Textbook Question
Use the phase diagram of neon to answer the following questions. (b) What can you say about the strength of the intermolecular forces in neon and argon based on the critical points of Ne and Ar (see Table 11.5.)?
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Ch.11 - Liquids and Intermolecular Forces
Chapter 11, Problem 66
What observations made by Reinitzer on cholesteryl benzoate suggested that this substance possesses a liquid crystalline phase?
Verified step by step guidance1
Step 1: Understand the context of the problem by recognizing that cholesteryl benzoate is a compound that was studied for its unique phase behavior, which led to the discovery of liquid crystals.
Step 2: Note that Reinitzer observed cholesteryl benzoate under different temperature conditions to study its phase transitions.
Step 3: Identify that Reinitzer observed two distinct melting points for cholesteryl benzoate, which was unusual for a pure compound.
Step 4: Recognize that the first melting point indicated a transition from a solid to a cloudy liquid, suggesting an intermediate phase between solid and liquid.
Step 5: Understand that the second melting point indicated a transition from the cloudy liquid to a clear liquid, confirming the presence of a liquid crystalline phase.
Related Practice
Textbook Question
At 25 °C gallium is a solid with a density of 5.91 g/cm3. Its melting point, 29.8 °C, is low enough that you can melt it by holding it in your hand. The density of liquid gallium just above the melting point is 6.1 g/cm3. Based on this information, what unusual feature would you expect to find in the phase diagram of gallium?
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Open Question
In terms of the arrangement and freedom of motion of the molecules, how are the nematic liquid crystalline phase and an ordinary liquid phase similar? How are they different?
Textbook Question
Indicate whether each statement is true or false: (c) Molecules that exhibit a liquid crystalline phase do so at well-defined temperatures and pressures.
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Textbook Question
For a given substance, the liquid crystalline phase tends to be more viscous than the liquid phase. Why?
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Open Question
It often happens that a substance possessing a smectic liquid crystalline phase just above the melting point passes into a nematic liquid crystalline phase at a higher temperature. Account for this type of behavior.