1. Chapter 8 Notes

2. Chemical Equations and Reactions I.Describing chemical reactions A.Chemical equations describe chemical reactions B.Evidence that a chemical reaction has occurred 1.Heat and/or light given off 2.Gas produced 3.Precipitate-an insoluble product formed by the reaction of two solutions 4.Color change

3. C. These elements exist as diatomic molecules and must be written with a subscript of two when not in a compound. H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂ They are referred to as HOFBrINCl elements. D. Coefficients are written in front of symbols and formulas to satisfy the Law of Conservation of Mass (balance the equation).

4. E. Word Equation Iron + Oxygen  Iron (III) Oxide (Reactants) (Products) F. Formula Equation (Not Balanced) Fe + O₂  Fe₂O₃

5. G.Balanced Equations ____ Fe + ____ O₂  ____ Fe₂O₃ ____ ________ + ____ ________  ____ ________ + ____ ________ Iron (III) Calcium Iron (III) Calcium Chloride Hydroxide Hydroxide Chloride

6. H. Other symbols (P. 246 –learn them!!!) may be used in a chemical equation. I.Catalyst – A substance used to change the speed of a reaction, but which is not used up MnO₂ 2 H₂ O 2 -------- > 2H₂O + O₂

7. J. Coefficients indicate relative amounts of reactants and products. 2 H₂ + O₂  2H₂O 2 molecules 1 molecule 2 molecules 2 moles 1 mole 2 moles 2[(1.01)(2)]g + (16.00)(2)g = 2[(1.01)(2)+(16.00)] g 4.04g + 32.00g = 36.04g

8. Types of Chemical Reactions A.Synthesis 1.Two or more substances combine to form one compound. 2.__ ________ + __ ________  __ ________ Aluminum Oxygen 3.__ ________ + __ ________  __ ________ Carbon Dioxide WaterCarbonic Acid 4. __ ________ + __ ________  __ ________ Phosphorus Oxygen Diphosphorus Pentoxide

9. B. Decomposition Reactions 1. A compound breaks down into simpler substances. 2. __ ________  __ ________ + __ ________ Mercury (II) Oxide 3.__ ________  __ ________ + __ _______ Calcium Carbonate Calcium Oxide Carbon Dioxide

10. C. Single Replacement Reactions 1.An Element replaces a similar element in a compound 2.__ _____ + __ _____  __ _____ + __ ______ Magnesium Hydrochloric Acid 3.__ ______ + __ ______  __ ______ + __ ______ Potassium Iodide Chloride