1. Ch10 – Intro to Chemical Reactions Spring 2016

2. Chemical Reactions One or more substances are rearranged to form different substances C 8 H 18 + O 2  CO 2 + H 2 O + ENERGY LOOK, IT’S A HYDROCARBON!!!!! The products are carbon dioxide and water!

3. Indicators of Chemical Reactions Animation of Experiment (GIF Format, 321 k)Animation of Experiment (GIF Format, 321 k) Temperature Change Color Change Odor Production of Gas Bubbles Production of a Precipitate

4. Representing Chemical Reactions SymbolMeaning + Separates two or more reactants or products -> Separates reactants from products (s) Solid state (l) Liquid state (g) Gaseous state (aq) Water solution Statements called equations are used to describe what happens during a chemical reaction Reactants are the starting substances found on the left side of the equation Products are the substances formed during a reaction

5. Types of Reactions 1.Synthesis reactions 2.Decomposition reactions 3.Single displacement reactions 4.Double displacement reactions 5.Combustion reactions You need to be able to identify each type.

6. 1. Synthesis Example C + O 2 OO C +  OO C General: A + B  AB

7. Ex. Synthesis Reaction

8. Practice Predict the products. Na (s) + Cl 2(g)  Mg (s) + F 2(g)  Al (s) + F 2(g)  NaCl (s) MgF 2(s) AlF 3(s) 2 2 232 Now, balance them.

9. 2. Decomposition Example: NaCl General: AB  A + B  Cl Na Cl + Na

10. Ex. Decomposition Reaction

11. 3. Single Displacement Example: Zn + CuCl 2  Zn Cl Cu + General: AB + C  AC + B Cl Zn Cu + Zn was oxidized Went from neutral (0) to (+2) Cu was reduced Went from (+2) to Neutral (0)

12. Ex. Single Replacement Reaction

13. Single Replacement Reactions Write and balance the following single replacement reaction equation: Zn (s) + HCl (aq)  ZnCl 2 + H 2(g) 2 NaCl (s) + F 2(g)  NaF (s) + Cl 2(g) Al (s) + Cu(NO 3 ) 2(aq)  22 Cu (s) + Al(NO 3 ) 3(aq) 3 23 2

14. 4. Double displacement Example: MgO + CaS General:AB + CD  AD + CB S O  Mg Ca + O S Mg Ca +

15. Double Replacement Reactions Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO 3(aq) + NaCl (s)  AgCl (s) + NaNO 3(aq) Another example: K 2 SO 4(aq) + Ba(NO 3 ) 2(aq)  KNO 3(aq) + BaSO 4(s) 2

16. Practice Predict the products. 1.HCl (aq) + AgNO 3(aq)  2.CaCl 2(aq) + Na 3 PO 4(aq)  3.Pb(NO 3 ) 2(aq) + BaCl 2(aq)  4.FeCl 3(aq) + NaOH (aq)  5.H 2 SO 4(aq) + NaOH (aq)  6.KOH (aq) + CuSO 4(aq) 

17. 5. Combustion Reactions Combustion reactions - a hydrocarbon reacts with oxygen gas. This is also called burning!!! In order to burn something you need the 3 things in the “fire triangle”: 1) Fuel (hydrocarbon) 2) Oxygen 3) Something to ignite the reaction (spark)

18. Combustion Reactions In general: C x H y + O 2  CO 2 + H 2 O Products are ALWAYS carbon dioxide and water. (although incomplete burning does cause some by-products like carbon monoxide) Combustion is used to heat homes and run automobiles (octane, as in gasoline, is C 8 H 18 )

19. Combustion Example C 5 H 12 + O 2  CO 2 + H 2 O Write the products and balance the following combustion reaction: C 10 H 22 + O 2  5 6 8

20. Mixed Practice State the type & predict the products. 1.BaCl 2 + H 2 SO 4  2.C 6 H 12 + O 2  3.Zn + CuSO 4  4.Cs + Br 2  5.FeCO 3 

21. Word Equations and Skeleton Equations Word Equations -Statements that indicate the reactants and products in a rxn -Describe chemical reactions -Lack important information Iron (s) + chlorine (g) -> iron (III) chloride (s) Skeleton Equations -Uses chemical formulas to identify reactants and products Fe (s) + Cl 2 (g) -> FeCl 3 (s)

22. Practice Problems Write skeleton equations for the following word equations: 1. hydrogen (g) + bromine (g) -> hydrogen bromide (g) H 2 (g) + Br 2 (g) -> HBr (g) 2. carbon monoxide (g) + oxygen (g) -> carbon dioxide (g) CO (g) + O 2 (g) -> CO 2 (g) 3. potassium chlorate (s) -> potassium chloride (s) + oxygen (g) KClO 3 (l) -> KCl (s) + O 2 (g)