The key difference between salt bridge and hydrogen bond is that salt bridge is a tube with an electrolyte connecting two half cells in an electrochemical cell, whereas hydrogen bond is an attraction force between two atoms of two different molecules.
The salt bridge is very useful in maintaining the connectivity between two half cells of an electrochemical cell. It is visible to the naked eye. However, the hydrogen bond is a chemical bond that maintains the connectivity between two molecules, which can form hydrogen bonds.
CONTENTS
1. Overview and Key Difference
2. What is a Salt Bridge
3. What is a Hydrogen Bond
4. Side by Side Comparison – Salt Bridge vs Hydrogen Bond in Tabular Form
5. Summary
What is a Salt Bridge?
Salt bridge is a tube that contains an electrolyte (typically in the form of a gel), providing electrical contact between two solutions. Therefore, this tube is important in connecting oxidation and reduction reactions of the galvanic cell. The purpose of using a salt bridge is to facilitate the electrochemical reaction reaching the equilibrium quickly. If there is no salt bridge, then one half-cell will accumulate positive charges, and the other half cell accumulates negative charges. Consequently, the generation of electricity stops.
There are two main types of salt bridges: glass tube bridge and filter paper bridge. The glass tube salt bridge is a U-tube made of glass and it contains the electrolyte. In the filter paper salt bridge, there is a filter paper soaked with the electrolyte.
What is Hydrogen Bond?
A hydrogen bond is a type of attraction force between two atoms of two different molecules. It is a weak attraction force. But, when compared to other types of intramolecular forces such as polar-polar interactions, nonpolar-nonpolar interactions like Vander Waal forces, the hydrogen bond is stronger.
Usually, hydrogen bonds form between polar covalent molecules. These molecules contain polar covalent bonds, which form as a result of the difference in the electronegativity values of the atoms that are in the covalent bond. If this difference is high, the highly electronegative atom tends to attract the bond electrons towards itself. Thus, this creates a dipole moment where this highly electronegative atom gets a partial negative charge, whereas the other atom gets a partial positive charge. Then the bond becomes a polar covalent bond. When this molecule meets another molecule that has a dipole moment like this, the negative and positive charges tend to attract each other. And, this attraction force is called a hydrogen bond.
Moreover, hydrogen bonds are formed between highly electronegative atoms and less electronegative atoms. Further, they exist when we have O, N, and F in one molecule and positive charged H in the other molecule. It is because F, N, and O are the most electronegative atoms that are capable of forming hydrogen bonds.
What is the Difference Between Salt Bridge and Hydrogen Bond?
Salt bridge and hydrogen bond are important in mainlining connectivity between desired objects. For instance, a salt bridge connects two half cells of an electrochemical cell, while hydrogen bond connects two molecules. The key difference between salt bridge and hydrogen bond is that a salt bridge is a tube with an electrolyte connecting two half cells in an electrochemical cell. But, a hydrogen bond is an attraction force between two atoms of two different molecules.
Below infographic summarizes the difference between salt bridge and hydrogen bond.
Summary – Salt Bridge vs Hydrogen Bond
Salt bridge and hydrogen bond are important in maintaining connectivity between desired objects. For instance, the salt bridge connects two half cells of an electrochemical cell, while the hydrogen bond connects two molecules. The key difference between salt bridge and hydrogen bond is that a salt bridge is a tube consisting an electrolyte, and it connects two half cells in an electrochemical cell, whereas hydrogen bond is an attraction force between two atoms of two different molecules.
Reference:
1. Helmenstine, Anne Marie. “Salt Bridge Definition.” ThoughtCo, Jul. 3, 2019, Available here.
Image Courtesy:
1. “Galvanic Cell” By Gringer – File:Galvanische Zelle.png, by Tinux (CC BY-SA 3.0) via Commons Wikimedia
2. “Hydrogen-bonding-in-water-2D” (Public Domain) via Commons Wikimedia