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

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Presentation on theme: "Mini review for midterm 2 NB: This does not cover all material!"— Presentation transcript:

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

2 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

3 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

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

5 SOLUBILITY PRODUCT Ksp COMMON ION EFFECT Ksp = [Ca 2+ ] 3 [PO 4 3- ] 2 = 1.0 x 10 -26 = (3x) 3 (0.10 + 2x) 2 = 1.0 x 10 -26 EQUILIBRIUM x  solubility (mols/L of Ca 3 (PO 4 ) that can disolve)

6 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

7 ACTIVITY

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

9 WATER EQUILIBRIUM K w pH EQUILIBRIUM

10 ACID – BASE EQUILIBRIUM

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

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

13 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 !

14 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?

15 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 -

16 Transmittance Absorbance Beer’s Law Spectrophotometry

17 ε depends on molecule wavelength

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

19

20 Spectrophotometry

21 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%

22 Linewidth


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