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HL Acids and Bases

HL Acids and Bases. Review for test. What are the 3 theories of acids and bases? Lavoisier Arrhenius Br Ø nsted -Lowry Lewis. HL Acids and bases. What are conjugate pairs? They differ by one proton or a H+. HL Acids and bases. What are the basic properties of acids and bases?

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HL Acids and Bases

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  1. HL Acids and Bases Review for test

  2. What are the 3 theories of acids and bases? • Lavoisier • Arrhenius • BrØnsted-Lowry • Lewis HL Acids and bases

  3. What are conjugate pairs? • They differ by one proton or a H+. HL Acids and bases

  4. What are the basic properties of acids and bases? • React differently with indicators. • Acids react with metals, bases, carbonates. • They can be strong or weak. • Low pH or high pH. HL Acids and bases

  5. How do we use pH and properties of water in calculations? • pH = -log[H+] pOH = -log[OH-] • Kw = [H+] [OH-] • Kw has different values depending on temperature. • The concentrations are inversely related. • What is the pH of blood that has 4.60 x 10-8 H+ concentration at 25º C? (Kw = 1x10-14) HL Acids and bases

  6. How do pH and pOH relate? • pH + pOH = 14.00 at 25º C. • pH and pOH can be found from concentrations of strong acids and bases • Ka is acid dissociation constant. • How is it different for strong and weak? HL Acids and bases

  7. What is the Ka of .01 M ethanoic acid with a pH of 3.4? • pH = -log [H+] • .01 – 4 x10-4 • Acid dissociation equation. • How about .75 M with a Ka of 1.8 x 10-5 has what pH? HL Acids and bases

  8. What are pKa and pKb? • These are negative logs of base 10 of Ka and Kb. • This gives positive values with no units. • Ka and pKa have inverse relationship (b also). • A change in one unit of pKa represents 10 the change in Ka (b also). • They are all still temperature related. HL Acids and bases

  9. What is the relationship between Ka and Kb and pKa and pKb? • Ka x Kb = [H+] [OH-] = Kw • pKa + pKb = pKw • pKa + pKb = 14 at 25C HL Acids and bases

  10. What are buffer solutions? • Buffers resist change in pH (pOH) with addition of small amounts of acid or base. • Acidic buffers are a weak acid and salt of weak acid and strong base. • Basic buffers are a weak base and salt of weak base with a strong acid. • They act on LeChatlier’sprinciple. HL Acids and bases

  11. How do we find the pH of a buffer solution? • Henderson-Hasselbalch equation • pH = pKa + log [salt]/[acid] • pOH = pKb + log [salt]/[base] • What is the pH of 25 mL of ethanoic acid and sodium ethanote with a Ka of 1.8 x 10-5? HL Acids and bases

  12. What is salt hydrolysis? • All acid base reactions create salts (cation from base and anion from acid). • If there is a weak acid, the anion is a strong enough that can it hydrolyse water releasing OH. • If there is a weak base and the cation is a nonmetal, it is able to hydrolyse water relasing H. • If the metal is small with a decent charge density, it acts like a ligand complex and takes OH out of the solution. (Be, Al, Fe) HL Acids and bases

  13. What is titration? • It is a controlled acid base neutralization reaction trying to find the equivalence point. • This is used to find the concentration of an unknown with a known amount of a known concentration. HL Acids and bases

  14. What are titration curves? HL Acids and bases

  15. What are indicators? • They are sensitive to changes in pH. • They change colors at specific pH’s. • Change color when pKa = pH. • This is the end point. • Used to find equivalence points in titrations. HL Acids and bases

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