Melting and boiling points of titanium tetrahalides

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Discussion Overview

The discussion revolves around the melting and boiling points of titanium tetrahalides (TiF4, TiCl4, TiBr4, TiI4) and the implications of these properties on the bonding nature (ionic vs. covalent) of these compounds. Participants explore how to rationalize the data in terms of bonding and intermolecular forces, while also addressing potential discrepancies in the provided information.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant questions how to determine the ionic or covalent nature of TiF4 compared to TiCl4, TiBr4, and TiI4 without prior knowledge.
  • Another participant notes the unusual observation of compounds with higher melting points than boiling points, suggesting a possible error in the table's column titles.
  • There is a discussion about the general rules of boiling and melting points for ionic versus covalent compounds, with some participants asserting that ionic compounds typically have higher melting and boiling points.
  • A participant asks if there is a specific melting point or boiling point value that defines whether a compound is considered ionic, to which others respond that no definitive temperature exists due to the mixed nature of bonding in compounds.
  • One participant points out that the data should be compared within a series of analogous compounds to identify anomalies.

Areas of Agreement / Disagreement

Participants express differing views on the classification of the compounds based on their melting and boiling points, and there is no consensus on whether the column titles in the table are correct. The discussion remains unresolved regarding the implications of the data on the bonding nature of the compounds.

Contextual Notes

Some participants reference external sources that provide different melting point values for TiF4, indicating potential discrepancies in the data presented. The discussion also highlights the complexity of defining ionic versus covalent character based on melting and boiling points alone.

i_love_science
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Homework Statement
The melting and boiling points of the titanium tetra- halides are given in the table (see below). Rationalize these data in terms of the bonding in and the intermolecular forces among these compounds.
Relevant Equations
bonding
intermolecular forces
Table
boiling point (°C)melting point (°C)
TiF4284N/A
TiCl4-24136.5
TiBr438233.5
TiI4155377

The solution says that TiF4 is an ionic compound, while TiCl4, TiBr4, and TiI4 are covalent compounds. How would I determine this from the problem without prior memorization/knowledge? Thanks.
 
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What do you know about general rules of boiling/melting points of ionic and covalent compounds?
 
i_love_science said:
Table
boiling point (°C)melting point (°C)
TiF4284N/A
TiCl4-24136.5
TiBr438233.5
TiI4155377

We all have something to learn, and I had never met before compounds whose melting points were higher than their boiling points, have I missed something?
 
epenguin said:
We all have something to learn, and I had never met before compounds whose melting points were higher than their boiling points, have I missed something?
It would appear that the column titles are switched.

i_love_science said:
Homework Statement:: The melting and boiling points of the titanium tetra-halides are given in the table (see below). Rationalize these data in terms of the bonding in and the intermolecular forces among these compounds.
Relevant Equations:: bonding
intermolecular forces

Table
boiling point (°C)melting point (°C)TiF4284N/ATiCl4-24136.5TiBr438233.5TiI4155377
Check the information in the Table. Various sources, including supplier websites, have the melting point of Ti(IV)fluoride as 377° C (710.6° F), and it sublimes.
https://www.americanelements.com/titanium-iv-fluoride-7783-63-3
https://www.americanelements.com/titanium-iv-iodide-7720-83-4
 
Last edited:
Borek said:
What do you know about general rules of boiling/melting points of ionic and covalent compounds?
Ionic compounds have higher boiling and melting points than covalent compounds. Is there a specific mp or bp value above which compounds are considered ionic?

Astronuc said:
It would appear that the column titles are switched.
They're actually not switched, this is the exact question.
 
i_love_science said:
Ionic compounds have higher boiling and melting points than covalent compounds.

OK

Is there a specific mp or bp value above which compounds are considered ionic?

No, but as the rule is only approximate there is no way to define such temperatures (plus, there are no such things as purely ionic or purely covalent compounds, each bond has some mixed properties). However, it works quite well when you have a series of analogous compounds that can be easily compared. That's the case here, do you see any anomaly in the data?
 

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