21 acids + bases

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  • http://www.youtube.com/watch?v=5p540KucRc8 penny hydrochloric acid http://www.youtube.com/watch?v=oLZB0sneSQE penny HCl http://www.youtube.com/watch?v=wmvMdtIM1aA penny acid
  • http://www.youtube.com/watch?v=m55kgyApYrY
  • 21 acids + bases

    1. 1. ACIDS + BASES
    2. 2. ACIDS• Properties: (other than tasting sour and beingcorrosive)1) React with metals2) React with carbonates3) Conduct electricity4) Turn blue litmus paper red5) Neutralize basesACIDS ARE CORROSIVE
    3. 3. 1) ACIDS REACT WITH METALSIf you swallowed a penny,what would happen?(DON’T TRY THIS AT HOME!!!)
    4. 4. 1) ACIDS REACT WITH METALS2HCl(aq) + Zn(s)  H2(g) + ZnCl2(aq)
    5. 5. 2) ACIDS REACT WITH CARBONATESWhat happens when you put baking soda(sodium bicarbonate) into vinegar?HC2H3O2(aq) + NaHCO3(aq)  CO2(g) + H2O(l) + NaC2H3O2(aq)
    6. 6. 3) ACIDS CONDUCT ELECTRICITYAcids are made of ions, so in water these ionsseparate and can conduct electricityHCl(aq)  H+(aq) + Cl-(aq)
    7. 7. IONIZATION IN WATERH+Cl-H+Cl-H+Cl-Strong acidsionize completelyin water, whileweak acids onlyionize slightly
    8. 8. NEGATIVELY-CHARGEDELECTRODEPOSITIVELY-CHARGEDELECTRODEIONIZATION IN WATERH+Cl-H+Cl-H+Cl-H+Cl-- +
    9. 9. 4) ACIDS TURN BLUE LITMUS PAPER REDBlue litmus paper is an indicator and turns red whenit touches acid
    10. 10. 5) ACIDS NEUTRALIZE BASESAcids can neutralize bases, so adding an acid to abase can eliminate their corrosivenessHCl(aq) + NaOH(aq)  H2O(l) + NaCl(aq)Hydrochloric acid + sodium hydroxide  water + salt (sodium chloride)Corrosive + corrosive  non-corrosive + non-corrosive
    11. 11. BASESProperties: (other than tasting bitter, feeling slippery)1) Conduct electricity2) Turn red litmus paper blue3) Neutralize acidsBASES ARE CAUSTIC
    12. 12. 1) BASES CONDUCT ELECTRICITYBases are made of ions, so in water these ionsseparate and can conduct electricityNaOH(aq)  Na+(aq) + OH-(aq)
    13. 13. 2) BASES TURN RED LITMUS PAPER BLUERed litmus paper is an indicator and turns blue whenit touches base
    14. 14. 3) BASES NEUTRALIZE ACIDSBases can neutralize acids, so adding a base to an acid caneliminate their corrosivenessExample: Antacids to neutralize stomach acid2HCl(aq) + CaCO3(aq)  CaCl2(aq) + H2CO3(aq)H2CO3(aq)  H2O(l) + CO2(g)
    15. 15. HOW TO MAKE ACIDS + BASESACIDS:1) Non-metal + oxygen  non-metal oxide2) Non-metal oxide + water  ACID!EXAMPLE:N2 + 2O2  2NO2NO2 + H2O  HNO3BASES:1) Metal + oxygen  Metal oxide2) Metal oxide + water  BASE!EXAMPLE:Mg + O2  MgOMgO + H2O  Mg(OH)2
    16. 16. ACID-BASE INDICATORSIndicators change color depending on whether a substance isacidic or basic
    17. 17. pH ScaleFrom 1 to 14, with 7 being NEUTRAL
    18. 18. Arrhenius Theory of Acids and BasesAn acid is a substance that dissociates inwater to produce one or more hydrogenions (H+)ex. HBr(aq)  H+(aq) + Br-(aq)A base is a substance that dissociates inwater to form one or more hydroxide ions(OH-)ex. LiOH(aq)  Li+(aq) + OH-(aq)
    19. 19. Arrhenius Theory of Acids and BasesMy theory has alimitation…HBr(aq)  H+(aq) + Br-(aq)This reaction takes place in water!Without water, acid properties andreactions can’t exist.A hydronium ion is actuallyproduced (H3O+) to enable theeffects of water.HBr(aq) + H2O(l)  H3O+(aq) + Br-(aq)Arrhenius’s theorydoes not account forthe hydronium ion
    20. 20. Arrhenius Theory of Acids and Bases…more like 2limitations…NH3(aq) is a baseand does NOT have OH!!!!Actual reaction:NH3(aq) + H2O(l)  NH4+(aq) + OH-(aq)Arrhenius’s theory does not account forbases without OH groups
    21. 21. Brønsted-Lowry Theory of Acids and BasesAn acid is asubstance from whicha proton (H+ion) canbe removedA base is a substancethat can remove aproton (H+ion) froman acid
    22. 22. Brønsted-Lowry Theory of Acids and BasesH2O(l) + HCl(aq)  H3O+(aq) + Cl-(aq)Two molecules or ions that are related by the transfer of aproton are called a conjugate acid-base pairConjugate acid-base pair
    23. 23. Brønsted-Lowry Theory of Acids and BasesHBr(g) + H2O(l)  H3O+(aq) + Br-(aq)Examples of conjugate acid-base pairsConjugate acid-base pairConjugate acid-base pair
    24. 24. Brønsted-Lowry Theory of Acids and BasesNH3(g) + H2O(l)  NH4+(aq) + OH-(aq)Examples of conjugate acid-base pairsConjugate acid-base pairConjugate acid-base pair
    25. 25. Strong and Weak AcidsStrong acid/base: dissociates completely in waterExamples: HCl, H2SO4 NaOH, Ba(OH)2Weak acid/base: dissociates very slightly in waterExamples: CH3OOH (acetic acid) NH3Conjugate acid-base pairConjugate acid-base pair Reversible…at equilibrium
    26. 26. Strong and Weak AcidsMonoprotic acid: Acid only has one hydrogen ionEx: HClDiprotic acid: Acid has two hydrogen ionsEx: H2SO4Triprotic acid: Acid has three hydrogen ionsEx: H3PO4ACIDS
    27. 27. Strong and Weak AcidsLooking at a triprotic acid…H3PO4First ion dissociates: H3PO4(aq) + H2O(l) H3O+(aq) + H2PO4-(aq)Second ion dissociates: H2PO4-(aq) + H2O(l) H3O+(aq) + HPO42-(aq)Third ion dissociates: HPO42-(aq) + H2O(l) H3O+(aq) + PO43-(aq)STRONGEST acid (easiest to dissociate)WEAKEST acid (hardest to dissociate)ACIDS
    28. 28. If the pH is greater than 7,then the substance is basicIf the pH is less than 7, thenthe substance is acidicNEUTRALPower of Hydrogen (pH)
    29. 29. Power of Hydrogen (pH)H2O(l) + H2O(l) H3O+(aq) + OH-(aq)[H3O+] = [OH-] = 1.0 x 10-7mol/LIn a neutral solution at 25ºC…Concentration of H3O+Concentration of OH-pHNegativelogarithm of…Or-logConcentrationof H3O+ions(in mol/L)Or[H3O+]
    30. 30. Power of Hydrogen (pH)Therefore pH of water = -log [H3O+]= -log [1.0x10-7]= -(-7.00)= 7.00
    31. 31. Power of Hydrogen (pH)pH = - log [H3O+]pOH = - log [OH-][H3O+] = 10 –pH[OH-] = 10-pOHpH + pOH = 14Formulae involving pH:
    32. 32. Power of Hydrogen (pH)pOH = -log [OH-]= -log [3.8x10-3]= 2.42pH = 14 – pOH= 14 – (2.42)= 11.58= 12Calculate the pH of a solution with [OH-] = 3.8x10-3mol/LHOMEWORK: Page 393 #8, 9
    33. 33. CALCULATIONS INVOLVINGNEUTRALIZATION REACTIONSStoichiometry calculations:1) Write the balanced chemical reaction2) Convert all measurements to moles (if you can)3) Work with molar ratios to find out how much an acid is neededto neutralize a given amount of base, or vice versa.HCl(aq) + NaOH(aq)  H2O(l) + NaCl(aq)For example:How many moles of HCl would you need to neutralize 2 moles of NaOH?ANSWER: 2 moles of HCl
    34. 34. CALCULATIONS INVOLVINGNEUTRALIZATION REACTIONSWhat volume of 0.250 mol/L H2SO4(aq) is needed to reactcompletely with 37.2mL of 0.650mol/L KOH(aq)?
    35. 35. CALCULATIONS INVOLVINGNEUTRALIZATION REACTIONSWhat volume of 0.250 mol/L H2SO4(aq) is needed to reactcompletely with 37.2mL of 0.650mol/L KOH(aq)?H2SO4(aq) + 2KOH(aq) 2H2O(l) + K2SO4(aq)Step 1: Write the balanced chemical reactionStep 2: Convert everything to molesnKOH = C x V= (0.650mol/L) x (0.0372L)= 0.02418mol KOHStep 3: Work with molar ratios1mol H2SO4 = x2mol KOH 0.02418mol KOHx = 0.01209mol H2SO4NOT DONE YET! Need to solve for volume of H2SO4
    36. 36. CALCULATIONS INVOLVINGNEUTRALIZATION REACTIONSWhat volume of 0.250 mol/L H2SO4(aq) is needed to reactcompletely with 37.2mL of 0.650mol/L KOH(aq)?V = n/C= (0.01209mol)/(0.250mol/L)= 0.04836L H2SO4Therefore the volume of H2SO4 needed is 48.4mLHOMEWORK: Page 398 #13 + Page 406 #15
    37. 37. New Acid-Base TheoryNew Acid-Base Theory
    38. 38. Lewis Acids and BasesLewis Acids and BasesIdentify the acids and bases.H2SO3(aq) + Ca(OH)2(aq)  CaSO3(s) + 2 H2OIdentify the acid and base.CaO(s) + SO2(g)  CaSO3(s)Are the two reactions the same?acid baseLewis acidLewis base
    39. 39. Lewis Acids and BasesLewis Acids and BasesNot all acid-base reactions involve protontransfer.acid – chemical substance that can accept apair of electrons to form a covalent bondbase – chemical substance that can donate apair of electrons to form a covalent bondneutralization – formation of a covalent bondbetween an acid and base reactant
    40. 40. Example #1Example #1a) H+(aq) + OH-(aq) <===> H2O(l)b) NH3 + BCl3  ?Lewis acid Lewis baseLewis acidLewis baseBCl3:NH3adduct: often formed between Lewis acids and bases, resultingin a single product containing all atoms of all components.
    41. 41. ExamplesExamplesc) sulfur dioxide + oxide ion  sulfite iond) Identify the Lewis acid and base given:OH-+ CO2  HCO3-SO2 + O2- SO32-Lewis acid Lewis baseLewis acidLewis base

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