CHEM 1001/CHM 1020/ Chm1025C/CHM1032C Name:__ ANSWERS______

Module Five Sample Pretest

Part H Double Replacement Reactions 20 points

Given the following Solubility Rules for Ionic Compounds:

Table 8.2 p212

Compounds containing the following ions are generally soluble in water:

1. Alkali metal ions and ammonium ions, Li⁺ , Na⁺ , K⁺ , NH₄⁺

2. Acetate ion, C₂H₃O₂^-

3. Nitrate ion, NO₃^-

4. Halide ions (X), Cl^- , Br^- , I^- (AgX, Hg₂X₂ , and PbX₂ are insoluble exceptions)

5. Sulfate ion, SO₄ ^2- (SrSO₄, BaSO₄ , and PbSO₄ are insoluble exceptions)

Compounds containing the following ions are generally insoluble in water:

6. Carbonate ion,CO₃^2- (see rule 1 exceptions which are soluble)

7. Chromate ion CrO₄^2- (see rule 1 exceptions which are soluble)

8. Phosphate ion PO₄^3- (see rule 1 exceptions which are soluble)

9. Sulfide ion, S^2- (CaS, SrS, BaS, and rule 1 exceptions are soluble in water)

10. Hydroxide ion, OH^- [ Ca(OH)₂ , Sr(OH)₂ , Ba(OH)₂ , and rule 1 exceptions are soluble)

Complete and balance the following reactions using the above solubility table (write no reaction or NR if both products are soluble or a covalent compounds is not formed)

ANSWERS:

1. 2 AlCl₃ (aq) + 3 K₂CO₃ (aq) -----> Al₂(CO₃)₃ ↓ + 6 KCl

2. 3 NiSO₄ (aq) + 2 Li₃PO₄ (aq) -----> Ni₃(PO₄)₂ ↓ + 3 Li₂SO₄ (aq)

3. NaCl (aq) + AgNO₃ (aq) -----> AgCl ↓ + NaNO₃ (aq)

(balanced)

4. H₂SO₄ (aq) + 2 NaOH (aq) -----> Na₂SO₄ (aq) + 2 HOH (l)

(water is molecular-so the equation goes to completion)

5. 2 H₃PO₄ (aq) + 3 Ba(OH)₂ (aq) -----> Ba₃(PO₄)₂ ↓ + 6 HOH (l)

(in addition to the precipitate, water is molecular-so the equation would also goes to completion because of neutralization)

Additional Suggested Homework: p222 Problems 73-76; 77-80