Chemistry Melting and boiling points of titanium tetrahalides

AI Thread Summary
The discussion focuses on the melting and boiling points of titanium tetrahalides, highlighting that TiF4 is an ionic compound while TiCl4, TiBr4, and TiI4 are covalent. It raises questions about how to determine the nature of these compounds without prior knowledge and discusses the general rules regarding the boiling and melting points of ionic versus covalent compounds. Participants note an anomaly where some compounds have higher melting points than boiling points, leading to confusion about the data presentation. The conversation concludes that while ionic compounds typically exhibit higher melting and boiling points, there are no strict temperature thresholds to classify compounds as ionic or covalent. Understanding these properties is essential for analyzing the bonding and intermolecular forces in these compounds.
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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