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Acids Lesson 20 Subtle Items

This lesson explores the concepts of acid-base reactions, neutralization, acid strength, pH, conductivity, buffer solutions, and strong and weak acids and bases.

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Acids Lesson 20 Subtle Items

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  1. Acids Lesson 20 Subtle Items

  2. Subtle Acid Items 1.Weak basesneutralize a strong acid as wellas a strong basewould. HCl + NaOH HCl+ HCO3- → NaCl + HOH → H2CO3 + Cl- Both reactions go to completion because of thestrong acid.

  3. 2. H3BO3 H2CO3 HCl   triprotic H3BO3⇌ H+ + H2BO3- diprotic H2CO3 ⇌ H+ + HCO3- monoprotic HCl → H+ + Cl- Only lose one proton when in water!

  4. Which neutralizes more NaOH? H3BO3 or HCl?  H3BO3 + 3NaOH→ Na3BO3 + 3HOH HCl+1NaOH → NaCl + HOH

  5. 3. Which determines acid strength? Molarity Ka is concentration  is strength as indicated in the acid chart

  6. 4. Which determines the pH = -Log[H+] Ka determines the [H+]  Molarity determines the [H+]  Temperature affects the Ka 

  7. 5. Pick the best conductor. 1 M NaCN 0.1 M HCl 0.1 M KOH 

  8. 6. Pick the worst conductor. NaOH HCl NaCN NH3  Good Conductors are….. Strong acids Strong Bases Soluble Salts

  9. 1 mole H2CO3 and 1mole NaHCO3 are dissolved in • 0.5 L of water.   What kind of solution results in the above mixture? Buffer Write an equation for the equilibrium. H2CO3⇋ H+ + HCO3- Label each chemical species with a concentration. 2 M Low 2 M What limits the ability to buffer against acid? [HCO3-] What limits the ability to buffer against base? [H2CO3]

  10. 8. Acid Base   HF F- H3BO3 H2BO3- HCN CN- Put an asterisk next to the strongest acid and base What is the relationship between acid strength and strength of conjugate base? * * Inverse

  11. 9. What ions are in H2SO4 solution? H2SO4 → H+ + HSO4- HSO4-⇌ H+ + SO42- [ OH-] because it is in water!

  12. 10. Which titration will have the equivalence point with lowest conductivity? HCl + NaOH → H2SO4 + Ba(OH)2→ NaCl(aq)+HOH High Solubility BaSO4(s)+2HOH Low Solubility Lowest Conductivity

  13. 11. What is the best acid for titrating 0.10 MNH3? 0.00010 M HCl 0.10 M HF 6.0 M HCl 0.10 M HCl  Must be strong and about the same molarity!

  14. 12. HCl Molarity pH 10 M -1 1 M 0 0.1M 1 2 0.01M 0.001M 3 0.0001M 4

  15. 13. A 0.00010 M acid has a pH of 4.0. Is the acid strong or weak? • StrongpH = -Log[0.00010] = 4.0 • The pH is only at 1.0 M!

  16. 14. A 0.0010 M acid has a pH of 4.0. Is the acid strong or weak? • WeakpH = -Log[0.0010] = 3.0 • The pH is only at 1.0 M!

  17. 15. HInd ⇌ H+ + Ind- • It’s yellow in HCl and red in HCN • Assign each colour • Which is the stronger acid; HInd or HCN? • HCN + Ind- ⇌ HInd + CN- • What is favoured? • Reactants yellow red  

  18. 16. Describe the buffer present in human blood. H2CO3 NaHCO3 17. What is stomach acid? HCl 18 . What is battery acid? H2SO4

  19. 19. Match the Curve with the Reaction 0 30 60 pH 14 7 0 Volume 1.0 M NH3 added  A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH

  20. 20. Match the Curve with the Reaction 0 30 60 pH 14 7 0 Volume 1.0 M NH3 added A. 3HCl + Al(OH)3 → AlCl3 + 3HOH B. HCl + KOH → KCl + HOH C. HCN + KOH → KCN + HOH 

  21. 21. Write a reaction between NaHCO3 and NaHC2O4 HCO3- + HC2O4- H2CO3 + C2O42- ⇌ Are the reactants or products favoured? products

  22. 0.10 M Weak Acid 0.10 M Weak Base x2 x2 Kw = Ka = Kb = Ka 0.10 0.10

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