Double Displacement (Exchange or Metathesis) Reactions Practicum Part I: Instructions: Write the molecular, complete ionic and net ionic equations for every one of the following reactions. If a reaction does not happen, simply write NR on the side of the products. 1. Aqueous sodium hydroxide and silver nitrate NaOH (aq) AgNO 3 (aq) NaNO 3 (aq) AgOH (s) Na (aq) OH (aq) OH (aq) Ag (aq) Ag (aq) AgOH (s) NO 3 (aq) Na (aq) NO 3 (aq) AgOH (s) The precipitate is brown. Note: silver hydroxide turns into silver oxide: 2 AgOH (s) Ag 2 O (s) H 2 O (l) 2. Aqueous sodium hydroxide and aqueous copper sulfate 2 NaOH (aq) CuSO 4 (aq) Na 2 SO 4 (aq) Cu(OH) 2 (s) 2 Na (aq) 2 OH (aq) 2 OH (aq) Cu 2 2 2 (aq) SO 4 (aq) 2 Na (aq) SO 4 (aq) Cu(OH) 2 (s) Cu 2 (aq) Cu(OH) 2 (s) A blue gelatinous precipitate of copper hydroxide, Cu(OH) 2 (s) is produced. 3. Aqueous potassium iodide and aqueous lead nitrate 2 KI (aq) Pb(NO 3 ) 2 (aq) 2 KNO 3 (aq) PbI 2 (s) 2 K (aq) 2 I (aq) 2 I (aq) Pb 2 (aq) PbI 2 (s) Pb 2 (aq) 2 NO 3 (aq) 2 K (aq) 2 NO 3 (aq) PbI 2 (s) A bright yellow precipitate of lead iodide, PbI 2 (s) is produced. 4. Aqueous potassium iodide and aqueous mercury (II) nitrate 2 KI (aq) Hg(NO 3 ) 2 (aq) HgI 2 (s) 2 KNO 3 (aq) 2 K (aq) 2 I (aq) 2 I (aq) Hg 2 (aq) 2 NO 3 (aq) 2 K (aq) 2 NO 3 (aq) HgI 2 (s) Hg 2 (aq) HgI 2 (s) A bright orange precipitate of mercury iodide, HgI 2 (s) is produced. Note: This is an unusual reaction as the precipitate dissolves in excess iodide solution and disappears as a complex ion is formed. 1
5. Aqueous potassium iodide and aqueous silver nitrate KI (aq) AgNO 3 (aq) AgI (s) KNO 3 (aq) K (aq) I (aq) I (aq) Ag (aq) Ag (aq) AgI (s) NO 3 (aq) K (aq) NO 3 (aq) AgI (s) A yellow white precipitate of silver iodide, AgI (s) is produced. 6. Aqueous sodium chloride and aqueous silver nitrate NaCl (aq) AgNO 3 (aq) NaNO 3 (aq) AgCl (s) Na (aq) Cl (aq) Cl (aq) Ag (aq) Ag (aq) AgCl (s) NO 3 (aq) Na (aq) NO 3 (aq) AgCl (s) Note: Exposure of AgCl (s) to UV light from the sun results in the decomposition of this compound. Black metallic silver is produced. 2 AgCl (s) 2 Ag (s) Cl 2 (g) 7. Aqueous mercury (II) nitrate and aqueous potassium flouride Hg(NO 3 ) 2 (aq) 2 KF (aq) HgF 2 (s) 2 KNO 3 (aq) Hg 2 (aq) 2 NO 3 (aq) 2 K (aq) 2 F (aq) HgF 2 (s) 2 K (aq) 2 NO 3 (aq) Hg 2 (aq) 2 F (aq) HgF 2 (s) An orange brown precipitate of mercury(ii) fluoride, HgF 2 (s) is produced. 8. Aqueous copper (II) sulfate and potassium iodide CuSO 4 (aq) 2 KI (aq) CuI 2 (s) K 2 SO 4 (aq) Cu 2 2 2 (aq) SO 4 (aq) 2 K (aq) 2 I (aq) CuI 2 (s) 2 K (aq) SO 4 (aq) Cu 2 (aq) 2 I (aq) CuI 2 (s) An olive green precipitate of copper iodide, CuI 2 (s) is produced. 2
9. Aqueous mercury (II) nitrate and aqueous potassium sulfide Hg(NO 3 ) 2 (aq) K 2 S (aq) HgS (s) 2 KNO 3 (aq) Hg 2 (aq) 2 NO 3 (aq) 2 K (aq) S 2 (aq) HgS (s) 2 K (aq) 2 NO 3 (aq) Hg 2 (aq) S 2 (aq) HgS (s) A black precipitate of mercury(ii) sulfide, HgS (s) is produced. 10. Aqueous silver nitrate and aqueous potassium chromate 2 AgNO 3 (aq) K 2 CrO 4 (aq) Ag 2 CrO 4 (s) 2 KNO 3 (aq) 2 Ag (aq) 2 Ag (aq) 2 NO 3 (aq) 2 CrO 4 (aq) 2 K (aq) Ag 2 CrO 4 (s) 2 CrO 4 (aq) Ag 2 CrO 4 (s) 2 K (aq) A red-brown precipitate of silver chromate, Ag 2 CrO 4 (s) is produced. 11. Aqueous mercury (II) sulfate and aqueous sodium carbonate 2 NO 3 (aq) HgSO 4 (aq) Na 2 CO 3 (aq) HgCO 3 (s) Na 2 SO 4 (aq) Hg 2 2 2 2 (aq) SO 4 (aq) 2 Na (aq) CO 3 (aq) HgCO 3 (s) 2 Na (aq) SO 4 (aq) Hg 2 2 (aq) CO 3 (aq) HgCO 3 (s) A yellow-brown precipitate of mercury (II) carbonate, HgCO 3 (s) is produced. 12. Aqueous manganese(ii) chloride and aqueous sodium hydroxide MnCl 2 (aq) 2 NaOH (aq) Mn(OH) 2 (s) 2 NaCl (aq) Mn 2 (aq) 2 Cl (aq) 2 Na (aq) 2 OH (aq) Mn(OH) 2 (s) 2 Na (aq) 2 Cl (aq) Mn 2 (aq) 2 OH (aq) Mn(OH) 2 (s) A white precipitate of manganese (II) hydroxide, Mn(OH) 2 (s) is produced. 13. Aqueous silver perchlorate and aqueous ammonium acetate AgClO 4 (aq) NH 4 C 2 H 3 O 2 (aq) NR (No reaction, both products are soluble. See below.) AgClO 4 (aq) NH 4 C 2 H 3 O 2 (aq) AgC 2 H 3 O 2 (aq) NH 4 ClO 4 (aq) 3
Part II: The following double displacement reactions involve the presence of acids and/or solids, and the product may not be a solid; however, since one of the reactants is present in aqueous solution, you can also write the molecular, complete ionic and net ionic equations (just keep in mind that certain compounds present do not dissociate). 14. Aqueous lead (II) chloride and sulfuric acid PbCl 2 (aq) H 2 SO 4 (aq) PbSO 4 (s) HCl (aq) Pb 2 2 (aq) 2 Cl (aq) 2 H (aq) SO 4 (aq) PbSO 4 (s) 2 H (aq) 2 Cl (aq) Pb 2 2 (aq) SO 4 (aq) PbSO 4 (s) Note: there is a strong acid present, but it dissociates completely. A white precipitate of lead (II) sulfate, PbSO 4 (s) is formed (this solid is also formed by a different reaction at the electrodes on car batteries). 15. Solid zirconium (IV) hydroxide and nitric acid Zr(OH) 4 (s) 4 HNO 3 (aq) Zr(NO 3 ) 4 (aq) 4 H 2 O (l) This is a neutralization reaction. Zr(OH) 4 (s) 4 H (aq) Zr(OH) 4 (s) 4 H (aq) 4 NO 3 (aq) Zr (aq) 4 4 H 2 O (l) Zr (aq) 4 4 NO 3 (aq) 4 H 2 O (l) Note: Water is the product, but is a molecular compound and it does not dissociate; therefore is present in all eqs. 16. Aqueous sodium sulfite and hydrochloric acid Na 2 SO 3 (aq) 2 HCl (aq) 2 NaCl (aq) H 2 SO 3 (aq) 2 NaCl (aq) SO 2 (g) H 2 O (l) A gas forming reaction. 2 Na (aq) 2 SO 3 (aq) 2 SO 3 (aq) 2 H (aq) 2 H (aq) 2 Cl (aq) SO 2 (g) H 2 O (l) 2 Na (aq) 2 Cl (aq) SO 2 (g) H 2 O (l) Note: Sulfur dioxide and water are molecular compounds and they do not dissociate. 17. Aqueous ammonium carbonate and sulfurous acid (NH 4 ) 2 CO 3 (aq) H 2 SO 3 (aq) (NH 4 ) 2 SO 3 (aq) H 2 CO 3 (aq) (NH 4 ) 2 SO 3 (aq) CO 2 (g) H 2 O (l) 2 NH 4 (aq) 2 CO 3 (aq) 2 CO 3 (aq) 2 H 2 SO 3 (aq) SO 3 (aq) H 2 SO 3 (aq) 2 NH 4 (aq) CO 2 (g) H 2 O (l) 2 SO 3 (aq) CO 2 (g) H 2 O (l) Note: Another gas forming reaction. Notice how sulfurous acid appears in all equations since it is a weak acid and it does not dissociate completely. 4
18. Aqueous copper(ii) nitrate and aqueous sulfuric acid Cu(NO 3 ) 2 H 2 SO 4 (aq) NR (No reaction, both products are soluble. See below.) Cu(NO 3 ) 2 H 2 SO 4 (aq) CuSO 4 (aq) HNO 3 (aq) 19. Acetic acid and aqueous barium hydroxide 2 CH 3 COOH (aq) Ba(OH) 2 (aq) Ba(CH 3 COO) 2 (aq) 2 H 2 O (l) This is a neutralization reaction. 2 CH 3 COOH (aq) Ba 2 (aq) 2 OH (aq) Ba 2 (aq) 2 CH 3 COO (aq) 2 H 2 O (l) 2 CH 3 COOH (aq) 2 OH (aq) 2 CH 3 COO (aq) 2 H 2 O (l) Note: Acetic acid is a weak acid (weak electrolyte) and does not dissociate completely in solution. 20. Aqueous sodium sulfide and phosphoric acid 3 Na 2 S (aq) 2 H 3 PO 4 (aq) 2 Na 3 PO 4 (aq) 3 H 2 S (g) Gas forming reaction. 6 Na (aq) 3 S 2 (aq) 3 S 2 (aq) 2 H 3 PO 4 (aq) 6 Na (aq) 3 2 H 3 PO 4 (aq) 2 PO 4 (aq) 3 H 2 S (g) 3 2 PO 4 (aq) 3 H 2 S (g) Note: Phosphoric acid is a weak acid and does not dissociate completely in water. H 2 S (g) is insoluble in water. The first 10 problems of this handout were taken from www.chemicalformula.org with some minor corrections and editing. 5