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Acids, Bases, and Salts Ch 15 & 16

Acids, Bases, and Salts Ch 15 & 16. Introduction to Acids and Bases.asx. TERM PROJECT. U:My VideosNew FolderSOS 2011.mov Flyers and Guidelines are posted on my.ccsd.net THIS IS an ALL or Nothing Grade! 100 for completion and meeting the deadline and 55 for not.

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Acids, Bases, and Salts Ch 15 & 16

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  1. Acids, Bases, and SaltsCh 15 & 16 Introduction to Acids and Bases.asx

  2. TERM PROJECT • U:\My Videos\New Folder\SOS 2011.mov • Flyers and Guidelines are posted on my.ccsd.net • THIS IS an ALL or Nothing Grade! • 100 for completion and meeting the deadline and 55 for not.

  3. Properties of Acids Ch 15.1 Properties of acids and bases.asx • Acid Property #1. The word acid comes from the Latin word acere, which means "sour." All acids taste sour. • Acid Property #2. In 1663, Robert Boyle wrote that acids would make a blue vegetable dye called "litmus" turn red. • Acid Property #3. Acids destroy the chemical properties of bases.

  4. Acid Property #4. Acids conduct an electric current. • Acid Property #5. Upon chemically reacting with an active metal, acids will evolve hydrogen gas (H2).

  5. Properties of Bases • Base Property #1. The word "base" has a more complex history and its name is not related to taste. All bases taste bitter. • Base Property #2. Bases are substances which will restore the original blue color of litmus after having been reddened by an acid. • Base Property #3. Bases destroy the chemical properties of acids.

  6. Base Property #4. Bases conduct an electric current. • Base Property #5. Bases feel slippery, sometimes people say soapy. This is because they dissolve the fatty acids and oils from your skin and this cuts down on the friction between your fingers as you rub them together.

  7. The Acid Base TheoryCh 15.2 • The three main theories regarding acids and bases are: 1. Arrhenius 2. Brønsted-Lowry 3. Lewis

  8. Svante Arrhenius (1859-1927) Arrhenius Acids.asx

  9. Svante Arrhenius • Swedish chemist (1859-1927) - Nobel prize winner in chemistry (1903) • one of the first chemists to explain the chemical theory of the behavior of acids and bases

  10. 1. Arrhenius Definition • Acids produce hydrogen ions (H1+) in aqueous solution. • Bases produce hydroxide ions (OH1-) when dissolved in water. • Limited to aqueous solutions. • Only one kind of base (hydroxides) • NH3 (ammonia) could be an Arrhenius base? NH4OH?

  11. Polyprotic Acids • Some compounds have more than 1 ionizable hydrogen. • HNO3 nitric acid - monoprotic • H2SO4 sulfuric acid - diprotic - 2 H+ • H3PO4 phosphoric acid - triprotic - 3 H+ • Having more than one ionizable hydrogen does not mean stronger!

  12. Johannes Bronsted / Thomas Lowry (1879-1947) (1874-1936) Bronsted Acids.asx

  13. 2. Brønsted-Lowry Definitions • Broader definition than Arrhenius • Acid is hydrogen-ion donor (H+ or proton); base is hydrogen-ion acceptor. • Acids and bases always come in pairs. • HCl is an acid. • When it dissolves in water, it gives it’s proton to water. • HCl(g) + H2O(l) H3O+ + Cl- • Water is a base; makes hydronium ion.

  14. Acids and bases come in pairs... Conjugate acid-bases.asx

  15. Acids and bases come in pairs... • A conjugate base is the remainder of the original acid, after it donates it’s hydrogen ion • A conjugate acid is the particle formed when the original base gains a hydrogen ion • Indicators are weak acids or bases that have a different color from their original acid and base

  16. Acids and bases come in pairs... • General equation is: • HA(aq) + H2O(l) H3O+(aq) + A-(aq) • Acid + Base Conjugate acid + Conjugate base • NH3 + H2O NH41+ + OH1- base acid c.a. c.b. • HCl + H2O H3O1++ Cl1- • acid base c.a. c.b. Amphoteric - acts as acid or base

  17. Bases and Conjugate Acid

  18. Strength Strong and weak acids.asx • Strong acids and bases are strong electrolytes • They fall apart (ionize) completely. • Weak acids don’t completely ionize. • Strength different from concentration • Strong-forms many ions when dissolved • Mg(OH)2 is a strong base- it falls completely apart when dissolved. • But, not much dissolves- not concentrated

  19. What about bases? • Strong bases dissociate completely. • Weak bases only slightly ionize in water

  20. Strength vs. Concentration • The words concentrated and dilute tell how much of an acid or base is dissolved in solution - refers to the number of moles of acid or base in a given volume • The words strong and weak refer to the extent of ionization of an acid or base • Is a concentrated weak acid possible?

  21. *HNO3 - nitric acid *HCl - hydrochloric acid*H2SO4- sulfuric acid *HClO4 - perchloric acid *HBr - hydrobromic acid*HI - hydroiodic acid Strong Acids

  22. Strong Bases *LiOH - lithium hydroxide*NaOH - sodium hydroxide*KOH - potassium hydroxide*RbOH - rubidium hydroxide*CsOH - cesium hydroxide*Mg(OH)2 - magnesium hydroxide*Ca(OH)2 - calcium hydroxide*Sr(OH)2 - strontium hydroxide*Ba(OH)2 - barium hydroxide

  23. Self-Ionization of Water H2O + H2O  H3O+ + OH-

  24. Kw – Ionization Constant for Water In pure water at 25 C: • Kw = (1 x 10-7)(1 x 10-7) = 1 x 10-14 [H3O+] = 1 x 10-7 mol/L [OH-] = 1 x 10-7 mol/L Kw is a constant at 25 C: Kw = [H3O+][OH-]

  25. pH Scale • The pH scale is a measure of hydronium ion (H3O+) concentration. • Hydronium ion concentration indicates acidity. • The higher the H3O+, the higher the acidity. pH scale in nature.asx

  26. pH Lab Instructions • Copy down the chart below on a separate sheet of paper. 10 Samples

  27. Calculating pH, pOH pH scale.asx pH = -log(H3O+) pOH = -log(OH-) Relationship between pH and pOH pH + pOH = 14 Finding [H3O+], [OH-] from pH, pOH [H3O+] = 10-pH [OH-] = 10-pOH

  28. pH and pOH • See Packet

  29. Calculator Functions • See Book page 488

  30. H+, OH-, and pH

  31. pH Scale

  32. Measuring pH with wide-range paper

  33. Narrow-Range pH Paper

  34. pH Indicators and theirranges

  35. ACID-BASE Equilibria • Ka =Acid- Ionization Constant- • Kb =Base Ionization Constant • Constant meaning the point at which equilibria is reached. • Weak Acid- Small constant value because of small dissociation. • Strong Acid- Large Constant value because of large dissociation.

  36. ACID-BASE EQULIBRIA CONT: • Steps to Acid- Base Equlibria problem. • 1. Write out acid/ base equation- • HA + H2O  H3O+ + A- • 2. Write out constant expresssion. • Kb/a=[H3O+ ] [A-] [HA-]

  37. ACID BASE STEPS: • Step 3: Remember : Concentration of H3O+ ion and the Conjugate base will have the same concentration values. • Ka = (X) (X) [conc] Step 4. Plug in values and solve.

  38. Ammonia is a weak base. If the initial concentration of ammonia is .150M and the equilibrium concentration of OH- is 1.6 x 10-3, calculate Kb for ammonia? • Step 1. Equation- NH3 + H2O -> NH4 + OH- • Step 2: Apply Kb expression- products over reactants. • Step 3:plug in and solve • Answer: 1.7 X 10-5

  39. 2.6 mol of a weak acid is added to 1.0 L of water. At equilibrium the concentration of H3O+ is .34M What is the Ka for the acid? • 5.1 e-2

  40. What is the pH of 1.0 X 10-3 M NaOH solution? • 11

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