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Acids Lesson 20 Subtle Items. Subtle Acid Items 1. Weak bases neutralize a strong acid as well as a strong base would. HCl + NaOH HCl + HCO 3 -. → NaCl + HOH. → H 2 CO 3 + Cl -. Both reactions go to completion because of the strong acid. 2. H 3 BO 3 H 2 CO 3 HCl .
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Acids Lesson 20 Subtle Items
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.
2. H3BO3 H2CO3 HCl triprotic H3BO3⇌ H+ + H2BO3- diprotic H2CO3 ⇌ H+ + HCO3- monoprotic HCl → H+ + Cl- Only lose one proton when in water!
Which neutralizes more NaOH? H3BO3 or HCl? H3BO3 + 3NaOH→ Na3BO3 + 3HOH HCl+1NaOH → NaCl + HOH
3. Which determines acid strength? Molarity Ka is concentration is strength as indicated in the acid chart
4. Which determines the pH = -Log[H+] Ka determines the [H+] Molarity determines the [H+] Temperature affects the Ka
5. Pick the best conductor. 1 M NaCN 0.1 M HCl 0.1 M KOH
6. Pick the worst conductor. NaOH HCl NaCN NH3 Good Conductors are….. Strong acids Strong Bases Soluble Salts
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]
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
9. What ions are in H2SO4 solution? H2SO4 → H+ + HSO4- HSO4-⇌ H+ + SO42- [ OH-] because it is in water!
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
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!
12. HCl Molarity pH 10 M -1 1 M 0 0.1M 1 2 0.01M 0.001M 3 0.0001M 4
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!
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!
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
16. Describe the buffer present in human blood. H2CO3 NaHCO3 17. What is stomach acid? HCl 18 . What is battery acid? H2SO4
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. 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. Write a reaction between NaHCO3 and NaHC2O4 HCO3- + HC2O4- H2CO3 + C2O42- ⇌ Are the reactants or products favoured? products
0.10 M Weak Acid 0.10 M Weak Base x2 x2 Kw = Ka = Kb = Ka 0.10 0.10