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Chemical Equations Chapter 9. 9-1 What is a chemical reaction? We represent chemical change with a chemical reaction. Evidence that a chemical reaction.

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Presentation on theme: "Chemical Equations Chapter 9. 9-1 What is a chemical reaction? We represent chemical change with a chemical reaction. Evidence that a chemical reaction."— Presentation transcript:

1 Chemical Equations Chapter 9

2 9-1 What is a chemical reaction? We represent chemical change with a chemical reaction. Evidence that a chemical reaction has occurred:  Evolution of a gas  Color change  Energy given off or absorbed  Formation of a precipitate

3 9-1 What is a chemical reaction?  Atoms break apart and rearrange themselves to form new substances with new chemical and physical properties. yield REACTANTS  PRODUCTS

4 9-2 How are chemical reactions written?  Word equations copper + oxygen  copper (II) oxide  Formula equations Cu + O 2  CuO  Balancing equations Law of Conservation of Matter – Matter can not be created of destroyed; it only changes form (# of each atom on the reactant side MUST equal # of each atom on the product side.)

5

6 9-3 What does a chemical equation tell you?  Conditions  Physical states

7 9-3 What does a chemical equation tell you?  Quantitative relationships (proportions)

8 9-3 What does a chemical equation tell you?  Energy changes- Chemical equations can also tell you the amount of energy that was absorbed or released during the rearrangement.  This is called change in enthalpy and is represented by Δ H  Exothermic reactions  Energy is released from the system into the surroundings (feels hot).  Endothermic reactions  Energy was absorbed into the system from the surroundings (feels cold). Remember: Energy can be heat or light

9 9-4 Classification of Reactions (Product Prediction) There are 5 types of chemical reactions:  Single Replacement  Double Replacement  Synthesis  Decomposition  Combustion


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