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ACIDS AND BASES

ACIDS AND BASES. Chapter 8 - Honors. Properties of Acids and Bases – Journal 1. Read and highlight Sections 8.1-8.4 on the worksheet from the back table. Make vocabulary flashcards for Sections 8.3 & 8.4

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ACIDS AND BASES

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  1. ACIDS AND BASES Chapter 8 - Honors

  2. Properties of Acids and Bases – Journal 1 • Read and highlight Sections 8.1-8.4 on the worksheet from the back table. Make vocabulary flashcards for Sections 8.3 & 8.4 • I will be coming around with samples for you to taste. Classify each of the liquids as an Acid, Base or Neutral based on what you learn about the characteristics of acids and bases in your reading.

  3. Acids and Bases • Acids and Bases are Compounds that have very distinct properties. HCl + H2O  H3O 1+(aq) +Cl 1-(aq) NaOH(s) Na 1+(aq) + OH 1-(aq)

  4. WATER Before understanding Acids and Bases, you must understand water. • It is a polar molecule. Like a magnet. - - + +

  5. WATER • It is a polar molecule. WHY??? Oxygen pulls on the electrons more than Hydrogen does. Oxygen = Higher ionization energy. - - + +

  6. WATER Because water is POLAR (negative side and positive side), what types of compounds will it DISSOLVE easily? CHARGED - - + +

  7. Acids • Acids: compounds that IONIZE and produce HYDRONIUM IONS when dissolved in water. HCl + H20  H3O1+ +Cl1- • Written also as: HCl  H1+ +Cl1-

  8. Acids When HCl is put in water, a Hydronium ion, H3O1+ (hydrogen ion, H1+) is formed. Why might acids be referred to as “PROTON DONORS”?

  9. Acids: ionization Acids ARE “PROTON DONORS” http://www.learning.gov.sk.ca/branches/elearning/tsl/resources/subject_area/science/chem_30_resources/lesson_8/acids_and_bases.shtml

  10. Acids • Characteristics of Acids • Taste Sour • React Strongly with Metals and Carbonates (in soil and rocks) • Burn skin • Conduct electricity in water (electrolyte) • Turn blue litmus paper red

  11. Common Acids Acetic acid CH3COOH Vinegar Carbonic acid H2CO3 Carbonated beverages Hydrochloric acid HCI Digestive juices in stomach Nitric acid HNO3 Fertilizer production Phosphoric acid H3PO4 Fertilizer production Sulfuric acid H2SO4 Car batteries

  12. Bases • Bases: ionic compounds that DISSOCIATE and produce HYDROXIDE IONS when dissolved in water. • NaOH(s) Na 1+(aq) + OH 1-(aq)

  13. Bases Bases are Ionic compounds that break apart (dissociate) in water to form a negatively chargedhydroxide ion (OH 1-). Why might bases be referred to as “PROTON ACCEPTORS”? http://web.umr.edu/~gbert/ANIMATED/Asoly.HTML

  14. Bases http://www.learning.gov.sk.ca/branches/elearning/tsl/resources/subject_area/science/chem_30_resources/lesson_8/acids_and_bases.shtml Bases ARE “PROTON ACCEPTORS” http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/acm2s2_1.swf

  15. Bases • Characteristics of Bases • Taste bitter • Feel Slippery • Burn your Skin • Conduct electricity in water (electrolyte) • Turn red litmus paper blue

  16. Common Bases Aluminum hydroxide Al(OH)3 Deodorant, antacid Calcium hydroxide Ca(OH)2 Concrete, plaster Magnesium hydroxide Mg(OH)2 Antacid, laxative Sodium hydroxide NaOH Drain cleaner, soap production

  17. Strength of Acids and Bases Which would you say is MORE acidic: • battery acid • Or milk? WHY is battery acid MORE ACIDIC?

  18. Strength of Acids and Bases • MORE hydronium (H3O 1+)ions. • How many hydronium ions are in the strong acid? In the weak acid?

  19. Strength of Acids and Bases • Chemists use a number scale from 0 to 14 to describe the concentration (amount of) hydronium (H3O 1+)ions in a solution. • This is the pH Scale.

  20. Strength of Acids and Bases • The pH of a solution is a measure of the hydronium ion (H3O 1+)concentration.

  21. Strength of Acids and Bases • Neutral substances have a value of 7 • Their number of hydronium ions equal their number of hydroxide ions.

  22. Strength of Acids and Bases • Distilled water is neutral. • It’s hydronium ions equal it’s hydroxide ions This is because water ionizes slightly.

  23. Strength of Acids and Bases • Acids have a pH value of LESS THAN 7 • Bases have a pH value of MORE THAN 7 • Which are the strongest acids and bases? • Which are the weakest acids and bases? • What is NEUTRAL?

  24. Acids and Bases - JOURNAL • Fill in the Identifying Acids and Bases sheet.

  25. Strength of Acids and Bases What is the difference between the strong and the weak, regardless of concentration? Strong substances IONIZE/DISSOCIATE COMPLETELY.

  26. Strength of Acids and Bases How do you get strong and weak acids and bases? • STRONG ACIDS/BASES COMPLETELY IONIZE/DISSOCIATE • HCl + H2O H3O + + Cl – • Reaction only goes in one direction. • WEAK ACIDS/BASES DO NOT dissociate/ionize completely • NH3 + H2O NH4+ + OH – • Reaction goes in both directions. Not all of the compound ionizes. • http://www.mhhe.com/physsci/chemistry/chang7/esp/folder_structure/ac/m2/s1/acm2s1_1.htm

  27. If you multiplied this number by 100, what would be your chances of finding a hydronium ion in solution? • 100% • 10% • 1% • So, your chances get slimmer as the exponent gets LARGER. • The fewer the H3O 1+, the weaker the acid. If pH is the measure of hydronium ions, why are acids the lowest numbers? http://www.purchon.com/chemistry/acids.htm#animation

  28. Strength of Acids and Bases – Journal Fill in the Acids and Bases Practice Sheet.

  29. Reactions between Acids and Bases • When bases REACT with acids, the process is calledNEUTRALIZATION.

  30. Reactions between Acids and Bases • They react to form a salt and water(& HEAT) Hydrochloric Acid + Sodium Hydroxide Water + Table Salt HCl + NaOH  H2O + NaCl

  31. Common Salts Sodium chloride NaCl Food flavoring, preservative Sodium carbonate Na2CO3 Used to make glass Potassium chloride KCl Used as a salt substitute to reduce dietary intake of sodium Potassium iodide Kl Added to table salt to prevent iodine deficiency Magnesium chloride MgCl2 De-icer for roads Calcium carbonate CaCO3 Chalk, marble floors, and tables Ammonium nitrate NH4NO3 Fertilizer, cold packs

  32. Acids and Bases and Neutralization • One of the most important aspects of a living system is the amount of acidity or alkalinity

  33. NEUTRALIZATION: Why do we need to know? • Control of pH is very important • Control is accomplished with buffers

  34. NEUTRALIZATION: Why do we need to know? • Buffers neutralize small amounts of either an acid or base.

  35. NEUTRALIZATION: Why do we need to know? Alkalinity – the ability of a stream to neutralize acids.

  36. Properties of Acids and Bases – Journal 5 • Come in, take out your homework, and get your LAB sample. • Write an equation that shows NEUTRALIZATION. Include the names of the REACTANTS and PRODUCTS. • What is the range of the pH scale? The range for acids? Bases? Neutral? • What is the strongest Acid value? Base value? What would be a weak acid? Weak base?

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