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Warm Up: Write in your notes

Warm Up: Write in your notes. What do you already know about chemical and physical changes? What do you already know chemical reactions?. Chapter 9: Chemical Reactions. Writing word and skeletal equations. Chemical Reactions:.

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Warm Up: Write in your notes

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  1. Warm Up: Write in your notes • What do you already know about chemical and physical changes? • What do you already know chemical reactions?

  2. Chapter 9: Chemical Reactions Writing word and skeletal equations

  3. Chemical Reactions: • When the atoms of one or more substances are rearranged to form different substances. CH4 + 2O2 ⇒ CO2 + 2H2O Reactants: Starting substances Products: Ending Substances

  4. Chemical Reaction Symbols: +  Separates two or more reactants or products ⇒  Separates reactants from products ↔  Separates reactants from products and indicates a reversible reaction (s)  Identifies a solid state (l)  Identifies a liquid state (g)  Identifies a gaseous state (aq)  Identifies a water solution (Aqueous)

  5. Law of the Conservation of Mass Mass is neither created nor destroyed during a chemical reaction

  6. Signs of a chemical change: • Energy change • Color change • Odor change • Production of gas • Formation of a solid (precipitate)

  7. Energy Change • Energy either being gained or released as heat or light • Two types: • Exothermic: Energy released by the reaction • We will see light or feel heat • Endothermic: Energy gained by the reaction • We will feel the reaction getting cold

  8. Color Change: • Typically associated with another sign of a chemical change • Mixing of colors, diluting, etc, are not signs of a chemical change

  9. Odor Change: • Rotting, baking, cooking, etc.

  10. Production of Gas • Formation of bubbles, etc • This is not caused by heating or boiling a substance.

  11. Formation of a Solid: • A solid is formed during the reaction, when adding or taking away energy from the rxn. • This solid is known as a precipitate. • It is NOT mean the freezing of a liquid into a solid.

  12. Word Equations: • Chemical Rxn in word format: Solid Aluminum and liquid bromine react to produce solid aluminum bromide.

  13. Skeletal Equations • Chemical reactions using chemical symbols and an arrow. Al(s) + Br2(l) AlBr2(s)

  14. Word and Skeletal Equations: • They are two different ways to write the same thing. Solid Aluminum and liquid bromine react to produce solid aluminum bromide. Al(s) + Br2(l) AlBr2(s)

  15. Key Words: • Reacts: tells us what is reacting with what • We use a + to represent reacts/reacts with • Yields/To form: tells us what the product(s) is • We use an to represent yields/produces/to form * We state the state of the matter for each substance. (solid, liquid, gas, or aqueous

  16. Key Words: • Carbon monoxide gas and oxygen gas react to yield carbon dioxide gas. CO(g) + O2(g) CO2(g)

  17. States of Matter: • Solid (s) • Liquid (l) • Gas (g) • Aqueous (aq) • Use the context clues of the word equation to determine the states of matter of the reactants and products.

  18. Diatomic Elements: • Notice that some of the elements have a 2 after them in their skeletal equations: • These are called diatomics: • These are elements exist in nature as two atoms of the same element together, ONLY when they are not bonded to another element. CO(g) + O2(g) CO2(g) Al(s) + Br2(l) AlBr2(s)

  19. Diatomic Elements: • There are 7 diatomics:

  20. Practice: • Aqueous Sodium hydroxide reacts with aqueous calcium bromide to form aqueous sodium bromide and solid calcium hydroxide.

  21. Practice: • Solid zinc reacts with aqueous sulfuric acid to form hydrogen gas and solid zinc (II) sulfate.

  22. Practice: • Fe(s) + O2(g) Fe203(s)

  23. Practice: • Solid calcium oxide reacts with water to form solid calcium hydroxide.

  24. Practice: • Gaseous sulfur dioxide and oxygen gas react to form sulfur trioxide gas.

  25. Practice: • Solid sodium reacts with chlorine gas to form solid sodium chloride.

  26. Practice: NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)

  27. Ticket out the door: • Please complete your ticket out the door, and turn into me before packing up. • HINT: Make sure you know the 7 diatomic elements tomorrow when you come in the door!

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