Observe the figure and answer the following questions: (a) Which gas is released as effervescence in the big test tube? (b) What is the colour change in the lime water? (c) Write the related chemical equation.
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Remember: Carbon dioxide gas is produced when an acid reacts with a carbonate.
In the figure, sodium carbonate reacts with acetic acid to produce carbon dioxide gas. This gas is released as effervescence in the big test tube. The gas released is carbon dioxide (CO2). This gas is produced due to the reaction between acetic acid and sodium carbonate.
(a)) The gas released is carbon dioxide (CO2). The effervescence observed is due to the formation of carbon dioxide gas as sodium carbonate reacts with acetic acid.
(b) When carbon dioxide gas (CO2) passes through freshly prepared lime water (calcium hydroxide solution), it forms calcium carbonate, which is insoluble and precipitates out, turning the lime water milky. The reaction is as follows: Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O (l) The lime water turns milky due to the formation of calcium carbonate.
(c) The chemical equation for the reaction between sodium carbonate and acetic acid is: Na₂CO₃ (aq) + 2CH₃COOH (aq) → 2CH₃COONa (aq) + CO₂ (g) + H₂O (l) This equation shows the production of carbon dioxide gas (CO2), which is released as effervescence.
