Science Experiments for Testing Water Purity With a Boiling Point

Comparing Water Sources

• In this experiment you take five water samples from five different sources and test how hot they need to get before they are boiling. One of the samples is distilled, another is tap water, the remaining three are from a pond, a lake and a river. By heating the water over a Bunsen burner to boiling, you can find out how pure it is. Use a thermometer to measure the temperature of the water at boiling and mark it down for each of the water samples. The water with the highest boiling point is the least pure and the water with the lowest is the most pure.

Salt Water Test

• Start out with three different 100-milliliter beakers of distilled water. Add different amounts of salt to two of the beakers and mark down how much salt was added to each one. Insert a thermometer into each of the three beakers and heat them until they have reached their boiling point. Mark down the boiling point for each of the three beakers. Which of the three beakers boiled at the highest temperature? Did it have the highest amount of added salt or the lowest?

Impurities with a Higher Boiling Point than Water

• Over 99 percent of all impurities in most drinking water supplies have a higher boiling point than water itself. These impurities include minerals, heavy metals, nitrates, bacteria, dissolved solids, organic compounds and sodium. These are the most harmful contaminants, and most drinking water will be dramatically improved through distillation. There are some other contaminants known as Volatile Organic Contaminants, or VOCs, that have a boiling point very close to water. These contaminants cannot be removed using distillation, and other measures such as the addition of filters will have to be taken to remove them.

The Process of Distillation

• Distilled water is created in a device with at least two different sections. The water is heated to exactly 100 degrees Celsius, at which point it evaporates and rises into the air. When the water evaporates it leaves behind any of the impurities that have a higher boiling point. The water then travels into the other chamber of the distiller where the steam condenses it back into water again, only this time much purer. Although the distilled water is nearly free of impurities it has an unpleasant bland taste and it is normally more acidic than normal tap water. The removal of minerals lowers the pH of the water and takes away most of the pleasant flavor, leaving a bland-tasting liquid that isn̵7;t as pleasant to drink.