2. Acids & Bases

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Chemistry Flashcards on 2. Acids & Bases, created by John Rivada on 19/04/2019.
John Rivada
Flashcards by John Rivada, updated more than 1 year ago
John Rivada
Created by John Rivada over 5 years ago
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Resource summary

Question Answer
What is a Bronsted acid? Species having tendency to lose a proton
What is a Bronsted base? Species having tendency to accept a proton
What is the equation for pka/ka? **
Define amphoteric Compund that can be acid OR base
What must the Ka value be for an acid to be completely dissociated? Ka >= 10^6
Is the following reaction capable of happening? Why or why not? Yes! Because the pka of HBr is really low and pkb of acetic acid is really high I think?
What is a zwitterion? An ion with both positive and negative charges in the same molecule
If acid is weak, is pH high or low? high
If acid is strong, is pH high or low? low
If acid is strong, is pka high or low? low
If acid is weak, is pka high or low? high
If base is weak, is pH high or low? low
If base is strong, is pH high or low? high
If base is strong, is pka high or low? high
If base is weak, is pka high or low? low
Define pka and pkb pka = ability to lose proton pkb = ability to gain proton
**turn this into a question
Conjugate base is MORE stable than acid: strong or weak acid? Strong
Conjugate base is LESS stable than acid: strong or weak acid? Weak
What makes an anion/conjugate base stable? -Spread out/ diffuse charge -Charge on electronegative atom -Weak H-A bond
Conjugate acid is MORE stable than base: strong or weak base? strong
Conjugate acid is LESS stable than base: strong or weak base? weak
What makes a conjugate acid stable? -Delocalized/resonating positive charge -If base was negatively charged, charge was on an electropositive (C,H) or moderately electronegative and small element (N) -Strong H-A bond
Examples of HARD F-, Cl-, RO-, Li+, Mg2+, H+ Cu(II) Carbonyls Carbonyls of a,b unsaturated carbonyls Acid Chlorides Silicon O lone pair F lone pair
Common HARD reagents R-MgX R-Li LiAlH4 LiBH4 DIBAL
What is the full name and chemical structure for DIBAL What is its main use? diisobutyl aluminium hydride **use?
Examples of SOFT I-, RS-, RSe-, S2-, Br- Cu+, Hg+, Hg2+ RSH, R3P, alkenes, aromatics, alkenes of a,b-unsaturated carbonyls lonep airs on: S, P, Br, I
Common SOFT reagents R2CuLi R-Mgx Cu(i) salt as cat. H2 + cat. PD Rh Pt (CuH)6 R-I R-Br
Calculate Keq of the above equation. Is it a complete reaction? No! Keq is not >= 10^6
How do you calculate log Keq? Or just Keq? log(Keq) = pka product acid - pka reactant acid or Keq = ka product acid - ka reactant acid
Why is that H3O+ is strongest acid in water? Because pka = -1.74 Stronger acids just make more H3O+
True or false: do solvents affect pKa? True! Better solvent is at stabilizing the ions, the LOWER the pka
Pka? 0
Pka? 5
Pka? 5
Pka? 10
Pka? 10
Pka? 10
Pka? 10
Pka? 15
Pka? 15
Pka? 20
Pka? 25
Pka? 25
Pka? 35
Pka? 35
Pka of alkanes? 50
Pkb range of alkyl- and aryllithiums? ~48-53
Pkb of LDA? ~35
Does an EWG make a compound more or less acidic? More
Does an EDG make a compound more or less acidic? Less
Does hybridization make a compound more or less acidic? Ie is an alkyne more or less basic than an alkane? More
What is good about LDA Not a good nucleophile So its good when we need to deprotonate and avoid nucleophilic addition to a carbonyl
Mechanism of LDA formation?
Are alkali metal hydrides good nucleophiles? Good bases? Bad Nucleophiles but great bases
PKb of H-? ie Pka of H2? ~35-36
Pkb >= pka - 6 Equilibrium favours which direction? Favour starting materials ** double check this
What is an amidine? (chemical structure)
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