For which of the following compounds is hydrogen bonding the main intermolecular force?
Question 19 options:
a) CS2
b) HCN
c) HBr
d) H2
e) H2O2
The answer is e) H2O2. Hydrogen bonding is the main intermolecular force in compounds that have a hydrogen atom bonded to an oxygen, nitrogen, or fluorine atom. H2O2 has two hydrogen atoms bonded to oxygen atoms, allowing for hydrogen bonding to occur between different molecules.
The main intermolecular force for a compound is determined by the presence of hydrogen bonding between its molecules. Hydrogen bonding occurs when hydrogen is bonded directly to a highly electronegative atom such as oxygen, nitrogen, or fluorine.
Among the options given, the compound that exhibits hydrogen bonding as the main intermolecular force is H2O2 (option e). This is because hydrogen peroxide (H2O2) contains hydrogen bonded to an oxygen atom, which is highly electronegative. Hydrogen bonding is responsible for the strong intermolecular forces in H2O2, giving it a relatively high boiling point and surface tension compared to the other compounds listed.
To determine which compound exhibits hydrogen bonding as the main intermolecular force, we need to consider the compounds' molecular structures.
Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) and is attracted to another electronegative atom in a neighboring molecule. This creates a relatively strong intermolecular force.
Let's go through each option and analyze the molecular structures to identify if hydrogen bonding is possible:
a) CS2 - Carbon disulfide does not have hydrogen atoms bonded to highly electronegative atoms. Therefore, it does not exhibit hydrogen bonding.
b) HCN - Hydrogen cyanide consists of a hydrogen atom bonded to a carbon atom, which is then bonded to a nitrogen atom. Since nitrogen is highly electronegative, hydrogen bonding can occur between the hydrogen atom in one molecule and the nitrogen atom in another molecule. So, hydrogen bonding is possible in HCN.
c) HBr - Hydrogen bromide consists of a hydrogen atom bonded to a bromine atom. Bromine is less electronegative than nitrogen or oxygen, so the hydrogen bonding in HBr is weaker compared to HCN. However, HBr can still exhibit hydrogen bonding to a lesser extent.
d) H2 - Hydrogen gas consists of two hydrogen atoms bonded together. Hydrogen bonding requires a hydrogen atom to be bonded to an electronegative atom other than itself, so hydrogen bonding is not possible in H2.
e) H2O2 - Hydrogen peroxide has two oxygen atoms bonded to hydrogen atoms, making it possible for hydrogen bonding to occur between the hydrogen atom and the oxygen atom in a neighboring molecule. Therefore, hydrogen bonding is possible in H2O2.
Based on our analysis, the compound that exhibits hydrogen bonding as the main intermolecular force is HCN (option b).