Higher melting point, PH3 or NH3?

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SUMMARY

The discussion centers on determining the compound with the highest melting point among three pairs: H2O vs. H2S, KBr vs. CF4, and NH3 vs. PH3. It is established that H2O has a higher melting point than H2S due to stronger hydrogen bonding. KBr exhibits a higher melting point than CF4 due to its ionic bonding characteristics. In the case of NH3 and PH3, the stronger hydrogen bonding in ammonia results in a higher melting point compared to phosphine, despite both having similar electronic configurations.

PREREQUISITES
  • Understanding of hydrogen bonding and its effects on melting points
  • Knowledge of ionic vs. covalent bonding
  • Familiarity with electronegativity and its role in bond strength
  • Basic concepts of molecular geometry and intermolecular forces
NEXT STEPS
  • Research the properties of hydrogen bonding in ammonia (NH3)
  • Study the differences between ionic and covalent compounds, focusing on KBr and CF4
  • Explore the concept of electronegativity and its impact on molecular interactions
  • Investigate the melting points of various compounds and the factors influencing them
USEFUL FOR

Chemistry students, educators, and professionals interested in understanding the factors affecting melting points and intermolecular forces in compounds.

ANDR3W
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Hi everyone, I have a question for all of you

In an exercise of chemistry it's written to find the compound, between every couple, which has the highest melting point.

The three couples are: H20 H2S; KBr CF4, NH3 PH3.

In the first case water has higher melting point because the bond is stronger than the sulfuric acid one.
In the second case, looking at the electronic configuration, we can spot that Br has 4p5 and so makes an ionic bond with K that is giving away its electron to complete valence shell.

In the third case i really don't know what to think.
They have same electronic configuration so i don't know how to spot the higher one..
Can anybody help me? :)
Thank you.
 
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ANDR3W said:
Hi everyone, I have a question for all of you

In an exercise of chemistry it's written to find the compound, between every couple, which has the highest melting point.

The three couples are: H20 H2S; KBr CF4, NH3 PH3.

In the first case water has higher melting point because the bond is stronger than the sulfuric acid one.
In the second case, looking at the electronic configuration, we can spot that Br has 4p5 and so makes an ionic bond with K that is giving away its electron to complete valence shell.

In the third case i really don't know what to think.
They have same electronic configuration so i don't know how to spot the higher one..
Can anybody help me? :)
Thank you.

Well, what are the dominant intermolecular forces between ammonia molecules? Do you expect those to be stronger or weaker than the forces between phospine molecules? Is there any similarity between this pair and the other pairs you considered?
 
H2S is not sulfuric acid. H2S is hydrogen sulfide.
 
Look at the Electronegativity
 

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