Yes, Calcium Hydroxide (Ca(OH)2) is considered a strong base. 1 When dissolved in water, it completely dissociates into calcium ions (Ca2+) and hydroxide ions (OH-), resulting in a high concentration of hydroxide ions in the solution, which makes it a strong base.
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Key Takeaways: Is Calcium Hydroxide a Strong Base?
- Calcium hydroxide (Ca(OH)2) is a strong base because it completely dissociates in water, releasing a high concentration of hydroxide ions (OH-) into the solution.
- In contrast, weak bases like ammonia (NH3) only partially dissociate in water, resulting in a lower concentration of hydroxide ions and a less significant impact on pH.
- Due to its strong basic nature, calcium hydroxide has various applications in water treatment, soil stabilization, construction, chemical processing, food industry, pH adjustment, and more.
Why is calcium hydroxide a strong base?
Calcium hydroxide (Ca(OH)2) is considered a strong base due to its ability to completely dissociate or ionize in water, releasing hydroxide ions (OH-) into the solution. This strong dissociation is a result of the unique properties of calcium hydroxide as a compound.
The strength of a base is determined by its ability to accept protons (H+) from water molecules. In the case of calcium hydroxide, it dissociates into calcium ions (Ca2+) and hydroxide ions (OH-) when mixed with water:
Ca(OH)2 (s) + H2O (l) → Ca2+ (aq) + 2 OH– (aq)
The hydroxide ions (OH-) produced in this reaction can readily accept protons from water, leading to an increase in hydroxide ion concentration and, therefore, an increase in pH. The higher the concentration of hydroxide ions in the solution, the stronger the base is considered. 2
In contrast, weak bases do not dissociate completely in water, and only a fraction of the compound forms hydroxide ions. As a result, their ability to accept protons and increase hydroxide ion concentration is limited, leading to a less significant impact on pH.
It’s important to note that the strength of a base does not solely depend on the metal ion (in this case, calcium) but also on the specific compound’s ability to dissociate in water. Other factors, such as ionic size and charge, can also influence the strength of the base.
How does the dissociation of calcium hydroxide differ from that of a weak base?
Here’s a comparison of the dissociation of calcium hydroxide (a strong base) and a weak base (for example, NH3).
| Aspect | Calcium Hydroxide (Strong Base) | Ammonia (NH3) (Weak Base) |
| Chemical Formula | Ca(OH)2 | NH3 |
| Dissociation Reaction | Ca(OH)2 (s) + H2O (l) → Ca2+ (aq) + 2 OH– (aq) | NH3 (aq) + H2O (l) → NH4+ (aq) + OH– (aq) |
| Degree of Dissociation | Complete dissociation 3 | Partial dissociation 4 5 |
| Concentration of OH- | High concentration of OH- ions in solution 6 7 8 | Lower concentration of OH- ions 9 |
| pH Effect | Significantly increases pH of the solution 10 | Slightly increases pH of the solution 11 |
| Strength as a Base | Strong | Weak |
In this comparison, we used ammonia (NH3) as the weak base example. When ammonia reacts with water, only a portion of it forms ammonium ions (NH4+) and hydroxide ions (OH-).
As a weak base, ammonia’s ability to accept protons from water is limited, resulting in a lower concentration of hydroxide ions and a less significant impact on pH compared to calcium hydroxide, which is a strong base that fully dissociates in water.
Applications of calcium hydroxide based on its strong basic nature
Calcium hydroxide, due to its strong basic nature, finds numerous applications across various industries and fields. Some of the notable applications include:
- Water Treatment: Calcium hydroxide is commonly used in water and wastewater treatment as a flocculant and pH regulator. 12 It helps remove impurities, neutralizes acidic water, and aids in the coagulation and settling of suspended particles.
- Soil Stabilization: In construction and agriculture, calcium hydroxide is used to stabilize and improve the quality of soils. It can reduce soil acidity, enhance clay properties, and increase load-bearing capacity. 13
- Construction: In construction, calcium hydroxide, also known as hydrated lime, is used to make lime mortar, lime plaster, and lime concrete. It improves workability and durability while enhancing the adhesion of materials.
- Chemical Processing: Calcium hydroxide is utilized in various chemical processes, such as in the production of calcium-based chemicals, alkalis, and calcium salts.
- Food Industry: It is used as a food additive (E526) for various purposes, including pickling, as a pH regulator, and in certain baking processes. 14
- pH Adjustment: Calcium hydroxide is employed in various industries to adjust pH levels in products and processes. It can be used to neutralize acidic solutions.
- Flue Gas Desulfurization (FGD): In power plants and industrial facilities, calcium hydroxide is utilized in FGD systems to remove sulfur dioxide (SO2) from flue gases, reducing harmful emissions. 15
- Leather Industry: In leather processing, calcium hydroxide is used for liming, a critical step in the initial stages of leather production. 16
- Drilling Fluids: In the oil and gas industry, calcium hydroxide is used in drilling fluids to control pH, prevent clay swelling, and improve wellbore stability.
- Paper Industry: It is used in the paper industry for water treatment, bleaching, and as a filler in paper products.
- Sugar Refining: Calcium hydroxide is used in the sugar industry to remove impurities during sugar refining.
- Disinfectant and Sanitizer: Calcium hydroxide’s basic nature gives it some antibacterial properties, making it useful in certain disinfection and sanitation applications. 17
It is important to handle calcium hydroxide with care, as it can cause skin and eye irritation, and proper safety precautions should be taken when using it in any application.
Further reading
Is LiOH a Strong Base?
Why is Perchloric Acid an Electrolyte?
Is Acetic Acid a Strong Electrolyte?
Is HNO3 a Strong Electrolyte?
Why is NaCl (Sodium Chloride) a Strong Electrolyte?
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References
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- Roesyanto, Iskandar, R., Puji Hastuty, I., & Arrasyid, R. (2020, May 1). A study of calcium hydroxide as a stabilizing agent in clay soil toward California bearing ratio and unconfined compression value. IOP Conference Series: Materials Science and Engineering, 801(1), 012023. https://doi.org/10.1088/1757-899x/801/1/012023
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- WO2021101381A1 – Process for dehairing and liming of hides, skins or pelts – Google Patents. (2019, November 22). WO2021101381A1 – Process for Dehairing and Liming of Hides, Skins or Pelts – Google Patents. https://patents.google.com/patent/WO2021101381A1/en
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