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REVIEW QUIZ

REVIEW QUIZ. What does UBIQUITOUS mean? How does High Specific Heat relate to your swimming pool? What is surface tension? Draw the water molecule , add the charges. What is adhesion, cohesion and how do they relate to capillary action? What does UNIVERSAL SOLVENT mean?. pH Notes.

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REVIEW QUIZ

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  1. REVIEW QUIZ • What does UBIQUITOUS mean? • How does High Specific Heat relate to your swimming pool? • What is surface tension? • Draw the water molecule , add the charges. • What is adhesion, cohesion and how do they relate to capillary action? • What does UNIVERSAL SOLVENT mean?

  2. pH Notes Directions: Take notes Do Lab Review

  3. pH PRE Quiz • What does pH stand for? • What is neutral on the scale? • What liquid represents neutral? • What is the highest rating on the scale? • Is the highest rating an acid or base? • What is the lowest rating? • Is the lowest rating an acid or base?

  4. pH Defined • pH is defined as the negative logarithm of the hydrogen ion concentration: pH = - log [H+] • pH stands for “potential for Hydrogen”

  5. What is pH? • The pH scale measures how acidic or basic a substance is. • The pH scale ranges from 0 to 14. • A pH less than 7 is acidic. • A pH of 7 is neutral. • A pH greater than 7 is basic. http://www.elmhurst.edu/~chm/vchembook/184ph.html

  6. ? Logarithms ? • Logarithms of numbers that are multiples of ten are merely the exponents of the number including the sign.

  7. Soo… • The pH scale is logarithmic and as a result, each whole pH value ten times more or less concentrated. • For example, pH 4 is ten times more acidic than pH 5 and 100 times (10 times 10) more acidic than pH 6. • For example, pH 10 is ten times more alkaline than pH 9 and 100 times (10 times 10) more alkaline than pH 8.

  8. How it works • In pure water (H2O), there are an equal number of hydrogen ions (H) and hydroxyl ions (OH). The solution is neither acidic or basic.

  9. Dissociation • It all has to do with hydrogen ions (H+). In water (H2O), a small number of the molecules dissociate (split up).

  10. Some of the water molecules lose a hydrogen and become hydroxyl ions (OH−) or bases. • The "lost" hydrogen ions join up with water molecules to form hydronium ions (H3O+) or acids.

  11. So as the H+ conc. ↑ the OH- ↓ and visa versa

  12. RCC • Draw and label a HYDRONIUM molecule. • Draw and label HYDROXIDE molecule. • Why is water neutral? • What does dissociate mean? • If you add acid to a pH 3 does the pH increase or decrease? • If you add acid to a pH 10 does the pH increase or decrease? • If you remove base from a pH 9 does the pH increase or decrease? • If you remove acid from a pH 6 does the pH increase or decrease?

  13. Household items • pH is measured with a pH meter or with Litmus paper – which you used in your lab.

  14. Properties of Acids (H+) • Sour taste (do not taste!) • Change indicator to red • React with active metals to form hydrogen gas and a metal compound • contains hydrogen • Proton donors

  15. Properties of Bases (OH-) • bitter taste (Do not taste!) • slippery to the touch (DO not Touch!) • change indicator to blue • Emulsify (combine) fats and oils (thereby making them useful cleaning agents) • contain the OH- ion • proton acceptors.

  16. When acids and bases mix… • A salt is any compound which can be derived from the neutralization of an acid and a base. • The word "neutralization" is used because the acid and base properties of H+ and OH- are destroyed or neutralized. • In the reaction, H+ and OH- combine to form HOH or H2O or water molecules. • See demo • (A salt and water are produced)

  17. Danger! • Acids and bases are examples of corrosive poisons which react locally on tissue cells. • Chemicals that are very basic or very acidic are reactive. • These chemicals can cause severe burns, causing ultimate disintegration of the tissue. • The eyes and lungs are particularly sensitive to corrosive poisons.

  18. Life • Biological systems operate within a narrow pH range and can be negatively impacted by a change of pH. - Blood 7.35-7.45 - Salt water fish 8.0 and higher - Fresh water fish 5.5 – 7.5 - Swimming pool 7.0-7.6

  19. Conclusion…pH is good to know • pH AND YOU – REVIEW • CRASH COURSE • Get HW sheet • DO HW sheet • Tomorrow we will CHECK HW sheet • Monday we will have an assessment

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