# Homework Help: Which substance exhibits the most hydrogen bonding?

1. Mar 13, 2012

### Bipolarity

1. The problem statement, all variables and given/known data

Which of the following substances exhibits significant hydrogen bonding in the liquid state?

A) $CH_{2}F_{2}$
B) $N_{2}H_{4}$
C) $CH_{3}OCH_{3}$
D) $C_{2}H_{4}$
E) $C_{2}H_{2}$

2. Relevant equations

3. The attempt at a solution

I know that hydrogen bonding generally only works with hydrogen being attracted to a nonbonding pair on a very electronegative atom (N,F,O and Cl). So only A,B, and C can be the answer. The answer turns out to be B, but I really thought it would be A since flourine is the most electronegative.

I also don't understand whether being in the liquid state has any bearing on the problem.

BiP

2. Mar 13, 2012

### Ygggdrasil

In a hydrogen bond, you must have a hydrogen bond donor and a hydrogen bond acceptor. The donor requires a hydrogen covalently bound to either a fluorine, nitrogen or oxygen. The hydrogen bond acceptor requires a lone pair on a fluorine, nitrogen or oxygen.

Compound A is capable of acting as a hydrogen bond acceptor, but because the hydrogens are bound to the carbon, it is incapable of acting as a hydrogen bond donor.