NH3 (Ammonia) is a weak base. 1 It does not completely dissociate into hydroxide ions (OH-) in water. Instead, it only partially ionizes, resulting in a lower concentration of hydroxide ions and a less alkaline pH compared to strong bases like KOH.
Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.
So let’s dive right into it.
Key Takeaways: Is NH3 a Strong or Weak Base?
- NH3 (Ammonia) is a weak base because it only partially dissociates into NH4+ and OH- ions in water, resulting in a lower concentration of hydroxide ions compared to strong bases.
- Strong bases, like NaOH, completely dissociate in water, leading to a higher concentration of OH- ions and a more alkaline pH.
- NH3 finds various applications in industries such as household cleaning products, fertilizers, refrigerants, water treatment, leavening agents, and more, due to its weak basic nature.
Why is NH3 a weak base?
NH3 is a weak base because it does not completely dissociate in water, resulting in a low concentration of hydroxide ions (OH-) in the solution. It only accepts a small number of protons from water molecules to form ammonium ions (NH4+), leading to a limited ability to neutralize acids.
NH3, ammonia, acts as a base by accepting a proton (H+) from water, forming NH4+ and OH-.
NH3 + H2O ⇌ NH4+ + OH-
However, this process is reversible, and NH4+ can also act as a weak acid, donating a proton back to OH- to regenerate NH3.
As a result, the concentration of OH- ions in the solution remains relatively low, limiting its capacity to neutralize acids. In contrast, strong bases like NaOH dissociate almost completely in water, providing a high concentration of OH- ions, 2 leading to more efficient acid neutralization.
The extent of dissociation and the concentration of OH- ions determine the strength of a base, and since NH3 only partially dissociates, it is classified as a weak base.
How does the dissociation of NH3 differ from that of a strong base?
Here is a table showing the comparison of the NH3 (Ammonia) with the strong base (e.g. NaOH).
| Aspect | NH3 (Ammonia) | Strong Base (e.g., NaOH) |
| Chemical Formula | NH3 | MOH (where M is an alkali metal) |
| Dissociation Reaction | NH3 + H2O → NH4+ + OH- | MOH → M+ + OH- |
| Degree of Dissociation | Weak dissociation in water. 3 4 | Complete dissociation in water. 5 |
| Dissociation Constant (Kb) | Relatively small Kb value. | Very large Kb value. |
| pH in Water | NH3 in water acts as a weak base, raising pH but staying close to neutral (pH ~ 9-12). | Strong base dissociates completely, leading to a high pH (pH ~ 13-14). |
| Conductivity | Poor conductor of electricity. 6 | Good conductor of electricity. 7 |
| Reaction with Acids | Acts as a base and reacts with acids to form ammonium salts (e.g., NH4Cl). | Neutralizes acids to form salts (e.g., NaCl). |
| Typical Uses | Ammonia is used in household cleaning products, refrigerants, and as a precursor for various chemicals. | Strong bases like NaOH are used in manufacturing, cleaning, and laboratory processes. |
The comparison above assumes typical laboratory conditions and a dilute aqueous solution for both NH3 and the strong base. Strong bases like NaOH dissociate almost completely in water, leading to the release of hydroxide ions (OH-) and a significant increase in pH.
On the other hand, NH3 is a weak base and only undergoes a partial dissociation in water, resulting in a relatively lower pH compared to strong bases.
Applications of NH3 based on its weak basic nature
Ammonia (NH3), due to its weak basic nature, finds various applications in different industries and processes. Some of the notable applications include:
- Household Cleaning Products: Ammonia is a common ingredient in household cleaning solutions, such as glass cleaners and floor cleaners, due to its ability to effectively dissolve grease and remove stains. 8
- Fertilizers: Ammonia is a crucial component in the production of nitrogen-based fertilizers like ammonium nitrate and urea. 9 10 These fertilizers provide essential nitrogen to the soil, promoting plant growth.
- Refrigerants: Ammonia is used as a refrigerant in industrial refrigeration systems due to its excellent cooling properties. 11 12 It is an environmentally friendly alternative to synthetic refrigerants that contribute to ozone depletion and global warming.
- Water Treatment: In water treatment, ammonia is used to adjust pH levels and control the formation of undesirable substances like chloramines, which can result from the reaction of chlorine with organic matter in water.
- Leavening Agent: Ammonia is used as a leavening agent in certain baked goods like cookies and biscuits. 13 When heated, it releases gas, creating a light and airy texture.
- Analytical Chemistry: In analytical chemistry, ammonia is used as a complexing agent and reagent in various tests and reactions.
- Textile Industry: Ammonia is used in the textile industry during the production of synthetic fibers like nylon and rayon. 14
- Rubber Industry: In the rubber industry, ammonia is used in the production of synthetic rubber.
- pH Buffering: Ammonia solutions can be used to create buffers with a specific pH range for various laboratory applications.
- Neutralizing Acid Spills: Due to its weak basic nature, ammonia can be used to neutralize small acid spills and accidents safely.
Further reading
Is NaOH (Sodium Hydroxide) a Strong or Weak Base?
Is Calcium Hydroxide [Ca(OH)2] a Strong Base?
Is LiOH a Strong Base?
Why is Perchloric Acid an Electrolyte?
Is Acetic Acid a Strong Electrolyte?
Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. He is a founder of Pediabay and is passionate about helping students through his easily digestible explanations.
Read more about our Editorial process.
References
- NH3, acid or base? – CHEMISTRY COMMUNITY. (n.d.). NH3, Acid or Base? – CHEMISTRY COMMUNITY. https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=39113
- Purdue.edu https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch11/acidbase.php
- Weak acid-base equilibria (article) | Khan Academy. (n.d.). Khan Academy. https://www.khanacademy.org/science/chemistry/acids-and-bases-topic/copy-of-acid-base-equilibria/a/weak-acid-base-equilibria
- Utexas.edu https://ch302.cm.utexas.edu/chemEQ/ab-theory/selector.php?name=weak-acid-base
- Ufl.edu https://christou.chem.ufl.edu/wp-content/uploads/sites/62/2017/01/Chapter-18-Acids-and-Bases-Week-1.pdf
- Acid and Base Strength. (2013, October 2). Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/Ionization_Constants/Acid_and_Base_Strength
- Elmhurst.edu http://chemistry.elmhurst.edu/vchembook/185strength.html
- P. (n.d.). Ammonia. Ammonia | NH3 | CID 222 – PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/222
- Yüzbaşıoğlu, A. E., Avşar, C., & Gezerman, A. O. (2022). The current situation in the use of ammonia as a sustainable energy source and its industrial potential. Current Research in Green and Sustainable Chemistry, 5, 100307. https://doi.org/10.1016/j.crgsc.2022.100307
- Iea.org https://www.iea.org/reports/ammonia-technology-roadmap/executive-summary
- Epa.gov https://www.epa.gov/sites/default/files/documents/ASHRAE_PD_Ammonia_Refrigerant_2010_1.pdf
- Pearson, A. (2008, June). Refrigeration with ammonia. International Journal of Refrigeration, 31(4), 545–551. https://doi.org/10.1016/j.ijrefrig.2007.11.011
- Huang, S., & Miskelly, D. (2016). Optional Ingredients for Dough. Steamed Breads, 47–63. https://doi.org/10.1016/b978-0-08-100715-0.00004-5
- Ammonia | Definition & Uses. (n.d.). Encyclopedia Britannica. https://www.britannica.com/science/ammonia