Fahad Khalid Alhammadi 11-05 PH and water
Index: • Introduction to (pH). (slide 3) • pH of water.(slide 4) • The composition of water.(slide 5) • The concentration of hydrogen ions (pH) can affect the organisms that live in water.(slide 6) • Thing that can change the concentration of hydrogen ions (pH) in water.(slide 7) • The difference between an acidic, basic and natural (pH).(slide 8) • Comparison of bottled water. (slide 9)
What is pH? pH stands for the "power of Hydrogen" and measures the concentration of hydrogen ions in a solution, such as water. What is a hydrogen "ion?" It is an atom of hydrogen that has lost its electron. In water, hydrogen automatically gives up its electron to form ions.
pH of water: The technical definition of pH is that it is a measure of the activity of the hydrogen ion (H+) and is reported as the reciprocal of the logarithm of the hydrogen ion activity. Therefore, a water with a pH of 7 has 10-7 moles per liter of hydrogen ions; whereas, a pH of 6 is 10-6 moles per liter. The pH scale ranges from 0 to 14.
What is the composition of water? Everyone is very familiar with water. We observe it as rain and snow and can see it in the oceans, lakes, rivers, and streams. Although the water in our bodies is not as apparent, recognize that most of our weight is made up of water. In fact, the normal adult is made up of approximately 60% water. Thus, water is essential for life. Water is made up of hydrogen ions (H+) linked to hydroxyl ions (OH-) to form H2O. The molecular formula for water is H2O. From this formula and the atomic weights for hydrogen and oxygen you can calculate that the molecular weight of water is approximately 18 grams.Note: The atomic weight of hydrogen (H) is 1 gram and the atomic weight of oxygen (O) is 16 grams.
The concentration of hydrogen ions (pH) can affect the organisms that live in water. Aquatic organisms have adapted over time to survive and reproduce in a relatively narrow range of hydrogen ion concentrations. Some bacteria can withstand environments that have high hydrogen ion concentrations (pH = 2 or 3); other bacteria can live at very low hydrogen ion concentrations (pH = 12 or 13). However, most fish can only survive and reproduce in a water that is not very acidic or basic, but is water that is "just right". Most fish survive best in water that is close to "neutral" or, in terms of pH, at a pH between 6.5 and 8.2. Immature stages of aquatic insects (mayfly nymphs, stonefly nymphs, caddis fly larvae), snails, tadpoles, and crayfish are also very sensitive to changes in hydrogen ion concentration and seem to reproduce and survive best under "neutral" conditions (pH = 6 to 8). In water that is very acidic (low pH values), the concentration of heavy metals ions (copper, aluminum, etc.) increases and, this in turn, has negative effects on the health of aquatic organisms.
Things that can change the concentration of hydrogen ions (pH) in water. Rain water normally has a pH of approximately 5.6. However, airborne pollutants generated from industrial plants and automobiles burning fossil fuels create nitrous oxides and sulfur dioxides. These airborne ions can combine with water vapor to form nitric acid and sulfuric acid. In the presence of such pollution, rain water will become more acidic; as low as pH = 4.0. This acid rain, therefore, has more than 10 fold greater concentrations of hydrogen ions than normal rain water. When this acid rain runs into lakes, river, or streams, the pH of these bodies of water can be changed to levels that are not compatible with aquatic life.
The difference between an acidic, basic and neutral pH. • Any solution having a pH less than 7.0 is said to be acidic. • Any solution having a pH greater than 7.0 is said to be basic. • Neutral solutions have pH values of 7.0 (or very close to 7.0).