pH: The Concentration of Positive Hydrogen Ions - PowerPoint PPT Presentation

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pH: The Concentration of Positive Hydrogen Ions

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  1. pH:The Concentration of Positive Hydrogen Ions By Arian Sayed & Mike Greco

  2. Definition: -pH is the concentration of positive hydrogen ions in gram atoms per liter. It is measured on a scale of 0-14, with low numbers (0-6) being acids and high numbers (8-14) bases. 7 is neutral, pure water. The concentration of hydrogen ions are expressed in scientific notation with negative powers of 10 (from to the zeroth – to the negative fourteenth). Example: Water= 1x10^-7 (Neutral) NaOH= 1x10^-14 (Most basic) HCl=1x10^0 (Most acidic)

  3. Ranges of pH in Nature: - An acceptable range of pH specifically in river water is 6-8 on the pH scale.

  4. Possible Sources of pH: Everything that has a molecular structure containing hydrogen atoms has a definite pH level. Pollution can occur quite easily this way. The dumping of substances into a fresh water source can drastically affect the pH of the water itself and disrupt the living ecosystem within. Example: -plastic bottles - nuclear waste -acid rain

  5. Excess or Lack of pH Can Cause: Illness in organisms Imbalance of a food chain Drastic changes in habitat of water life Infertility of soil Weathering of river banks and certain rocks

  6. Ways to Alleviate pH in Water Systems: • There are limited ways to make any change to the imbalance of pH: • Taking steps to lower the rate of pollution •  Perform routine water checks to reduce the environment of organic buildup • Most causes of pH changes are natural, and therefore are next to impossible to change

  7. pH Scale in Terms of Positive Hydrogen Ions: • It all has to do with hydrogen ions (abbreviated with the chemical symbol H+). In water (H2O), a small number of the molecules dissociate (split up). Some of the water molecules lose a hydrogen and become hydroxyl ions (OH−). The "lost" hydrogen ions join up with water molecules to form hydronium ions (H3O+). For simplicity, hydronium ions are referred to as hydrogen ions H+. In pure water, there are an equal number of hydrogen ions and hydroxyl ions. The solution is neither acidic or basic. • Scientists use a logarithmic scale in order to deal with these massive and tiny numbers. Each one-unit change in the pH scale corresponds to a ten-fold change in hydrogen ion concentration. The pH scale ranges from 0 to 14. It's a lot easier to use a logarithmic scale instead of always having to write down all those zeros! Notice how one hundred million million is a one with fourteen zeros after it.

  8. Bibliography: http://images.tutorvista.com/content/feed/tvcs/phscale.jpg http://www.visionlearning.com/library/module_viewer.php?mid=58 http://dictionary.reference.com/browse/Ph http://www.sciencebuddies.org/science-fairprojects/project_ideas/Chem_AcidsBasespHScale.shtml