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Acids & Bases

Acids & Bases. They are everywhere.. In your food In your house EVEN IN YOU!!!!!. What is an acid?. An acid is a solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour". The more H + ions, the more acidic the solution. Properties of an Acid.

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Acids & Bases

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  1. Acids & Bases They are everywhere.. In your food In your house EVEN IN YOU!!!!!

  2. What is an acid? • An acid is a solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour". • The more H + ions, the more acidic the solution.

  3. Properties of an Acid • Tastes Sour • Conduct Electricity • Corrosive, which means they break down certain substances. Many acids can corrode fabric, skin,and paper • Some acids react strongly with metals • Turns blue litmus paper red

  4. Uses of Acids • Acetic Acid = Vinegar • Citric Acid = lemons, limes, & oranges. It is in many sour candies such as lemonhead & sour patch. • Ascorbic acid = Vitamin C which your body needs to function. • Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics. • Car batteries

  5. What is a base? • A base is a solution that has an excess of OH- ions. • Another word for base is alkali. • Bases are substances that can accept hydrogen ions

  6. Properties of a Base • Feel Slippery • Taste Bitter • Corrosive • Can conduct electricity. (Think alkaline batteries.) • Do not react with metals. • Turns red litmus paper blue.

  7. Uses of Bases • Bases give soaps, ammonia, and many other cleaning products some of their useful properties. • The OH- ions interact strongly with certain substances, such as dirt and grease. • Chalk and oven cleaner are examples of familiar products that contain bases. • Your blood is a basic solution.

  8. Let’s examine the behavior of an acid, HA, in aqueous solution. HA What happens to the HA molecules in solution?

  9. 100% dissociation of HA HA H+ Strong Acid A- Would the solution be conductive?

  10. Partial dissociation of HA HA H+ Weak Acid A- Would the solution be conductive?

  11. HA  H+ + A- HA H+ Weak Acid A- At any one time, only a fraction of the molecules are dissociated.

  12. Strong and Weak Acids/Bases Strong acids/bases – 100% dissociation into ions HClNaOH HNO3KOH H2SO4 Weak acids/bases – partial dissociation, both ions and molecules CH3COOHNH3

  13. pH Scale • pHis a measure of how acidic or basic a solution is. • The pH scale ranges from 0 to 14. • Acidic solutions have pH values below 7 • A solution with a pH of 0 is very acidic. • A solution with a pH of 7 is neutral. • Pure water has a pH of 7. • Basic solutions have pH values above 7.

  14. pH Scale • A change of 1 pH unit represents a tenfold change in the acidity of the solution. • For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic.

  15. 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.

  16. Acid – Base reactions • Each salt listed in this table can be formed by the reaction between an acid and a base.

  17. Bronsted-Lowry Model acid: anything that donates a [H+] (proton donor) base: anything that accepts a [H+] (proton acceptor) acid + base <=> acid + base HNO2 + H2O <=> NO2- + H3O+ Each acid has a conjugate base and each base has a conjugate acid. These conjugate pairs only differ by a proton. In this example: HNO2 is the acid, H2O is the base, NO2- is the conj. base, and H3O+ is the conj. acid. The Trick- Pick a compound on the left side of the equation. Find the similar compound on the other side of the reaction. The species with 1 more Hydrogen is the acid, the one with less is the base. HNO2 <=> NO2- or H2O <=> H3O+ So HNO2 is the acid. So H3O+ is the acid.

  18. Past Regents Questions According to one acid-base theory, water acts as an acid when an H2O molecule (1) accepts an H+ (3) accepts an H- (2) donates an H+ (4) donates an H- An acid can be defined as an (1) H+ acceptor (3) OH- acceptor (2) H+ donor (4) OH- donor

  19. AUTOIONIZATION of WATER Water is Amphiprotic H2O(l) + H2O(l) <==> H3O+(aq) + OH¯(aq)

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