Difference Between Strong and Weak Electrolytes

Main Difference – Strong vs Weak Electrolytes

Electrolytes are substances that give ions when dissolved in water. The three main types of electrolytes are acids, bases and salts and these compounds are dissociated into ions when dissolved in water. The positively charged and negatively charged ions can conduct electricity through an aqueous solution of these compounds. Some electrolytes are strong compounds and others are weak electrolytes. The main difference between strong electrolytes and weak electrolytes is that strong electrolytes can almost completely dissociate into its ions whereas weak electrolytes partially dissociate into ions.

Key Areas Covered

1. What are Strong Electrolytes
      – Definition, Properties, Reactions
2. What are Weak Electrolytes
      – Definition, Properties, Reactions
3. What is the Difference Between Strong and Weak Electrolytes
      – Comparison of Key Differences

Key Terms: Acids, Bases, Electrolytes, Salts, Strong Electrolytes, Weak Electrolytes

What are Strong Electrolytes

A strong electrolyte is a compound that can completely dissociate into its ions when dissolved in water. Therefore, a strong electrolyte is a solute that completely dissolves in water. An electrolyte is composed of cations or positively charged ions and anions or negatively charged ions. These ions can conduct an electric current in a solution.

Figure 1: Strong Acids and Strong Bases are Strong Electrolytes

Common strong electrolytes are strong acids, strong bases, and ionic salts. However, some electrolytes do not completely dissolve in water but are considered as strong electrolytes. This is because the amount that is dissolved is completely ionized into its ions.

For example, strong acids such as HCl, HNO₃ are strong electrolytes. These are dissociated into their cation H⁺ and the anion completely. Strong bases such as NaOH completely dissociates into ions that can conduct electricity.

What are Weak Electrolytes

Weak electrolytes are compounds that partially dissociate into its ions when dissolved in water. Weak electrolytes are composed of cations and anions. The ionic character of these compounds is less when compared with strong electrolytes. Common weak electrolytes are weak acids, weak bases, and salts.

Usually, around 1-10% of the compound is dissociated into ions. Most nitrogen-containing compounds are weak electrolytes. Water is also considered as a weak electrolyte since water molecules are partially dissociated into H⁺ and OH^– ions.

Figure 2: Water Molecules Partially Dissociate into Ion

Since these weak electrolytes partially dissolve in water, a solution of weak electrolytes is composed of molecules, cations and anions. Since there are several electrically charged ions, these solutions can conduct an electric current.

Some common weak electrolytes are weak acids such as H₂CO₃, and weak bases such as NH₃. For weak electrolytes, the dissociation constants are important in predicting the capacity of electrical charge that can be conducted through a solution since the dissociation of the compound forms the soluble ions that can conduct electricity.

Difference Between Strong and Weak Electrolytes

Definition

Strong Electrolytes: Strong electrolytes are compounds that can completely dissociate into its ions when dissolved in water.

Weak Electrolytes: Weak electrolytes are compounds that partially dissociate into its ions when dissolved in water.

Dissociation

Strong Electrolytes: Strong electrolytes can completely dissociate into ions.

Weak Electrolytes: Weak electrolytes partially dissociate into ions.

Examples

Strong Electrolytes: Strong electrolytes are strong acids, strong bases, and some salts.

Weak Electrolytes: Weak electrolytes are weak acids, weak bases, and some salts.

Conclusion

Electrolytes are compounds that can dissolve in water to release cations and anions. These ions can contribute to the conduction of electricity through a solution. The main difference between strong electrolytes and weak electrolytes is that strong electrolytes can almost completely dissociate into its ions whereas weak electrolytes partially dissociate into ions.

References:

1. “Weak Electrolyte: Definition & Examples.” Study.com, Study.com, Available here. Accessed 15 Sept. 2017.
2. “Electrolytes — Strong, Weak, and Non Electrolytes.” Science Notes and Projects, 1 Apr. 2016, Available here. Accessed 15 Sept. 2017.

Image Courtesy:

1. “215 Acids and Bases-01” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia
2. “Autoprotolyse eau” By Cdang – Own work, Public Domain) via Commons Wikimedia