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Flashcards in Acid and bases Deck (23)
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1
Q

Theory of acid and bases

A
  • Arhennius theory
  • Bronsted-lowry theory
  • Lewis theory
2
Q

Arhennius theory

A
  • Acid produces H+/H3O+ ions
  • Bases produces OH- ions
3
Q

Bronsted-lowry theory

A
  • An acid is a proton (hydrogen ion) donor.
  • A base is a proton (hydrogen ion) acceptor.
4
Q

Lewis theory

A
  • An acid is an electron pair acceptor.
  • A base is an electron pair donor.
5
Q

There isn’t an empty orbital anywhere on the HCl which can accept a pair of electrons.

Why, then, is the HCl a Lewis acid?

A
  • HCl is polar. Chlorine is more electronegative than hydrogen, leaving the hydrogen slightly positive and the chlorine slightly negative.
  • Lone pair on the nitrogen of an ammonia molecule is attracted to the slightly positive hydrogen atom
  • e- are slowly pushed towards chlorine, HCl bond breaks and dative/coordinate bond is formed
6
Q

pKa table

A
7
Q

Acid-Base reaction overview

A
  • The species which loses H+ is the acid
  • The species which gains H+ is the base
  • The conjugate base is what becomes of the acid after it loses H+
  • The conjugate acid is what becomes of the base after it gains H+
8
Q

What determines acidity?

A
  • any factor which stabilizes the conjugate base will increase the acidity.
  • any factor which destabilizes the conjugate base will decrease the acidity.
  • a roughly equivalent word for “stability” is “basicity
9
Q

What determines basicity?

A
  • Stabilizing a lone pair lowers the basicity;
  • Destabilizing the lone pair increases basicity.
10
Q

Acidity trend

  1. the lesser the charge, the better the acidity
A

All else being equal, the lower the charge density, the more stable a species is.

11
Q

Acidity trend

Polarizability

A
12
Q

Acidity trends

  1. Electron withdrawing groups
A
13
Q

orbitals

A
14
Q

Acidity trend

aromacity

A
15
Q

What makes a good leaving group?

A

Good leaving groups are weak bases.

16
Q

How do we know which are weak bases?

A
  • The stronger the acid, the weaker the conjugate base
  • the weaker the conjugate base, the better the leaving group
17
Q

pka table, handy guide to leaving group

A
18
Q

A leaving group is a nucleophile in reverse

A
19
Q

OH- is a bad leaving group

A
20
Q

OH- IN sn1 example

A
21
Q

OH- in SN2 example

A

conjugate acid will always be a better leaving group.

22
Q

Acids helps facillitates cleavage of ether

A
23
Q
A