1. Chapter 6 Chapter #6 Chemical Reactions

2. Chapter 6 Chemical Reactions A chemical reactions is an abbreviated way to show a chemical 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 ReactantsProducts

3. Chemical Change Evidence Chapter 6

4. Chemical Change Evidence Chapter 6 What is a clue that a chemical reaction has occurred? a)The color changes. b)A solid forms. c)Bubbles are present. d)A flame is produced.

5. Chemical Change Evidence Chapter 6 What is a clue that a chemical reaction has occurred? “Colorless hydrochloric acid is added to a red solution of cobalt(II) nitrate, turning the solution blue.” a)The color changes. b)A solid forms. c)Bubbles are present. d)A flame is produced.

6. Chemical Change Evidence Chapter 6 What is a clue that a chemical reaction has occurred? “A solid forms when a solution of sodium dichromate is added to a solution of lead nitrate.” a)A gas forms. b)A solid forms. c)Bubbles are present. d)A flame is produced.

7. Chapter 6 Types of Chemical Reactions Combination reaction (synthesis) – Elements for reactants – Examples: H 2 + O 2 H 2 O N 2 + H 2 NH 3 Al + O 2 Al 2 O 3 The Law of Conservation of matter, states matter cannot be created nor destroyed, the means equations must be balanced.

8. Chapter 6 Types of Chemical Reactions Balance the first equation H 2 + O 2 H 2 O Note two oxygen atoms on the reactant side and only one on the product side, therefore place a two in front of water

9. Chapter 6 Types of Chemical Reactions Balance the first equation H 2 + O 2 2H 2 O 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.

10. Chapter 6 Types of Chemical Reactions Balance the first equation 2H 2 + O 2 2H 2 O 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.

11. Chapter 6 Types of Chemical Reactions Now balance the second equation N 2 + H 2 NH 3 Note two nitrogen atoms on the reactant side and only one on the product side. Place a 2 in front of ammonia

12. Chapter 6 Types of Chemical Reactions Now balance the second equation N 2 + H 2 2NH 3 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.

13. Chapter 6 Types of Chemical Reactions Now balance the second equation N 2 + 3 H 2 2NH 3 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.

14. Chapter 6 Types of Chemical Reactions Decomposition Reaction – Compounds form simpler compounds or elements. – Examples H 2 OH 2 + O 2

15. Chapter 6 Types of Chemical Reactions Decomposition Reaction – Compounds form simpler compounds or elements. – Examples 2H 2 OH 2 + O 2

16. Chapter 6 Types of Chemical Reactions Decomposition Reaction – Compounds form simpler compounds or elements. – Examples 2H 2 O2 H 2 + O 2 Notice decomposition reactions are the opposite of combination reactions

17. Chapter 6 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 Single Replacement Reactions

18. Chapter 6 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

19. Chapter 6 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

20. Chapter 6 Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl ZnCl 2 + H 2 Now make the products stable. Slide with Clyde

21. Chapter 6 Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + HCl ZnCl 2 + H 2 Now make the products stable. Slide with Clyde Now Balance

22. Chapter 6 Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Example: Zn + 2HCl ZnCl 2 + H 2 Now make the products stable. Slide with Clyde Now Balance

23. Chapter 6 Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Another Example: Cl 2 + MgBr 2 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

24. Chapter 6 Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Another Example: Cl 2 + MgBr 2 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

25. Chapter 6 Types of Chemical Reactions Single Replacement reactions have an element and a compound for reactants. Another Example: Cl 2 + MgBr 2 Br 2 + MgCl 2 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

26. Chapter 6 Types of Chemical Reactions Double Replacement reactions contain compounds as reactants. HCl + Ca(OH) 2 CaCl + HOH Check formulas, and slide with Clyde when necessary Double Replacement Reactions

27. Chapter 6 Types of Chemical Reactions Double Replacement reactions contain compounds as reactants. HCl + Ca(OH) 2 CaCl 2 + HOH Check formulas, and slide with Clyde when necessary

28. Chapter 6 Types of Chemical Reactions Double Replacement reactions contain compounds as reactants. 2HCl + Ca(OH) 2 CaCl 2 + 2HOH Check formulas, and slide with Clyde when necessary Now Balance!

29. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H 2 + O 2 CH 4 + O 2 What is the oxide of hydrogen?

30. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H 2 + O 2 CH 4 + O 2 What is the oxide of hydrogen? Water

31. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H 2 + O 2 H 2 O CH 4 + O 2 What is the oxide of hydrogen? Water And the oxide of carbon?

32. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. H 2 + O 2 H 2 O CH 4 + O 2 CO 2 + H 2 O What is the oxide of hydrogen? Water And the oxide of carbon? Carbon dioxide

33. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. 2H 2 + O 2 2H 2 O CH 4 + O 2 CO 2 + H 2 O Now balance

34. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. 2H 2 + O 2 2H 2 O CH 4 + O 2 CO 2 + 2H 2 O Now balance

35. Chapter 6 Types of Chemical Reactions Combustion Reactions occur when an element or compound combine with oxygen to produce oxides of each element. 2H 2 + O 2 2H 2 O CH 4 + 2O 2 CO 2 + 2H 2 O Now balance

36. The End