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In chemistry, an electrolyte is a substance that conducts electric current by dissociating into positively and negatively charged particles called ions, which migrate toward and are discharged at the negative and positive terminals (cathode and anode, respectively) of an electric circuit.
Most soluble salts, acids, and bases that are dissolved in a polar solvent, such as water, fall into this category. When a substance dissolves, it splits into cations and anions, which are evenly distributed throughout the solvent. All the compounds that dissolve in water are not an electrolyte. Sugar, for example, dissolves quickly in water but remains in the form of molecules but not as ions in the water. Sugar is a nonelectrolyte substance. Water is a very weak electrolyte since it is ionized weakly.
When salt is dissolved in a solvent such as water, the constituent components dissociate due to thermodynamic interactions between the solvent and solute molecules, a process known as “solvation.” When table salt (sodium chloride, NaCl) is dissolved in water, the salt (a solid) dissociates into its component ions, as shown by the dissociation reaction.
Nonelectrolytes are those substances that do not ionize or convert into ions when dissolved in water.
NaCl (s) → Na+ (aq) + Cl- (aq)
The electrolytes are classified into two groups based on the degree of ionization:
- Strong electrolytes – Strong electrolytes are electrolytes that are almost completely dissociated into ions in solution.
- Strong acid- eg, HCl, HI, HBr
- Strong bases- eg, NaOH, KOH, LiOH
- Salts- eg NaCl, KBr
Unionized molecules (electrolytes) are present in such little quantities that they can be neglected. Furthermore, they have no relevance in the investigation of strong electrolyte ionization constants. Strong electrolyte ionization equations do not use double-headed arrows like weak electrolyte ionization equations.
HCl + H2O → H3O+ + Cl–
HNO3 + H2O → H3O+ + NO3–
- Weak electrolytes- When a current is passed through a substance, it does not dissociate entirely into ions.
- Weak acids- HF, H2CO3
- Weak bases- NH3
In a solution, the molecules of a weak electrolyte are in equilibrium with its ions. As a result, the equation involving the ionization of weak electrolytes is shown with double-headed arrows, indicating that the reaction is reversible, as in-
NH3 + H2O ⇌ NH4++ OH–
CH3COOH + H2O ⇌ H3O++ CH3COO–
Difference between strong and weak electrolytes
STRONG ELECTROLYTES | WEAK ELECTROLYTES |
Strong electrolytes are electrolytes that are entirely ionized. | Weak electrolytes are electrolytes that are partially ionized. |
They have a high conductivity of electricity. | They have a low conductivity of electricity. |
In solution or molten form, these electrolytes are totally ionized. As a result, these compounds only contain ions in a liquid or molten form. | In a solution or molten state, these chemicals are partly ionized. Ions and un-dissociated molecules are present in these electrolytes. |
At moderate quantities, strong electrolytes totally dissociate. | At moderate concentrations, weak electrolytes do not entirely dissociate. |
At high concentrations, there are strong interionic interactions. | Even at higher concentrations, interionic interactions are weak. |
Acids, alkalis, and salts like sodium chloride, potassium chloride, sodium hydroxide, potassium hydroxide, sodium nitrate, and lead sulfate, are all examples of strong electrolytes. | Acids, alkalis, and salts like oxalic acid, formic acid, acetic acid, ammonium hydroxide, calcium hydroxide are all examples of weak electrolytes. |
Ostwald’s dilution law is not applicable. | Ostwald’s dilution law is applicable. |
Physiological importance of electrolyte
Sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl), hydrogen phosphate (HPO42), and hydrogen carbonate (HCO3) are the major ions of electrolytes in physiology. The plus (+) and minus (-) electric charge symbols indicate that the substance is ionic in nature and has an unbalanced distribution of electrons as a result of chemical dissociation. Sodium is the most abundant electrolyte in extracellular fluid, and potassium is the most abundant electrolyte in intracellular fluid; both are important for fluid balance and blood pressure control.
Muscle tissue and neurons are both considered electric body tissues. Electrolyte interaction between the extracellular fluid (interstitial fluid) and intracellular fluid activates muscles and neurons. Ion channels specialized protein structures located in the plasma membrane that allow electrolytes to enter and exit the cell membrane. Calcium (Ca2+), sodium (Na+), and potassium (K+), for example, are required for muscular contraction. Muscular weakness or strong muscle spasms might develop if these important electrolytes are not present in sufficient amounts.
Conclusion-
Electrolytes are one of the most important components of electrochemical cells in science. Apart from this, they have a major role in the human body to maintain electrolyte balance for efficient functioning of the body.
