Final answer:
The chlorine to water ratio to obtain a sanitizer level is dependent on the desired ppm level; for pool water, a maximum of 3.0 ppm is standard. Chlorine plays a critical role in oxidizing organic substances in water purification. Measurement methods include determining chlorine demand and residual, with sodium hypochlorite often used as the active ingredient in bleach.
Step-by-step explanation:
To achieve proper sanitization, it is important to maintain the correct chlorine concentration in water. For instance, to maintain a safe water quality, pools are often chlorinated to a level of 3.0 parts per million (ppm). In the scenario of a typical 5,000 gallon pool with 21,200 kg of water, one would need to determine the mass of chlorine needed to attain this concentration.
It's also noted that chlorine's use goes beyond just pool water. It plays a significant role in water purification and bleaching by oxidizing and eliminating organic or biological materials. The chemical reaction of this process can be summarized by the equation P4 (s) + 10Cl2 (g) → 4PCl5 (l). This illustrates the formation of phosphorus pentachloride from phosphorus and chlorine gas, hinting as to how reactive chlorine is with other substances.
To measure chlorine levels in a water supply, various methods like chlorine demand and determination of chlorine residual are used. This involves analyzing how much chlorine is used up by the water supply and what concentration remains. The chlorine residual can exist in different forms, and is measured by titrating it with sodium thiosulfate and using starch as an indicator. Liquid bleach, commonly used for water sanitization, typically contains a sodium hypochlorite (NaOCl) concentration, which is often expressed as a mass percentage such as 7.4%.