Analysis of Bottled Water

I. pH – Form A

The pH value of water helps determine whether water is hard or soft.  Water with a pH > 8.5 may indicate hardness and alkalinity.  Water with a pH < 6.5 indicates that the water is soft, acidic and possibly corrosive.  In this case, the water may contain toxic metals such as iron, copper, lead, or zinc.  Typically, the pH of drinking water ranges from 5.5 to 9.0.

Sources:

http://www.freedrinkingwater.com/water-education/quality-water-ph.htm

http://www.idph.state.il.us/envhealth/pdf/DrinkingWater.pdf

http://www.epa.gov/acidrain/site_students/images/phscale.gif

pH = -log [H⁺]

Procedure:

• Calibrate pH meter using the instructions supplied with your specific pH meter
• Rinse probe with DI water before submerging in water sample
• Submerge probe in water sample and record the pH
• Rinse probe with DI water
• Record your pH data below
• Transfer all your data to the class data sheet - Form F
• **Always keep the pH electrode submerged in a buffer solution when not in use**

pH Data

Type and Brand of Water

pH

pH Levels of Drinking Water

Less than 5.5	Acidic
5.5-9.0	Normal
Higher than 9.0	Alkaline

Questions:

1. What was the pH range among the various water samples?
2. In order for water to be consumed by humans, its pH should be close to neutral (7.0).  How close is the pH of each bottled water sample to 7.0?
3. As mentioned earlier, water with a pH > 8.5 may indicate hardness where as water with a pH < 6.5 may be soft.  Compare the pH and hardness levels of each water sample in order to determine this relationship.