Mini review for midterm 2 NB: This does not cover all material!

Units, Conversions, Powers of 10, Prefixes Errors: Sig Figs, Error propagation Statistics: Normal distribution, t-test, Q-test Equilibrium: Constant, K sp, K H, K w, separation by precipitation, acids & bases Titration:v e (very) Rough outline Part 1 See midterm 1 review

Acids & bases - buffers Acid-base titrations Spectrophotometry Beer’s Law Properties of light Atomic spectroscopy (very) Rough outline For Part 1 See midterm 1 review

EQUILIBRIUM NB: K = f(T) K ≠ f(concentartions)

SOLUBILITY PRODUCT Ksp COMMON ION EFFECT Ksp = [Ca 2+ ] 3 [PO 4 3- ] 2 = 1.0 x = (3x) 3 ( x) 2 = 1.0 x EQUILIBRIUM x  solubility (mols/L of Ca 3 (PO 4 ) that can disolve)

TITRATION STEP 1: reaction STEP 2: V e STEP 4: at equivalence STEP 5: after equivalence STOICHIOMETRY! STEP 3: before equivalence what part is left? all analyte consumed excess titrant

ACTIVITY

SOLUBILITY PRODUCT K sp GAS  SOLUTION K H WATERK W ACIDK a BASEK b EQUILIBRIUM

WATER EQUILIBRIUM K w pH EQUILIBRIUM

ACID – BASE EQUILIBRIUM

BUFFERS NB: Equal concentrations  pH = pK a (most effective buffer)

Weak acid With Strong base HA  H + + A - STEP 1: reaction STEP 2: V e # mols base added = # mols acid removed

Weak acid With Strong base STEP 3: before equivalence BUFFER! HA  H + + A - NB: at v = v e /2 concentrations are equal  pH = pK a !

Weak acid With Strong base STEP 3: before equivalence BUFFER! STEP 4: at equivalence A - + H 2 O  HA + OH - K b HA  H + + A - NB: What is pH at equivalence: for titration of strong acid with strong base? and for a weak acid with a strong base > or < 7?

Weak acid With Strong base STEP 3: before equivalence BUFFER! STEP 4: at equivalence A - + H 2 O  HA + OH - K b STEP 5: after equivalence excess OH - HA  H + + A -

Transmittance Absorbance Beer’s Law Spectrophotometry

ε depends on molecule wavelength

Spectrophotometry λν = c [3 x 10 8 m/s] E = h ν

Spectrophotometry

The fraction of atoms in the excited state is still less than 0.02%, but that fraction has increased by 100(1.74 – 1.67)/1.67 = 4%

Linewidth