Carbon dioxide (exp:5) - assignment - Q-A

Determination of Carbon-di-oxide in Water
(1) Q: Discuss the environmental significance of “carbon dioxide” water.
Ans: Corrosion is the principal difficulty caused by carbon dioxide. This gas on solution in water producing carbonic acid resulting in lowering of pH value and thus produces corrosive characteristic in water. Severe corrosion of heat exchanger, pipes, valves etc. can result where appreciable quantities of free carbon dioxide are present in water. Corrosion from carbon dioxide is boiler system is most frequently encountered in steam and return lines. Even though the boiler feed water contains no free carbon dioxide, appreciable concentration of this corrosive gas may come from carbonate and bicarbonate of the boiler feed water.
Although Bangladesh Environment Conservation Rule (1997) does not set any limit for its presence in drinking water, limits for carbon dioxide has been prescribed for many industrial uses.
(2) Q: Why groundwater usually contains more carbon dioxide compared to surface water?
Ans: Water is a universal solvent. Carbon dioxide is highly soluble in water. Carbon dioxide enters water in appreciable quantities as the water percolates through soil in which plants are growing. Dissolved in water, it forms carbonic acid which, together with the carbonates and bicarbonates. Surface water is exposed to the atmosphere. In surface water carbon dioxide easily escapes to the atmosphere. So groundwater usually contains more carbon dioxide compared to surface water
(3) Q: Why the test for carbon dioxide should be performed immediately after collection of water sample? Explain.
Ans: The test for carbon dioxide should be performed immediately after collection of water sample because, if there is present carbon dioxide in sample water, easily escaped to the atmosphere.

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