The key difference between calcium hypochlorite and sodium hypochlorite is that the calcium hypochlorite contains two hypochlorite anions associated with one calcium cation whereas sodium hypochlorite contains one hypochlorite anion associated with one sodium cation. In appearance, calcium hypochlorite is a white to a grey powder while sodium hypochlorite is a greenish-yellow solid with a sweet odour.
Calcium and sodium hypochlorite are ionic compounds containing a metal cation and a chlorine-derived anion. The number of anions per cation of these compounds differs from each other according to the valency of the metal cation.
CONTENTS
1. Overview and Key Difference
2. What is Calcium Hypochlorite
3. What is Sodium Hypochlorite
4. Side by Side Comparison – Calcium Hypochlorite vs Sodium Hypochlorite in Tabular Form
5. Summary
What is Calcium Hypochlorite?
Calcium hypochlorite is an inorganic compound with the chemical formula Ca(OCl)2. The molar mass is 142.98 g/mol. It appears as a white to a grey powder. The melting and boiling points are 100 °C and 175 °C respectively. At higher temperatures, it decomposes. This compound is relatively stable. It has a greater amount of available chlorine than that of sodium hypochlorite. It has a strong smell of chlorine. This is due to its slow decomposition in moist air. However, it is not that much soluble in hard water. But we can dissolve it in soft to medium hard water. Moreover, there are two forms of this as, anhydrous form and hydrated form.
Figure 01: Chemical Structure of Calcium Hypochlorite
The applications of this compound are mainly in sanitation and organic chemistry. We can use it to sanitize water in swimming pools and to disinfect drinking water. Generally, the purity of commercial grade calcium hypochlorite is around 65-73% because it has other compounds mixed with it. In organic chemistry, it acts as an oxidizing agent.
What is Sodium Hypochlorite?
Sodium hypochlorite is an inorganic compound with the chemical formula NaOCl. The molar mass is 74.45 g/mol. It appears as a greenish-yellow solid. It has a sweet odour. The melting point and boiling points of the most common hydrate of this compound (pentahydrate form) are 18 °C and 101 °C respectively. This compound is highly unstable and thus, decomposes explosively upon heating or even friction. However, the pentahydrate form is more stable than the anhydrous form.
Figure 02: Chemical Structure of Sodium Hypochlorite
The applications of sodium hypochlorite are in bleaching, cleaning, disinfection, deodorizing, wastewater treatment, etc. This compound is commonly known as liquid bleach, which has a pale yellow to green colour. Moreover, it is a common household chemical.
What is the Difference Between Calcium Hypochlorite and Sodium Hypochlorite?
There are many differences between calcium hypochlorite and sodium hypochlorite in their chemical and physical properties. Calcium hypochlorite is an inorganic compound with the chemical formula Ca(OCl)2. Sodium hypochlorite is an inorganic compound with the chemical formula NaOCl. The melting and boiling points of calcium hypochlorite are very high compared to that of sodium hypochlorite. When considering the chemical structure of these two compounds, calcium hypochlorite contains two hypochlorite anions associated with one calcium cation whereas sodium hypochlorite contains one hypochlorite anion associated with one sodium cation. Moreover, calcium hypochlorite is more stable than sodium hypochlorite.
The below infographic presents more details on the difference between calcium hypochlorite and sodium hypochlorite in tabular form.
Summary – Calcium Hypochlorite vs Sodium Hypochlorite
Both calcium and sodium hypochlorite compounds are important as bleaching agents and disinfectants. The key difference between calcium hypochlorite and sodium hypochlorite is that calcium hypochlorite contains two hypochlorite anions associated with one calcium cation whereas sodium hypochlorite contains one hypochlorite anion associated with one sodium cation.
Reference:
1. “Calcium Hypochlorite.” Wikipedia, Wikimedia Foundation, 22 Aug. 2018. Available here
2. “Sodium Hypochlorite.” Wikipedia, Wikimedia Foundation, 18 Aug. 2018. Available here
Image Courtesy:
1.”Calcium hypochlorite” By Epop – Own work, (Public Domain) via Commons Wikimedia
2.”Sodium-hypochlorite” By Benjah-bmm27 – Own work, (Public Domain) via Commons Wikimedia