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Introduction
Electrolytes can be defined as any substance that breaks down into positively and negatively charged particles called ions when dissolved in water. These charged particles help conduct an electric current, and the quantity in which they are dissociated is the critical criteria for categorizing a solution. If a compound’s dissociation is high, it is called strong electrolyte. If the extent of dissociation is low, the electrolyte is called weak. This categorization is essential as it decides the intensity with which an electrolyte can conduct electricity.
Electrolytes may dissociate into a solution entirely or partially, which determines their ability to conduct electricity. The dissociation breaks down the dissolved substance into positively charged ions called cations or negatively charged ions called anions. The number of these ions in the aqueous solution is the deciding factor for classifying the compound into weak or strong electrolyte.
The critical thing to note here is that the concentration of ions is only one of the three critical factors that impact the electrical conductivity of electrolytes. The other two decisive factors are as follows.
- The electrolyte’s chemical nature, whether it is a strong acid or base, weak acid or base, or even salt breaks, which, in turn, determines the extent of ionization of the substance.
- The temperature at which the electrolyte is dissolved in the solvent impacts its solubility, which affects the overall electrolyte level of ionization.
Strong electrolyte
Substances that dissociate entirely upon being dissolved in water are known as strong electrolytes. This means that the solution contains only ions and has zero molecules of the dissolved substance. The electrolytes can conduct a large amount of electricity and hence are good conductors of electricity. However, they exhibit this property only when they are in the form of aqueous solutions or when they are in molten form.
The ionization of a solute in the solvent in the case of a strong electrolyte can be expressed with the help of the following general chemical equation.
strong electrolyte (aq) → cation+ (aq) + anion- (aq)
A strong electrolyte can be classified into strong acids, strong bases, and salts based on whether the substance dissolved is an acid, a base, or a salt. Some examples of a strong electrolyte for each category are given below.
Strong Acid: HCl, HNO3, HClO3, HClO4, and H2SO4
Strong Bases: NaOH, KOH, LiOH, Ba(OH)2, and Ca(OH)2
Salts: NaCl, KBr, and MgCl2
Weak electrolyte
When the molecules of an electrolyte dissociate only partially in water by a ratio of (1-10%), it results in the formation of a weak electrolyte. The concentration of charged ions in the solutions thus formed is less, while the electrolyte molecules are present in large numbers. Few charged ions in weak electrolytes allow only minimal electricity to flow. This naturally makes weak electrolytes are poor conductors of electricity.
These electrolytes are classified into weak acids and weak bases based on the type of substance. Salts do not generally form weak electrolytes as they almost always undergo 100% ionization when they are dissolved in water. Some examples of the two main types of weak electrolytes are given below.
Weak Acids: HF, H2CO3, H3PO4 etc.
Weak Bases: NH3, C5H5N etc.
Differences Between strong electrolyte and weak electrolyte
Understanding the differences between strong and weak electrolytes can help to gain a better understanding of both of these types of substances. Below is a table comparing the distinctive properties of a strong electrolyte and weak electrolyte compared to each other.
Strong Electrolytes | Weak Electrolytes |
These electrolytes dissociate entirely upon being dissolved in water, resulting in 100% cations and anions. | These electrolytes dissociate only partially upon being dissolved in water, resulting in a relatively small number of cations and anions. |
Given the complete dissociation of the electrolyte, no molecules of the same are present in the solution. | The partial dissociation of the electrolyte ensures that a significant number of molecules of the same are still a part of the resulting solution. |
The high concentration of charged ions makes them good conductors of electricity. | The low concentration of charged ions ensures that these electrolytes are poor conductors of electricity. |
The conductance of these electrolytes increases slightly with an increase in the dilution of the solution. | The conductance of these electrolytes increases rapidly with an increase in the dilution, especially when the solution reaches near-infinite dilution. |
These electrolytes experience strong interionic interactions at moderate concentrations. | The interionic interactions in these electrolytes are not strong even at higher concentrations. |
Conclusion
Electrolysis is an integral part of many industrial processes, and electrolytes play an essential role in ensuring the success and efficiency of these processes. Having proper knowledge about strong and weak electrolytes makes it easier to choose the proper substances to be used as the perfect electrolytes in different cases. Contrary to popular belief, it is not the vital electrolytes that are helpful in various situations, as sometimes weak electrolytes may also be required in specific scenarios. Knowing the difference between these two electrolytes is essential to ensure their proper use and get the desired results with minimum error.
