Types of Chemical Reactions

1. Types of Chemical Reactions

2. Types of Chemical Reactions • We will learn 5 types of chemical reactions: • Synthesis reactions • Combustion reactions • Decomposition reactions • Single-Replacement reaction • Double-Replacement Reactions • Reactions that form a precipitate • Reactions that form water • Acid/Base or Neutralization Reactions • Reactions that form a gas • Aqueous Reactions

3. Synthesis Reaction • When 2 or more elements or compounds react to form a single product. • A + B  AB • Example: • Sodium combines with chlorine to create table salt (sodium chloride) • 2Na(s) + Cl2(g)  2NaCl(s)

4. Combustion Reaction • When a hydrocarbon burns in oxygen to produce carbon dioxide, water, and heat. • CxHy + O2 H2O + CO2 • Also known as burning. • Example: • Methane (hydrocarbon found in natural gas) burns in the presence of oxygen • CH4(g) + 2O2(g) CO2(g) + 2H2O(g)

5. Decomposition Reaction • When a single compound breaks down into 2 or more elements or compounds. • AB A + B • Example: • Sodium azide decomposes into sodium and nitrogen gas when an airbag inflates. • 2NaN3(s) 2Na(s) + 3N2(g)

6. 4 Common Decomposition Reactions • Metallic Hydroxides  Metal Oxide + H2O • Ca(OH)2(s)  →    CaO(s)  +  H2O(g) • Metallic Carbonates  Metal Oxide + CO2 • CaCO3(s)  →    CaO(s)  +  CO2(g) • Metallic Chlorates  Metal Chloride + O2 • 2KClO3 (s)   →    2KCl (s)  +  3O2 (g) • Oxyacids  Non-Metallic Oxide + H2O • H2SO4(aq)  →  H2O (l) +  SO3 (g)

7. Single Replacement Reaction • One element replaces another element in a compound. • Can be: • Metal replaces hydrogen • metal replaces metal • Non-metal replaces non-metal • More active elements replace less active elements. • A + BX  AX + B • Example: • When lithium is combined with water, lithium replaces hydrogen to be come lithium hydroxide, and hydrogen gas is released. • 2Li(s) + 2H2O(l)  2LiOH(aq) + H2(g)

8. Double Displacement Reaction • Ions are exchanged between 2 compounds. • 3 general types: • Produces a gas • Produces a precipitate • Produces water (acid/base reaction) • AX + BY  AY + BX • Example: • 2NaOH(aq) + CuCl2(aq)  2NaCl(aq) + Cu(OH)2(s) (-) ions (+) ions precipitate

9. Rules for Determining the Type of Reactions You Have • Does your reaction have oxygen as one of it's reactants and carbon dioxide and water as products? If yes, then it's a combustion reaction • Does your reaction have two (or more) chemicals combining to form one chemical? If yes, then it's a synthesis reaction • Does your reaction have one large molecule falling apart to make several small ones? If yes, then it's a decomposition reaction • Does your reaction have any molecules that contain only one element? If yes, then it's a single displacement reaction • If you haven't answered "yes" to any of the questions above, then you've got a double displacement reaction • Does this double replacement reaction have water as one of the products? If yes, then it's an acid-base reaction • Does this double replacement reaction form a solid? If yes, it forms a precipitate. • Does this double replacement reaction form a gas? If yes, then it forms a gas. Duh.

10. Practice • Determine the reaction type for each of the following equations: • 2Fe + O2 2FeO  • 4Fe + 3O2 2Fe2O3 • 2C4H10 + 13O2 8CO2 + 10H2O • Ca(OH)2 + H3PO4 Ca3(PO4)2 + H2O • 2NaCl  2Na + Cl2 • 2Na + H2O  2NaOH + H2 • N2 + 3H2 2NH3 • HCl + FeS FeCl2 + H2S • Fe + CuSO4 FeSO4 + Cu • 2P + 3Cl2 2PCl3 • HCl + AgNO3 HNO3 + AgCl SYNTHESIS SYNTHESIS COMBUSTION DOUBLE DISPLACEMENT DECOMPOSITION SINGLE REPLACEMENT SYNTHESIS DOUBLE REPLACEMENT SINGLE DISPLACEMENT SYNTHESIS DOUBLE DISPLACEMENT

11. Practice • WS #5 Types of Rxns

12. Predicting Single Replacement Reactions • Single replacement reactions will not occur if the metal or non metal doing the replacing is less reactive. • For example: • 2K + MgCl2 2KCl + Mg (reacts) • Zn + NaCl  NR (no reaction) • A less reactive element WILL NOT replace a mor reactive elements • For nonmetal halogens: • F > Cl > Br > I

13. Practice • WS #6 Single Replacement w/ Activity Series • WS #7 Single Replacement w/ AS

14. Predicting Products in General • For predicting products in general, identify the type of reaction, and then apply the general rule for that reaction. • For example, predict the following: • Ag2SO4 + NaNO3??? • 2 ionic compounds = double replacement • Switch your metals using proper naming rules • Balance your equation • Ag2SO4+ 2NaNO3 2AgNO3 + Na2SO4

15. Practice • Predict the products of the following reaction: • CH4 + O2  ??? • Hydrocarbon + oxygen = combustion • Products are always carbon dioxide + water • Balance your equation • CH4 + 2O2  CO2 + 2H2O

16. Practice • WS #8 Predicting Products • WS #9 Predicting • WS #10 Predicting

19. Reactions in Aqueous Solutions: Special Cases of Double-Replacement Reactions • 3 Special Cases: • Reactions that form precipitates (solids) • Reactions that form water (acid/base or neutralization) • Reactions that form a gas • Solute = what is dissolved • Solvent = what something is dissolved in • Aqueous solution = solvent is water • Some solutes are molecular compounds that remain as molecules in solution. • Other solutes are molecular compounds that form ions in solution. • You must be able to write complete ionic equations and net ionic equations (no spectator ions) for reactions that involve ions in aqueous solutions.

20. Reactions That Form Precipitates • A double-displacement reaction • The molecular compounds form ions in solution • Must write complete & net ionic equations • Example: • Aqueous solutions of sodium hydroxide and copper(II) chloride for sodium chloride and copper(II) hydroxide (the precipitate). • 2NaOH(aq) + CuCl2(aq)  2NaCl(aq) + Cu(OH)2(s)

21. Ionic Equations of Precipitate Reaction • 2NaOH(aq) + CuCl2(aq)  2NaCl(aq) + Cu(OH)2(s) Written showing all ions you get: • 2Na+(aq) + 2OH-(aq) + Cu2+(aq) + 2Cl-(aq)  2Na+(aq) + 2Cl-(aq) + Cu(OH)2(s) However, removing the ions that do not participate (in reactants and products) leaves the net ionic equation: • 2OH-(aq) + Cu2+(aq)  Cu(OH)2(s)

22. Reactions That Form Water • Double-displacement reaction • No evidence of reaction is observable, because reaction creates more solvent. • For example, when you mix hydrobromic acid with sodium hydroxide, sodium bromide and water are formed. • HBr(aq) + NaOH(aq)  H20(l) + NaBr(aq) • The Ionic Equation is: • H+(aq) + Br-(aq) + Na+(aq) + OH-(aq)  H2O(l) + Na+(aq) + Br-(aq) • Net Ionic Equation: • H+(aq) + OH-(aq)  H2O(l)

23. Reactions That Form Gases • Double-displacement reaction • Hydroiodic acid and lithium sulfide react to form hydrogen gas and lithium iodide. • 2HI(aq) + Li2S(aq)  H2S(g) + 2LiI(aq) • Complete ionic equation: • 2H+(aq) + 2I-(aq) + 2Li+(aq) + S2-(aq)  H2S(g) + 2Li+(aq) + 2I-(aq) • Net ionic equation: • 2H+(aq) + S2-(aq)  H2S(g)

24. Another Example • When sodium hydrogen carbonate is dissolved in hydrochloric acid, and gas producing double-displacement reaction occurs simultaneously with a decomposition reaction. • HCl(aq) + NaHCO3(aq)  H2CO3(aq) + NaCl(aq) and H2CO3(aq)  H2O(l) + CO2(g)

25. Combining the 2 Reactions Yields • HCl(aq) + NaHCO3(aq)  H2CO3(aq) + NaCl(aq) • H2CO3(aq)  H2O(l) + CO2(g) +____________________________________ • HCl(aq) + NaHCO3(aq) + H2CO3(aq)  H2CO3(aq) + NaCl(aq) + H2O(l) + CO2(g) • Removing substances on both sides yields: • HCl(aq) + NaHCO3(aq)  NaCl(aq) + H2O(l) + CO2(g)

26. Complete & Net Ionic Equations • H+(aq) + Cl-(aq) + Na+(aq) + HCO3-(aq)  H2O(l) + CO2(g) + Na+(aq) + Cl-(aq) Removing spectator ions: • H+(aq) + Cl-(aq) + Na+(aq) + HCO3-(aq)  H2O(l) + CO2(g) + Na+(aq) + Cl-(aq) So the net ionic equation is: • H+(aq) + HCO3-(aq)  H2O(l) + CO2(g)

27. Practice