Grade 12 Chemistry
For which of the following compounds is hydrogen bonding the main intermolecular force?
Question 29 options:
a) BH3
b) CH4
C) HCN
d) CH2F2
e) CH3NH3
Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom (such as nitrogen, oxygen, or fluorine) and is attracted to another electronegative atom in a neighboring molecule.
Out of the options given, the main intermolecular force of hydrogen bonding would occur in compound e) CH3NH3. In this compound, the hydrogen atom is bonded to a highly electronegative nitrogen atom and can form hydrogen bonds with neighboring NH3 molecules.
To determine which of the compounds has hydrogen bonding as the main intermolecular force, we need to understand what hydrogen bonding is.
Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an electronegative atom (such as nitrogen, oxygen, or fluorine) and also attracted to the lone pairs of electrons on another electronegative atom in a different molecule. This results in a strong, directional force that can significantly affect the properties of a substance.
Let's analyze each compound to see if it has the potential for hydrogen bonding:
a) BH3: Boron does not have a significant electronegativity and cannot form hydrogen bonding.
b) CH4: Carbon is not highly electronegative, and there are no electronegative atoms bonded directly to the hydrogen atoms. Hence, CH4 does not undergo hydrogen bonding.
c) HCN: Carbon and nitrogen are both electronegative. Hydrogen bonding can occur between the partially positive hydrogen atom in one HCN molecule and the electronegative nitrogen atom in another HCN molecule. Therefore, HCN has the potential for hydrogen bonding.
d) CH2F2: Although fluorine is highly electronegative, there is not enough difference in electronegativity between carbon and hydrogen to form significant hydrogen bonding in CH2F2.
e) CH3NH3: Nitrogen is highly electronegative, and the lone pair of electrons on nitrogen can form hydrogen bonds with the hydrogen atoms in neighboring CH3NH3 molecules. Thus, CH3NH3 can undergo hydrogen bonding.
Therefore, the compound that has hydrogen bonding as the main intermolecular force is option C) HCN and option e) CH3NH3.
The main intermolecular force in a compound is determined by its ability to form hydrogen bonds. Hydrogen bonding occurs when hydrogen is bonded to highly electronegative elements such as nitrogen, oxygen, or fluorine.
Looking at the options provided:
a) BH3 - this compound does not contain any hydrogen atoms bonded to nitrogen, oxygen, or fluorine, so it does not exhibit hydrogen bonding.
b) CH4 - this compound does not contain any highly electronegative elements, so it does not exhibit hydrogen bonding.
c) HCN - this compound contains a hydrogen atom bonded to nitrogen, which is a highly electronegative element. Therefore, hydrogen bonding is possible in HCN.
d) CH2F2 - this compound does not contain any hydrogen atoms bonded to nitrogen, oxygen, or fluorine, so it does not exhibit hydrogen bonding.
e) CH3NH3 - this compound contains a hydrogen atom bonded to nitrogen, which is a highly electronegative element. Therefore, hydrogen bonding is possible in CH3NH3.
Based on the given options, the compounds that exhibit hydrogen bonding as the main intermolecular force are C) HCN and e) CH3NH3.