Q. 45.0( 4 Votes )
Hydrogen bonds are formed in many compounds e.g., H2O, HF, NH3 . The boiling point of such compounds depends to a large extent on the strength of hydrogen bond and the number of hydrogen bonds. The correct decreasing order of the boiling points of above compounds is :
A. HF > H2 O > NH3
B. H2O > HF > NH3
C. NH3 > HF > H2 O
D. NH3 > H2O > HF
The strength of H-bonding depends on the electronegativity of the atom which follows the order: F > O > N.
Thus, the strength of bonding will be in the following order:
H……. F > H…….O > H…….. N
The H2O molecule is linked to 4 other H2O molecules through H-bonds whereas each HF molecule is linked only to two other HF molecules.
Thus, the H2O molecules bonding will be stronger than HF bonding.
Hence, correct decreasing order of the boiling points is H2O > HF > NH3
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