Monday, March 14, 2011

Acids & Bases

Strong Acids

Hydroiodic acid

HI

Hydrobromic acid

HBr

Hydrochloric acid

HCl

Perchloric acid

HClO4

Sulfuric acid

H2SO4

Nitric acid

HNO3

Strong Bases

Group 1 hydroxides

NaOH, LiOH, KOH

Group 1 oxides

Li2O, etc.

Some group 2 hydroxides

Ba(OH)2, Sr(OH)2, Ca(OH)2

Metal amides

NaNH2, LiNH2, Mg(NH2)2, Ca(NH2)2, etc.


- The conjugate base of a strong acid has no basic properties in water.
- The conjugate base of a weak acid is a weak base.

- The conjugate acid of a strong base has no acidic properties in water. For example, the conjugate acid of LiOH is Li+, which does not act as an acid in water.
- The conjugate acid of a weak base is a weak acid (and the weaker the base, the stronger the conjugate acid). For ex, the conjugate acid of NH3 is NH4+, a weak acid.

Amphoteric: can act as either an ACID or BASE. The conjugate base of a weak polyprotic (more than one H) acid is always amphoteric, because it can either donate or accept another proton.
- ex: H2CO3 à HCO3- à CO32-

Friday, March 4, 2011

Reaction Rate

1. the lower the activation energy, the faster the reaction rate
2. the greater the concentrations of the reactants, the faster the rate (more favorable collisions)
3. the higher the temperature of the reaction mixture, the faster the reaction rate


ΔG has no bearing on rate of the reaction!
Thermodynamic & Kinetic factors DO NOT AFFECT EACH OTHER!!!

Catalyst - lowers the activation energy of the rate-determining step (therefore the energy of the higher-energy transition state), remains UNCHANGED at the end of the rxn
***even though the catalyst MAY physically change in the middle...will always revert back for no net change
Rate Law - reactants of rate-determining step, NOT products...(previous post)...can only be determined EXPERIMENTALLY