Among NH3, H2O and HF, which would you expect to have highest magnitude of hydrogen bonding and why?

0 votes
427 views
asked Oct 10, 2017 in Chemistry by jisu zahaan (28,760 points) 26 374 808

Among NH3, H2O and HF, which would you expect to have highest magnitude of hydrogen bonding and why? 

1 Answer

0 votes
answered Oct 10, 2017 by sforrest072 (157,439 points) 60 409 935

The extent of hydrogen bonding depends upon electronegativity and the number of hydrogen atoms available for bonding. 

Among nitrogen, fluorine, and oxygen, the increasing order of their electronegativities are N < O < F. Hence, the expected order of the extent of hydrogen bonding is HF > H2O > NH3. But, the actual order is H2O > HF > NH3. 

Although fluorine is more electronegative than oxygen, the extent of hydrogen bonding is higher in water. There is a shortage of hydrogens in HF, whereas there are exactly the right numbers of hydrogens in water. As a result, only straight chain bonding takes place. 

On the other hand, oxygen forms a huge ring-like structure through its high ability of hydrogen bonding. 

In case of ammonia, the extent of hydrogen bonding is limited because nitrogen has only one lone pair. Therefore, it cannot satisfy all hydrogens. 

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

One Thought Forever

“There is a close connection between getting up in the world and getting up in the morning.“
– Anon
~~~*****~~~

...