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Bases

Acids. and. Bases. http://www.chalkbored.com/lessons/chemistry-11/acid-bronsted.ppt. Water. Water is an inorganic Molecule TO BE ORGANIC, A MOLECULE MUST HAVE CARBON IN IT What is the Chemical Formula for Water? So, it can’t be organic!. What is weird about water?. Remember Polarity?

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Bases

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  1. Acids and Bases http://www.chalkbored.com/lessons/chemistry-11/acid-bronsted.ppt

  2. Water • Water is an inorganic Molecule • TO BE ORGANIC, A MOLECULE MUST HAVE CARBON IN IT • What is the Chemical Formula for Water? • So, it can’t be organic!

  3. What is weird about water? • Remember Polarity? • We did the “pom-pom” lab an learned that some molecules are not linear • Water has opposite charges at opposite ends • This gives water several unique properties

  4. Water molecules display PolarityAnd this Polarity causes: Cohesion & Adhesion & Surface Tension (Remember? We learned about the meniscus in a test tube)

  5. Cohesion – Water molecules stick to each other Adhesion – Water molecules stick to other molecules Surface Tension – The “tension” (almost like a film) on the surface of water caused by cohesion Meniscus – The “curve” at the top surface of water in a graduated cylinder caused by adhesion

  6. Dissociates • Water is made up of two different elements • 2 atoms of Hydrogen • 1 atom of Oxygen • When water dissociates (breaks apart) it forms two different ions • Hydroxide (-OH) • Hydrogen (+H) • An ion is a molecule that has a charge • Can be positive or negative

  7. Swimming Pools • Ever open your eyes in a swimming pool and they end up red and burning?

  8. Heartburn? • Have you ever had heartburn? • Sometimes called Gerd • It feels like your heart is on fire • It is caused by stomach acid “climbing up” your esophagus

  9. How do you get rid of it? • Since heartburn is caused by stomach acid climbing up the esophagus… • You neutralize it with “antacids” • Which are basic!

  10. Acids & Bases are Based on WATER! • Depending on the amount of H+ or OH- ions, the “water” becomes either acidic or basic (aka alkaline) • The pH scale determines the strength of the acid/base • The pH scale runs from 0 -14 • Low numbers are acidic • High numbers are alkaline • “7” is neutral  Water A comes before B

  11. The pH Scale

  12. pH scale measures acidity/basicity Søren Sorensen (1868 - 1939) ACID BASE 10x 100x 10x 10x 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 NEUTRAL Each step on pH scale represents a factor of 10 pH 5 vs. pH 6 (pH 5 is 10X more acidic) pH 3 vs. pH 5 (2 steps = 10x10 = 100X difference) pH 8 vs. pH 13 (5 steps = 10x10x10x10x10 = 100,000X difference)

  13. Characteristics of Acids • Taste Sour • Conduct Electricity • Corrosive, which means they break down certain substances. Many acids can corrode fabric, skin and wood • Some acids react strongly with metals • Turns blue litmus paper red • Turn pH Paper Yellow  Red • Depending on strength of acid

  14. Characteristics of Basesaka - Alkalis • Feel Slippery (Think SOAP!) • Taste Bitter • Corrosive (Just as corrosive as Acids!) • Can conduct electricity. (Think alkaline batteries.) • Do not react with metals • Turns red litmus paper blue • Turn pH paper Green  Blue • Turn Phenolphthalein  Pink

  15. Acids/Bases • The lower the pH, the stronger the acid • The higher the pH, the stronger the base • Did you know the human body produces BUFFERS to maintain homeostasis • Buffers help to neutralize acids and bases

  16. Acid – Base Reactions • A reaction between an acid and a base is called neutralization. • An acid-base mixture is not as acidic or basic as the individual starting solutions.

  17. Acid – Base reactions • Acid + Base = Salt + Water! • Each salt listed in this table can be formed by the reaction between an acid and a base. • Neutralization

  18. Neutralization • To neutralize (counter-act) an acid, you add a base • To neutralize (counter-act) a base, you add an acid • The Buffers your body produces are either acidic or basic...

  19. Buffers • A buffer is a solution the helps return another solution to its proper pH • A buffer can “soak up” excess H+ ions (acid) or “soak up” excess OH- ions (base) • Your body produces buffers ALL THE TIME in order to maintain homeostasis • Think about all of the acidic stuff you eat!

  20. [H+] M A strong acid 100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 A strong base 10-13 10-14 SOURCE: http://en.wikipedia.org/wiki/Image:PH_scale.png#file pH • Most living organisms have a very narrow range of tolerance for pH • Remember…Each pH unit represents a factor of 10 difference in [H+] • How do we figure out what’s an acid and what’s a base? LITMUS or pH PAPER! 20 The pH scale goes from 0 to 14—because [H+][OH-] = 10-14

  21. pH Paper • An indicator for pH • Turns different colors in different solutions • Acid  Red • Base (Alkali)  Blue • Neutral  Lt. Green

  22. Let’s Try It Out! • We will be using Litmus paper to determine the pH of several household items!

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