Answer to Question #233043 in Physical Chemistry for Uswa

Question

How many hydrogen bonds a water molecule can form with another water molecule?
Kindly give explanation too

Answer 1

Hydrogen bonds are attractive forces that are formed between hydrogen atom of one molecule and a very electronegative atom (N, O or F) of other molecule. However, for hydrogen atom to be able to participate in H-bonding, it must be also bonded to an electronegative atom (N, O or F). Hydrogen atoms that satisfy this rule are called hydrogen bond donors, while an electronegative atoms of other molecule are called hydrogen bond acceptors. One hydrogen can be a donor for one hydrogen bond only. An acceptor, in its turn, can form the number of hydrogen bonds that is equal to the number of lone pairs on it.

In case of water, there are 2 hydrogen atoms bonded to O, hence they are eligible for hydrogen bonding. Oxygen atom has 2 lone pairs on it, hence it can accept 2 hydrogen bonds from other molecules. So there are maximum of 4 bonds that one water molecule can form (with 4 surrounding molecules).

However, this question is about another SINGLE molecule, and assuming that there is a system of two molecules only, the answer is 1.

The simple scheme of hydrogen bond formation by one (central) water molecule is below. Hydrogen bonds are shown in blue. It is obvious that there is only one bond between it and any other molecule.

Answer: 1