confusion surrounding the behavior of pure substances, specifically water, below triple-point pressures. The individual has found their book to be unhelpful and is seeking recommendations for a better resource. They pose a question about the sublimation of water and how it relates to enthalpy and energy added to the solid state. They also mention the lack of information on this subject from Wikipedia and express frustration with the complexity of the topic.
  • #1
Curl
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I can't figure out why this happens with pure substances. My book is a piece of junk, perhaps someone could recommend a better book.

But why does water, for example, sublime below triple-point pressures?

If I'm below triple point pressure and I add energy to solid water, there should be a point where I can break the crystal bonds. But I just added enough energy to pay for the "latent heat" of fusion, not nearly enough for the enthlapy of vaporization.

So what happens? Does it remain a solid? How does that work, what happens to the energy I added? I don't see why the liquid phase is skipped.

Thanks for any help.
P.S. Wikipedia is worthless on this subject.
 
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  • #2


Wow, honestly I didn't think this was such a tough question...
 
  • #3


As far as enthalpies of fusion and vaporization, they're different for different temps and pressures, so I'm sure that the calculations go right if you use the enthalpies of the below-triple-point pressure and not the STP enthalpies.
 

FAQ: I can't figure out why this happens with pure substances. My book is a

1. Why do pure substances have different properties?

Pure substances can have different properties because they are made up of different combinations of elements. Each element has its own unique properties, and when they are combined in different ways, they can result in different properties for the pure substance.

2. What are some examples of pure substances?

Some examples of pure substances include water, sugar, salt, oxygen, and gold. These substances are made up of only one type of element or compound and have a uniform composition throughout.

3. How are pure substances different from mixtures?

Pure substances are different from mixtures because they have a definite and constant composition, while mixtures can have varying compositions. Pure substances also have uniform properties throughout, while mixtures can have different properties in different parts of the mixture.

4. How can I determine the properties of a pure substance?

The properties of a pure substance can be determined through various methods such as physical and chemical tests, as well as using scientific instruments. These tests can help identify the physical and chemical properties of the substance, such as melting point, boiling point, density, and reactivity.

5. Can pure substances exist in nature?

Yes, pure substances can exist in nature. For example, elements such as gold and silver can be found in their pure form, and compounds such as water and carbon dioxide can also exist as pure substances in nature. However, pure substances may also be produced through chemical reactions and laboratory processes.

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