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Chapter #3

Chapter #3. Chemical Composition. Chemical Reactions. A chemical reactions is an abbreviated way to show a physical or chemical change A chemical change alters the physical and chemical properties of a substance Factors that indicate a chemical change Change in color

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Chapter #3

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  1. Chapter #3 Chemical Composition

  2. Chemical Reactions • A chemical reactions is an abbreviated way to show a physical orchemical change • A chemical change alters the physical and chemical properties of a substance • Factors that indicate a chemical change • Change in color • Temperature change • Change in odor • Change in taste (we do not taste chemicals) • Reactions always contain an arrow that separates the reactants from the products Reactants Products

  3. Types of Chemical Reactions • Combination reaction (synthesis) • Elements for reactants • Examples: H2 + O2 H2O N2 + H2 NH3 Al + O2 Al2O3 The Law of Conservation of matter, states matter cannot be created nor destroyed, that means equations must be balanced.

  4. Types of Chemical Reactions Combination reaction Continued Balance the first equation H2 + O2 H2O Note two oxygen atoms on the reactant side and only one on the product side, therefore place a two in front of water

  5. Types of Chemical Reactions Balance the first equation H2 + O22H2O Note two oxygen atoms on the reactant side and only one on the product side, therefore place a two in front of water The two now doubles everything in water, thus 4 hydrogen and 2 oxygen. Now place a 2 in front of hydrogen.

  6. Types of Chemical Reactions Balance the first equation 2H2 + O22H2O Note two oxygen atoms on the reactant side and only one on the product side, therefore place a two in front of water The two now doubles everything in water, thus 4 hydrogen and 2 oxygen. Now place a 2 in front of hydrogen.

  7. Types of Chemical Reactions Now balance the second equation N2 + H2 NH3 Note two nigrogen atoms on the reactant side and only one on the product side. Place a 2 in front of ammonia

  8. Types of Chemical Reactions Now balance the second equation N2 + H22NH3 Note two nitrogen atoms on the reactant side and only one on the product side. Place a 2 in front of ammonia. This makes 2 nitrogen atoms and 6 hydrogen atoms. Now place a 3 in front of hydrogen to balance hydrogen atoms.

  9. Types of Chemical Reactions Now balance the second equation N2 + 3 H22NH3 Note two nitrogen atoms on the reactant side and only one on the product side. Place a 2 in front of ammonia. This makes 2 nitrogen atoms and 6 hydrogen atoms. Now place a 3 in front of hydrogen to balance hydrogen atoms.

  10. Types of Chemical Reactions • Decomposition Reaction • Compounds form simpler compounds or elements. • Examples H2OH2 + O2

  11. Types of Chemical Reactions • Decomposition Reaction • Compounds form simpler compounds or elements. • Examples 2H2OH2 + O2

  12. Types of Chemical Reactions • Decomposition Reaction • Compounds form simpler compounds or elements. • Examples 2H2O2H2 + O2 • Notice decomposition reactions are the opposite of combination reactions

  13. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl How do we predict the products? Trade places with the metal or nonmetal with the metal or nonmetal in the compound

  14. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl How do we predict the products? Trade places with the metal or nonmetal with the metal or nonmetal in the compound

  15. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl ZnCl + H Now make the products stable. Slide with Clyde

  16. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl ZnCl2 + H2 Now make the products stable. Slide with Clyde

  17. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl ZnCl2 + H2 Now make the products stable. Now Balance

  18. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + 2HCl ZnCl2 + H2 Now make the products stable. Now Balance

  19. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Another Example: Cl2 + MgBr2 How do we predict the products? Trade places with the metal or nonmetal with the metal or nonmetal in the compound. In this case we are trading nonmetals

  20. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Another Example: Cl2 + MgBr2 Br+ MgCl How do we predict the products? Trade places with the metal or nonmetal with the metal or nonmetal in the compound. In this case we are trading nonmetals

  21. Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Another Example: Cl2 + MgBr2 Br2 + MgCl2 How do we predict the products? Trade places with the metal or nonmetal with the metal or nonmetal in the compound. In this case we are trading nonmetals

  22. Types of Chemical Reactions Double Replacementreactions contain compounds as reactants. HCl + Ca(OH)2CaCl + HOH Check formulas, and slide with Clyde when necessary

  23. Types of Chemical Reactions Double Replacementreactions contain compounds as reactants. HCl + Ca(OH)2CaCl2 + HOH Check formulas, and slide with Clyde when necessary

  24. Types of Chemical Reactions Double Replacementreactions contain compounds as reactants. 2HCl + Ca(OH)2CaCl2 + 2HOH Check formulas, and slide with Clyde when necessary Now Balance!

  25. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H2 + O2 CH4 + O2 What is the oxide of hydrogen?

  26. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H2 + O2 CH4 + O2 What is the oxide of hydrogen? Water

  27. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H2 + O2 H2O CH4 + O2 What is the oxide of hydrogen? Water And the oxide of carbon?

  28. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H2 + O2 H2O CH4 + O2 CO2 + H2O What is the oxide of hydrogen? Water And the oxide of carbon? Carbon dioxide

  29. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. 2H2 + O22H2O CH4 + O2 CO2 + H2O Now balance

  30. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. 2H2 + O22H2O CH4 + O2 CO2 + 2H2O Now balance

  31. Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. 2H2 + O22H2O CH4 + 2O2 CO2 + 2H2O Now balance

  32. Ionic Solution Formation KCN (S) K+(aq) + CN-(aq) Ionic equation Note: Not all ionic solutes are soluble in water. How can we tell if an ionic solute is soluble in water?

  33. Ionic Solution Formation KCN (S) K+(aq) + CN-(aq) Ionic equation Note: Not all ionic solutes are soluble in water. How can we tell if an ionic solute is soluble in water? The solubility rules gives ionic solubility.

  34. Solubility Rules There are some more specific rules that allows us to better estimate the solubility of ionic compounds. You will be given these if you need them.

  35. Ionic Equations Using the solubility rules write the formula equation, the ionic equation and the net ionic equation when aqueous silver nitrate is combined with aqueous sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Formula Equation

  36. Ionic Equations Using the solubility rules write the formula equation, the ionic equation and the net ionic equation when aqueous silver nitrate is combined with aqueous sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Formula Equation Ag+ (aq) + NO3- (aq) + Na+(aq) + Cl-(aq) AgCl (s) + Na+ (aq) + NO3-(aq) Ionic Equation

  37. Ionic Equations Using the solubility rules write the formula equation, the ionic equation and the net ionic equation when aqueous silver nitrate is combined with aqueous sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Formula Equation Ag+ (aq) + NO3- (aq) + Na+(aq) + Cl-(aq) AgCl (s) + Na+ (aq) + NO3-(aq) Ionic Equation Spectator ions are ions that are identical on the reactants and products side of the equation.

  38. Ionic Equations Using the solubility rules write the formula equation, the ionic equation and the net ionic equation when aqueous silver nitrate is combined with aqueous sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Formula Equation Ag+ (aq) + NO3- (aq) + Na+(aq) + Cl-(aq) AgCl (s) + Na+ (aq) + NO3-(aq) Ionic Equation Spectator ions are ions that are identical on the reactants and products side of the equation. Place a around the spectator ions.

  39. Ionic Equations Using the solubility rules write the formula equation, the ionic equation and the net ionic equation when aqueous silver nitrate is combined with aqueous sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Formula Equation Ag+ (aq) + NO3- (aq) + Na+(aq) + Cl-(aq) AgCl (s) + Na+ (aq) + NO3-(aq) Ionic Equation Spectator ions are ions that are identical on the reactants and products side of the equation. Place a around the spectator ions.

  40. Ionic Equations Using the solubility rules write the formula equation, the ionic equation and the net ionic equation when aqueous silver nitrate is combined with aqueous sodium chloride. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Formula Equation Ag+ (aq) + NO3- (aq) + Na+(aq) + Cl-(aq) AgCl (s) + Na+ (aq) + NO3-(aq) Ionic Equation Spectator ions are ions that are identical on the reactants and products side of the equation. Eliminating the spectator ions produces the netionic equation. Ag+ (aq) + Cl- (aq) AgCl (s) Net ionic equation

  41. Yet Another Ionic Equation Write the formula, ionic and net ionic equations when aqueous sodium chloride combines with aqueous calcium bromide.

  42. Yet Another Ionic Equation NaCl(aq) + CaBr2 CaCl2 + NaBr Now balance Write the formula, ionic and net ionic equations when aqueous sodium chloride combines with aqueous calcium bromide.

  43. Yet Another Ionic Equation 2 NaCl(aq) + CaBr2 CaCl2+ NaBr(aq) 2 Now balance Write the formula, ionic and net ionic equations when aqueous sodium chloride combines with aqueous calcium bromide.

  44. Yet Another Ionic Equation 2 NaCl(aq) + CaBr2 CaCl2(aq)+ NaBr(aq) 2 Now balance Write the formula, ionic and net ionic equations when aqueous sodium chloride combines with aqueous calcium bromide.

  45. Yet Another Ionic Equation 2 NaCl(aq) + CaBr2 CaCl2(aq)+ NaBr(aq) 2 Now balance 2Na+(aq) + 2Cl-(aq) + Ca2+(aq) + 2Br-(aq) Ca2+(aq) + 2Cl-(aq) + 2Na+(aq) +2 Br-(aq) Ionic equation Write the formula, ionic and net ionic equations when aqueous sodium chloride combines with aqueous calcium bromide.

  46. Yet Another Ionic Equation 2 NaCl(aq) + CaBr2 CaCl2(aq)+ NaBr(aq) 2 Now balance 2Na+(aq) + 2Cl-(aq) + Ca2+(aq) + 2Br-(aq) Ca2+(aq) + 2Cl-(aq) + 2Na+(aq) +2 Br-(aq) Ionic equation No net ionic equation No Reaction (NR) Write the formula, ionic and net ionic equations when aqueous sodium chloride combines with aqueous calcium bromide.

  47. Types of Chemical Reactions REDOX reactionswhere the oxidation number changes from reactants to products. Oxidation is when the oxidation number increases, by losing of electrons. Reductionis when the oxidation numberdecreases by gaining electrons. Consider the following equation: H2 + O2 H2O What are the oxidation numbers of hydrogen and oxygen? 0 0

  48. Types of Chemical Reactions REDOX reactionswhere the oxidation number changes from reactants to products. Oxidation is when the oxidation number increases, by losing of electrons. Reductionis when the oxidation numberdecreases by gaining electrons. Consider the following equation: H2 + O2 H2O What are the oxidation numbers of hydrogen and oxygen?

  49. REDOX REACTIONS H2 + O2 H2O How about hydrogen and oxygen in water? 0 0 2(1+) 2- = 0

  50. REDOX REACTIONS H2 + O2 H2O How about hydrogen and oxygen in water? Oxidation is caused by the oxygen molecule, so it is referred to as the oxidizing agent (OA) Reduction is caused by the hydrogen molecule, so it is referred to as the reducing agent (RA) 0 0 2(1+) 2- = 0 reduced oxidized

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