Example Answers (on handout) Soluble or Insoluble? 7. K 3 PO 4 Soluble 8. Fe 3 (PO 4 ) 2 Insoluble...
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Transcript of Example Answers (on handout) Soluble or Insoluble? 7. K 3 PO 4 Soluble 8. Fe 3 (PO 4 ) 2 Insoluble...
Example Answers (on handout)
Soluble or Insoluble?
7. K3PO4 Soluble
8. Fe3(PO4)2 Insoluble
9. PbCl2 Insoluble (exception)
10. FeSO4 Soluble
11. (NH4)2S Soluble (exception)12. PbS Insoluble
•LAB THIS WEEK- ANALYSIS OF SILVER GROUP IONS
•OWL HOMEWORK- NEW ASSIGNMENTS POSTED
•ACID-BASE, SOLUBILITY, NET IONIC EQUATIONS
Announcements
pH Review
What is the pH of a 0.25M solution of NaOH? pH + pOH = 14 pOH=-log[OH-]
NaOH is a strong base [NaOH]=[OH-]
pOH= -log[0.25]=0.602
pH= 14 - pOH = 14 = 0.602 = 13.4
What is the [H3O+] of this solution?
[H3O+] = 10-pH = log-1(-pH)
[H3O+] = 10(-13.4) = 3.98 x 10-14M
Conjugate Acid-Base Pairs
Anions of weak acids are weak bases Conjugate acids and conjugate bases Example:
CH3COOH = weak acid
CH3COO- = weak base
What would this look like in a reaction?
CH3COONa + HCl ?
Anions of strong acids are neutral
Weak Acid Weak Base
CH3COOH CH3COO-
NH4+ NH3
H2CO3 CO32-
H2C2O4 C2O42-
H2SO3 SO32-
H2S S2-
H3PO4 PO43-
HCN CN-
HF F-
NHO2 NO2-
HClO ClO-
Net Ionic Equations
1. Write all reactants as they exist in solution2. Identify acids and bases
Need both acid and base present Look for “hidden bases” (anions of weak acids)
3. Ions that form insoluble compounds will form precipitates
4. Look for known gas-forming reactions5. Write out the products as they exist in
solution6. Cancel spectator ions