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Acids, Bases and pH
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  • 1. WHAT IS AN ION? An ion is a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule. When an atom is attracted to another atom because it has an unequal number of electrons and protons, the atom is called an ION. If the atom has more electrons than protons, it is a negative ion, or ANION. If it has more protons than electrons,it is a positive ion CATION. An atom can acquire a positive charge or a negative charge depending on the number of electrons in an atom is greater or less then the number of protons in the atom.
  • 2. ACID AND BASE CONCEPTS In Aqueous solutions, small percentage of the water molecules themselves break apart into ions. The ions formed are positively charged hydrogen ions (H+) and negatively charged hydroxide ion (OH-). For the chemical processes of life t owork correctly, the right balance of H+ ions and OH- ions is critical. Some chemical compounds contribute additonial H+ ions to an aqueous solution while others remove H+ ion from it. Hydroxide ion - Hydrogen ion +
  • 3. ACID AND BASE CONCEPTS Hydroxide ion - Hydrogen ion +
  • 4. ACID (ACIDS) A compound that donates H+ ions to a solutions is called an ACID (Hydrovhloric acid HCl in aqueous solution brakes completely in H+ and Cl-)
  • 5. BASE (BASES) A compound that removes H+ ions From an aqueous solution is called a BASE. Some bases (sodium hydroxide NaOH), do this by adding OH- ions, which then combine with H+ ions and form water molecules
  • 6. PH SCALE Describes how acidic or basic a solution is. Scale ranges from 0 (most acidic) to 14 (most basic or Alkaline) Lemon juice: ph 2 Grape juice : ph 3 ten times more H+ Neurtral : pure water or aqueous solutions that have an equal amounts of H+ and OH- ions. pH 7 are neither acidic nor basic. pH of the solution inside most living cells is close to 7
  • 7. BUFFERS Molecules in cells are very sensitive to concentrations of H+ and OH- The slight change in pH can be harmful to organisms. Many biological fluids contein BUFFERS: Substances that cause a solution to resist changes in pH. A buffer works by ACCEPTING H+ ions when their levels rise, and DONATING H+ ions when the levels fall, thereby maintaining a fairly constant pH in the solution.
  • 8. AN ENVIRONMENT FIT FOR LIFE • The abundance of the liquid water: water is needed for life • Planets location in the solar system:far enough so it recives a moderate quantity of energy but not so far away that temperatures are too cold • Ozone gas shields the planet´s surface from harmful radiation • Availability of essential elements for life: soil rocks and atmosphere.
  • 9. PH ACID BASE VIDEOS https://www.youtube.com/watch?v=RF40cI2O16U Cabache experiment