Acids
- All acids start with H
- Covalent bonds bcuz hydrogen bonds with nonmetals
- Can usually tell that is an acid b/c produces H+ in solution
Naming acids
- Binary: hydro___ic acid
- Polyatomic: NO hydro
○ -ate = __ic acid
○ -ite = __ous acid
Bases
- Ionic bonds because has cation with anion
- Can usually tell that is a base b/c produces OH- in solution
Naming Bases
- Name first element and end with hydroxide
Models of acids and bases
- At equilibrium:
○ There is a competition for H+ between H2O and A-
○ The stronger base controls direction → The direction of equilibrium depends on if the acid is weak or strong
■ If H2O is a stronger base than A-, (H2O attracts H+ more) → forward reaction favored → most of the acid dissolved will be in the ionized form
■ If A- is a much stronger base than H2O → reverse reaction favored → at equilibrium most of the acid will exist as HA
- Monoprotic acids: one acidic hydrogen
- Polyprotic acids: more than one acidic hydrogen which can donate to the solution
- Oxyacids: acidic hydrogen is attached to the oxygen of an ion
- Organic Acids: acids that contain carbon and usually a carboxyl group, generally very weak
Water as an Acid and a Base
- Amphoteric: it can behave either as an acid or a base (ex: water, HSO4-)
○ The species can both accept a proton to form its conjugate acid, and donate a proton to form a conjugate base
○ As an acid:
○ As a base:
- Water is amphoteric and autoionizes:
- For water only: [H+] = [OH-] = pH = pOH = at all temperatures → the two graphs will be the same & water is always neutral
The pH Scale
- As pH decreases, [H+] increases exponentially
○ pH changes by 1 for every power of 10 change in [H+]
- Sig Figs & pH: number of sig figs of molarity = number of decimal places in pH
○ Ex:
- Do not use pH as justification for if a solution is acidic or basic; instead say…
○ Neutral solution: [H+] = [OH-]
○ Acidic solution: [H+] > [OH-]
○ Basic solution: [H+] < [OH-]
Relationships (All on RFS)
○ P = (-) log of …
- (on RFS)
○ Remember that solids and liquids are not included; Kw value is temperature dependent
■ Ionization increases with increasing temperature (kW will be greater value)
- →Subtract 14 from pOH to find pH
- → Given any one of these → can find the other three
○ Higher H+ = Lower OH- = Lower pH = higher pOH