a clear colourless liquid used to test for a gas which your body gets rid of.
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The clear colorless liquid you are referring to is likely lime water, which is used to test for the presence of carbon dioxide (CO2) gas. Lime water is a solution of calcium hydroxide (Ca(OH)2) in water.
Here's an explanation of how lime water can be used to test for the gas your body gets rid of, which is carbon dioxide:
1. Preparation: Lime water can be prepared by dissolving calcium hydroxide powder (also known as lime or slaked lime) in water. The ratio of lime to water depends on the desired concentration of the solution.
2. Reacting with Carbon Dioxide: Lime water reacts with carbon dioxide gas to form a white precipitate called calcium carbonate (CaCO3). The chemical equation for this reaction is:
Ca(OH)2 + CO2 → CaCO3 + H2O
3. Test Procedure: To test for the presence of carbon dioxide, you would typically bubble the gas through a container of lime water. If carbon dioxide is present, it will react with the lime water, causing it to turn cloudy or form a milky white precipitate of calcium carbonate.
The reason lime water can be used to detect carbon dioxide is that when CO2 dissolves in water, it forms a weak acid called carbonic acid. This acid reacts with the calcium hydroxide in lime water to produce calcium carbonate, which is insoluble and causes the cloudiness or precipitation.
It's worth noting that lime water is not the only method to test for carbon dioxide, there are other chemical indicators and methods available as well.