Electrolytes play a central role in solution chemistry, electrochemistry, biochemistry, and many industrial processes. In IB Chemistry, understanding what an electrolyte does helps you master topics like conductivity, electrolysis, redox reactions, and acid–base behavior. This article explains the function of an electrolyte clearly and shows how it fits into the broader framework of chemical principles.
What Is an Electrolyte?
An electrolyte is a substance that produces ions when dissolved in water, allowing the solution to conduct electricity.
The key idea is that electrolytes dissociate into mobile charged particles (cations and anions).
These ions enable the flow of electric current through a solution.
Examples of electrolytes:
- Sodium chloride (NaCl)
- Hydrochloric acid (HCl)
- Potassium hydroxide (KOH)
- Magnesium sulfate (MgSO₄)
When these substances dissolve, they break apart into ions.
How Electrolytes Conduct Electricity
Electricity in solutions is carried by the movement of ions.
Cations
- Positively charged
- Move toward the cathode (negative electrode)
Anions
- Negatively charged
- Move toward the anode (positive electrode)
Because the ions move in opposite directions, an electric current can pass through the solution.
The greater the number of ions, the higher the conductivity.
This is why electrolyte concentration strongly influences electrical conductivity.
Strong vs. Weak Electrolytes
In IB Chemistry, electrolytes are categorized by their degree of ionization.
Strong Electrolytes
- Completely dissociate in water
- Produce many ions
- Conduct electricity very well
Examples:
- Strong acids (HCl, HNO₃, H₂SO₄)
- Strong bases (NaOH, KOH)
- Soluble ionic salts (NaCl, KBr)
Weak Electrolytes
- Partially dissociate
- Produce fewer ions
- Conduct weakly
Examples:
- Weak acids (CH₃COOH)
- Weak bases (NH₃)
The degree of ionization is essential for understanding pH, equilibrium, and conductivity.
What Electrolytes Do in Chemical Systems
Electrolytes serve several important functions depending on the context.
1. Conduct Electricity in Solution
This is the primary function.
Electrolyte solutions conduct electricity because ions carry charge through the liquid.
Pure water conducts electricity very poorly because it contains very few ions.
2. Enable Electrolysis
Electrolysis requires:
- A conducting solution
- Movement of ions
- Redox reactions at electrodes
Without electrolytes, electrolysis cannot occur because no charged particles are available to transport electrons through the solution.
3. Allow Redox Reactions to Occur in Electrochemical Cells
In galvanic (voltaic) and electrolytic cells, electrolytes:
- Provide ions that carry charge
- Complete the internal circuit
- Balance charges as electrons move through the external wire
This prevents charge buildup and keeps the reaction running.
4. Support Acid–Base Chemistry
Acids and bases are electrolytes because they form ions:
- Acids form H⁺ (or H₃O⁺) ions
- Bases form OH⁻ ions
Their strength depends on how completely they ionize.
5. Maintain Ionic Balance
In many chemical and biological systems, electrolytes help maintain charge neutrality and stabilize reactions.
This concept is especially important in biochemistry, although IB Chemistry focuses primarily on the physical chemistry aspects.
Conductivity and Concentration
Conductivity depends on:
- The number of ions present
- The charge of the ions
- The mobility of ions
- The degree of dissociation
Higher concentration → more ions → greater conductivity
However, extremely high concentrations can reduce mobility due to ion crowding.
FAQs
Do all ionic compounds act as electrolytes?
Only soluble ionic compounds act as electrolytes. Insoluble salts do not dissolve, so they do not produce ions in solution.
Why doesn’t sugar conduct electricity?
Sugar dissolves but does not form ions. Because it remains as neutral molecules, it cannot conduct electricity.
Why is pure water a poor conductor?
Pure water contains almost no ions—only about 1 in 10 million molecules ionizes. Adding electrolytes greatly increases conductivity.
Conclusion
An electrolyte functions by producing ions that allow a solution to conduct electricity. These ions enable electrolysis, redox processes, acid–base reactions, and the operation of electrochemical cells. Understanding electrolytes is essential for mastering conductivity, equilibrium, titration, and electrochemistry in IB Chemistry.
