In the experimental set-up shown above in diagram (I) atmospheric air is being passed into lime water with a syringe while in diagram (II) air is being exhaled into lime water. The time taken for the lime water to turn milky in both the test tubes is different. Give reason.
Experiment Description: Two air types, atmospheric and exhaled, are bubbled through separate lime water (Ca(OH)₂) solutions. Diagram (I) represents atmospheric air, and Diagram (II) represents exhaled air.
Air Sample Composition: Atmospheric air contains approximately 0.03–0.04% CO₂. Exhaled air has a significantly higher CO₂ concentration, around 4%.
Reaction Mechanism: Carbon dioxide from the air reacts with calcium hydroxide in lime water. This reaction produces insoluble calcium carbonate, causing the lime water to turn milky: \[\text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \text{H}_2\text{O}\] The formation of calcium carbonate (CaCO₃) is responsible for the observed milkiness.
Experimental Observations: Test tube (I) shows slow milkiness development due to the low CO₂ content in atmospheric air. Test tube (II) exhibits rapid milkiness formation because exhaled air, rich in CO₂, reacts more quickly with lime water.
Experimental Conclusion: The accelerated milkiness in test tube (II) demonstrates that exhaled air contains a greater amount of carbon dioxide compared to atmospheric air, leading to a faster reaction rate with lime water.
