NH3 (Ammonia) is a weak electrolyte. It only partially dissociates into ammonium ions (NH4+) and hydroxide ions (OH-) when dissolved in water, resulting in limited electrical conductivity compared to strong electrolytes.
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Key Takeaways: Is NH3 a Strong Electrolyte?
- Ammonia (NH3) is a weak electrolyte because it only partially dissociates into ions (NH4+ and OH-) when dissolved in water.
- Strong electrolytes fully dissociate into ions, leading to a higher concentration of ions in the solution, while weak electrolytes have a lower degree of dissociation and a lower ion concentration.
- The dissociation of NH3 can be represented by the equilibrium reaction: NH3 (aq) + H2O (l) ⇌ NH4+ (aq) + OH- (aq).
Why is NH3 a weak electrolyte?
Ammonia (NH3) is considered a weak electrolyte because it only partially dissociates into ions when dissolved in water.
In the context of electrolytes, substances can be classified into three categories based on their ability to conduct electricity when dissolved in a solvent (usually water): 1
#1) Strong electrolytes: These substances completely dissociate into ions when dissolved in water, leading to a high concentration of ions in the solution. Examples include ionic compounds like NaCl (sodium chloride) or strong acids like HCl (hydrochloric acid). 2
#2) Weak electrolytes: These substances only partially dissociate into ions when dissolved in water, resulting in a lower concentration of ions in the solution. 3 4 Ammonia falls into this category because it can donate a few of its protons (H+) to form ammonium ions (NH4+) and hydroxide ions (OH-) in the presence of water, but not all of it dissociates.
The dissociation of ammonia in water can be represented by the following equilibrium reaction: 5
NH3 (aq) + H2O (l) ⇌ NH4+ (aq) + OH- (aq)
#3) Non-electrolytes: These substances do not dissociate into ions when dissolved in water, and thus they do not conduct electricity. 6 Examples include most organic compounds, such as sugars and alcohols.
So, while ammonia can conduct electricity to some extent due to the presence of ions in solution, it is considered a weak electrolyte because the majority of ammonia molecules remain undissociated as NH3 molecules. Strong acids and ionic compounds, on the other hand, form a much larger number of ions, making them better conductors of electricity and classified as strong electrolytes.
Degree of dissociation of NH3 compared to a strong electrolyte
The degree of dissociation of NH3 is lower compared to that of a strong electrolyte. While NH3 partially dissociates into NH4+ and OH- ions in water, a strong electrolyte like HCl or NaCl fully dissociates into their constituent ions, resulting in a higher concentration of ions in the solution.
When NH3 dissolves in water, it undergoes partial dissociation according to the equation:
NH3 (aq) + H2O (l) ⇌ NH4+ (aq) + OH- (aq)
This means only a fraction of NH3 molecules dissociate into ions, while most remain as NH3 molecules.
In contrast, strong electrolytes like HCl or NaCl fully dissociate into their constituent ions when dissolved in water.
HCl (aq) fully dissociates into H+ (aq) and Cl- (aq) ions, and NaCl (aq) fully dissociates into Na+ (aq) and Cl- (aq) ions. Consequently, the concentration of ions in the solution is much higher for strong electrolytes than for NH3 due to its partial dissociation.
As a result, NH3 is considered a weak electrolyte with a lower degree of dissociation compared to strong electrolytes.
Further reading
Is HF a Strong Electrolyte?
Is Ethanol (C2H5OH) an Electrolyte?
Is Volume a Physical or Chemical Property?
Is Malleability a Physical or Chemical Property?
Is Hardness a Physical or Chemical Property?
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References
- Umb.edu http://ocw.umb.edu/chemistry/chem-115-chemical-principles-i/Electrolytes.pdf/at_download/file.pdf
- Stolaf.edu https://www.stolaf.edu/depts/chemistry/courses/toolkits/121/js/naming/elec.htm
- Study.com https://study.com/learn/lesson/what-is-a-weak-electrolyte.html
- 7.7: Solution Equations: Weak Electrolytes. (2020, June 22). Chemistry LibreTexts. https://chem.libretexts.org/Courses/Heartland_Community_College/CHEM_120%3A_Fundamentals_of_Chemistry/07%3A_Solutions/7.07%3A_Weak_Electrolytes
- Equation for NH3 + H2O (Ammonia + Water). (2021, September 5). YouTube. https://www.youtube.com/watch?v=EJbXybLQDWk
- 7.5: Solution Equations: Non-Electrolytes. (2020, June 22). Chemistry LibreTexts. https://chem.libretexts.org/Courses/Heartland_Community_College/CHEM_120%3A_Fundamentals_of_Chemistry/07%3A_Solutions/7.05%3A_Non_Electrolytes
