1. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 1 Synthesis Reactions Type 1: A metal combines with a nonmetal to form a binary salt. Example: A piece of lithium metal is dropped into a container of nitrogen gas. 6Li (s) + N 2 (g) → 2Li 3 N (aq)

2. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 2 Synthesis Reactions Type 2: Metallic oxides and water form bases (metallic hydroxides). Example: Solid sodium oxide is added to water Na 2 O (s) + HOH (l) → 2NaOH (aq) Example: Solid magnesium oxide is added to water. MgO (s) + 2HOH (l) → Mg(OH) 2 (aq)

3. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 3 Synthesis Reactions Type 3: Nonmetallic oxides and water form acids. The nonmetal retains its oxidation number. Example: Carbon dioxide is bubbled in water. CO 2 (g) + H 2 O (l) → H 2 CO 3 (aq) Example: Dinitrogen pentoxide is bubbled in water. N 2 O 5 (g) + H 2 O (l) → 2HNO 3 (aq)

4. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 4 Synthesis Reactions Type 4: Metallic oxides and nonmetallic oxides form salts. Example: Solid sodium oxide is added to carbon dioxide. Na 2 O (s) + CO 2 (g) → Na 2 CO 3 (aq) Example: Solid calcium oxide is added to sulfur trioxide. CaO (s) + SO 3 (g) → CaSO 4 (aq)

5. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 5 Decomposition Reactions Type 1: Metallic carbonates decompose into metallic oxides and carbon dioxide Example: A sample of magnesium carbonate is heated. MgCO 3 (s) → MgO (s) + CO 2 (g)

6. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 6 Decomposition Reactions Type 2: Metallic chlorates decompose into metallic chlorides and oxygen. Example: A sample of magnesium chlorate is heated. Mg(ClO 3 ) 2 (aq) → MgCl 2 (aq) + 3O 2 (g)

7. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 7 Decomposition Reactions Type 3: Ammonium carbonate decomposes into ammonia, water, and carbon dioxide. Example: A sample of ammonium carbonate is heated. (NH 4 ) 2 CO 3 (aq)→ 2NH 3 (g) + H 2 O (l) + CO 2 (g)

8. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 8 Decomposition Reactions Type 4: Sulfurous acid decomposes into sulfur dioxide and water. Example: A sample of ammonium carbonate is heated. H 2 SO 3 (aq) → H 2 O (l) + SO 2 (g)

9. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 9 Decomposition Reactions Type 5: Carbonic acid decomposes into carbon dioxide and water. Example: A sample of carbonic acid is heated. H 2 CO 3 (aq) → H 2 O (l) + CO 2 (g)

10. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 10 Decomposition Reactions Type 6: A binary compound may break down to produce two elements. Example: Molten sodium chloride is electrolyzed. 2NaCl (l) → 2Na (s) + Cl 2 (g)

11. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 11 Decomposition Reactions Type 7: Hydrogen peroxide decomposes into water and oxygen. Example: 2H 2 O 2 (aq) → 2H 2 O (l) + O 2 (g)

12. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 12 Decomposition Reactions Type 8: Ammonium hydroxide decomposes into ammonia and water. Example: NH 4 OH (aq) → NH 3 (g) + HOH (l)

13. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 13 Single Replacement Type 1: Active metals replace less active metals from their compounds in aqueous solution. Example: Magnesium turnings are added to a solution of iron (III) chloride. 3Mg (s) + 2FeCl 3 (aq)→ 2Fe (s) + 3MgCl 2 (aq)

14. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 14 Single Replacement Type 2: Active metals replace hydrogen in water. Example: Sodium is added to water. 2Na (s) + 2HOH (l)→ 2NaOH (aq) + H 2 (g)

15. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 15 Single Replacement Type 3: Active metals replace hydrogen in acids. Example: Lithium is added to hydrochloric acid. 2Li (s) + 2HCl (aq) → 2LiCl (aq) + H 2 (g)

16. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 16 Single Replacement Type 4: Active nonmetals replace less active nonmetals from their compounds in aqueous solution. Example: Chlorine gas is bubbled into a solution of potassium iodide. Cl 2 (g) + 2KI (aq) → I 2 (g) + 2KCl (aq)

17. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 17 Single Replacement Type 5: If a less reactive element is combined with a more reactive element in compound form, their will be no resulting reaction. Example: Chlorine gas is bubbled into a solution of potassium iodide. Cl 2 (g) + KF (aq) → No Reaction Example: Zinc is added to a solution of sodium chloride. Zn (s) + NaCl (aq) → No Reaction

18. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 18 Double Replacement (Gas) Common Gases H2SH2SAny sulfide (salt of S 2- ) plus any acid form H 2 S (g) and a salt. CO 2 Any carbonate (salt of CO 3 2- ) plus any acid form CO 2 (g), HOH, and a salt SO 2 Any sulfite (salt of SO 3 2- ) plus any acid form SO 2 (g), HOH, and a salt. NH 3 Any ammonium salt (salt of NH 4 + ) plus any soluble strong hydroxide react upon heating to form NH 3 (g), HOH, and a salt.

19. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 19 Double Replacement (Gas) Example 1: The reaction of Na 2 SO 3 and HCl produces H 2 SO 3 : Na 2 SO 3 (aq) + 2HCl (aq) → H 2 SO 3 (aq) + 2NaCl (aq) Bubbling is observed in this reaction because the H 2 SO 3 (sulfurous acid) is unstable and immediately decomposes to give HOH and SO 2 gas: H 2 SO 3 (aq) → HOH (l) + SO 2 (g) The molecular equation for the overall or complete reaction, therefore, is: Na 2 SO 3 (aq) + 2HCl (aq) → HOH (l) + SO 2 (g) + 2NaCl (aq)

20. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 20 Double Replacement (Gas) Example 2: A typical reaction of a carbonate and an acid is: K 2 CO 3 (aq) + 2HNO 3 (aq) → HOH (l) + CO 2 (g) + 2KNO 3 (aq) Bubbling is also observed in this reaction. Theoretically H 2 CO 3, carbonic acid, is formed, but the acid is unstable and immediately decomposes to form carbon dioxide gas and water according to the following equation: H 2 CO 3 (aq) → HOH (l) + CO 2 (g)

21. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 21 Double Replacement (Gas) Example 3: Ammonium salts and soluble bases react as follows (particularly when the solution is warmed): NH 4 Cl (aq) + NaOH (aq) → NH 3 (g) + HOH (l) + NaCl (aq) The odor of ammonia gas is noted and moist blue litmus paper held near the mouth of the container will turn blue. Theoretically NH 4 OH, ammonium hydroxide, is produced (also known as ammonia water). The compound is unstable and decomposes into ammonia gas and water: NH 4 OH (aq) → NH 3 (g) + HOH (l)

22. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 22 Double Replacement (Gas) Example 4: The odor of rotten eggs and bubbling are noted when an acid is added to a sulfide. A typical reaction producing hydrogen sulfide gas is: FeS (s) + 2HCl (aq) → FeCl 2 (aq) + H 2 S (g)

23. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 23 Acid-Base Reactions Example 1: Hydrogen sulfide gas is bubbled through excess potassium hydroxide solution. H 2 S (g) + 2KOH (aq) → K 2 S (aq) + 2HOH (l)

24. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 24 Acid-Base Reactions If the base is in excess, all hydrogen ions will react with strong base to produce water. Example 2: Dilute sulfuric acid is reacted with excess sodium hydroxide. H 2 SO 4 (aq) + 2NaOH (aq) → Na 2 SO 4 (aq) + 2HOH (l)

25. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 25 Acid-Base Reactions If however, this same reaction were described in terms of mixing equal numbers of moles, then the coefficients for both reactants would be one (the same number of H and OH must be given away). Example 3: Equal number of moles of sulfuric acid and sodium hydroxide react. H 2 SO 4 (aq) + NaOH (aq) → NaHSO 4 (aq) + HOH (l)

26. Hall © 2005 Prentice Hall © 2005 General Chemistry 4 th edition, Hill, Petrucci, McCreary, Perry Chapter Four 26 Acid-Base Reactions As the following example demonstrates, it is important to take into account the quantity (concentration and amount) of each reactant. Example 4: Equal volumes of 0.1 M phosphoric acid and 0.2 M sodium hydroxide are reacted together. H 3 PO 4 (aq) + 2NaOH (aq) → Na 2 HPO 4 (aq) + 2HOH (l)