Lime water can be used to detect carbon dioxide but it cannot be used to absorb carbon dioxide. Why?
To understand why lime water can be used to detect carbon dioxide but not absorb it, we need to explore the properties of lime water and the reaction involved.
Lime water is a saturated solution of calcium hydroxide (Ca(OH)2) in water. When carbon dioxide (CO2) is passed through lime water, a chemical reaction occurs, resulting in the formation of a white precipitate called calcium carbonate (CaCO3).
The reaction can be represented as follows:
Ca(OH)2 + CO2 → CaCO3 + H2O
The white precipitate of calcium carbonate is insoluble in water, making it visible as a cloudy or milky appearance in the lime water. This reaction serves as an indicator for the presence of carbon dioxide. Lime water can, therefore, be used as a simple and inexpensive method to detect the presence of carbon dioxide gas.
However, lime water cannot efficiently absorb or remove large amounts of carbon dioxide from the atmosphere. This is because the reaction between lime water and carbon dioxide is relatively slow, and the calcium carbonate precipitate that forms in the reaction layer can block further reaction between the lime water and carbon dioxide. Consequently, lime water is not considered a practical or effective method for carbon dioxide absorption.
To efficiently absorb carbon dioxide, other methods such as using soda lime or specialized chemical absorbents that can rapidly react with and capture carbon dioxide are more suitable. These methods are commonly used in applications such as carbon dioxide scrubbers in industrial processes or rebreather systems in scuba diving.
In summary, lime water can be used to detect carbon dioxide due to the visible formation of calcium carbonate precipitate. However, it is not effective for absorbing carbon dioxide due to the slow reaction rate and the blocking of further reaction by the precipitate formed.