Chemical Reactions

1. Chemical Reactions

2. Chemical Reactions • Chemical Reaction: process by which atoms of one or more substances are rearranged to form different substances • Process of chemical change • Breaking old bonds and forming new ones

3. Evidence of Chemical Reactions • Change in temperature • Change in color • Change in odor • Production of a gas • Formation of a solid (precipitate)

4. Representing Chemical Reactions • Use formulas and symbols • Reactants on left; products on right • Chemical equations • Correct form • Balanced • For AP Chemistry • Soluble ions shown when aqueous. • Balanced Net Ionic Equations

5. Balancing Equations • Use coefficients to balance • Ions and other species that are the same form in reactants and products cancel out—are omitted. • Steps • Skeleton equation • Check numbers of atoms of products and reactants • Insert coefficients to balance (use smallest whole number ratio of coefficients) • Check to see if ions are in solution on reactants and products and cancel if needed. • Hints: metals, nonmetals, polyatomic ions that stay together, diatomic molecules

6. 6 Main Types of Reactions • Synthesis (putting together) • Combustion (combining with oxygen) • Decomposition (breaking down) • Single Displacement (one element replaces another from a compound) • Double Displacement (two similar elements switch places) • Ligand formation • Basic organic reactions

7. 1. Synthesis Reactions • A + B  AB • In general, two or more substances combine to give one new substance • At least one of the products has to be more complex than either of the reactants

8. Types of Synthesis Reactions • Metal + Oxygen  Metal oxidesecond video • Nonmetal + Oxygen  Nonmetal oxide • Metal + Nonmetal  Salt • Metal oxide + Water  Metal hydroxide • Nonmetal oxide + Water  Oxyacid

10. Annual Mean Wet Sulfate Deposition 1989 through 1991 (top) and 2001 through 2003 (bottom) Image: EPA

11. QuarryExtraction of Calcium Carbonate by Blasting, Crushing and Screening. • KilnCalcination occurs in a Maerz shaft kiln at 1000oCproducing Calcium Oxide.

12. HydratorCalcium oxide is mixed with water in a controlled process to produce either aqueous Calcium Hydroxide or dry Calcium Hydroxide powder. Packaging PlantCalcium Hydroxide ispackaged into 25kg Bags in an automated plant.

13. 2. Combustion Reactions • Oxygen combines with a substance and releases energy in the form of heat and light • Burning! • Combustion reactions can also be classified as synthesis or decomposition in some cases

14. 3. Decomposition Reactions • AB  A + B • Breaking down of a substance into two or more simpler substances • The products have to be simpler than any of the reactants

15. Types of Decomposition Reactions • Metal oxide  Metal + Oxygen • Metal carbonate  Metal oxide + carbon dioxide • Metal hydrogen carbonate  Metal carbonate + Water + Carbon dioxide • Metal chlorate  Metal chloride + oxygen • Metal nitrates  Metal nitrites + oxygen • Hydrogen peroxide  Water + oxygen

16. 4. Single Displacement Reactions • A + BX  AX + B • A SINGLE element replaces a similar element that is part of a compound • Only happens if the single (free) element is MORE ACTIVE than the similar element in the compound • Use Activity Series to predict whether or not Single Displacement Reactions will occur • Watch net ionic equation form

17. Types of Single Displacement Reactions • Metal (active) + Acid  Hydrogen + Salt • Metal (active) + Water  Hydrogen + Metal hydroxide • Metal + Salt  Metal + Salt • Halogen + Halide salt  Halogen + Halide salt *CONSULT ACTIVITY SERIES

18. 5. Double Displacement Reactions • AX + BY  AY + BX • Similar elements in two different compounds “switch” places • One of the products MUST be either water, a gas, or a solid (insoluble) precipitate • Use solubility rules • Watch net ionic equation form

19. Types of Double Displacement Reactions • Written as chemical, ionic and net ionic equations • MUST produce either water, a gas, or a precipitate • Use Solubility Table and Solubility Rules to predict reaction

20. Complex Ions • The Lewis base that forms complex ions are called LIGANDs—some examples are • CN • NH3 • Br • Cl Some common Ligands

21. Complex Ions • Transition metals often combine with a Lewis base to form a complex ion • Compounds made from complex ions are called coordination compounds CN NH3 Br Cl [Ni(NH3)6] Cl2 K3[Fe(CN)6] counter ions metal complex2+ cation metal complex3- anion

22. Coordination Compounds A coordination compound consists of a complex ion and counter ions. – it is an ionic compound, electrically neutral. – complex ion = transition metal ion + attached ligands. E.g. [Co(NH3)5Cl]Cl2 Co(NH3)5Cl2+ ← complex ion 2 Cl- ← counter ions (anions)

23. Coordination Compounds • Coordination Number of Metal Ions • – The number of bonds formed between a metal ion and the ligands in the complex ion is termed the coordination number. • The coordination number is (OFTEN) twice the charge of the metal ion.

24. the metal ion is a Lewis acid • a metal – ligand bond is called a coordinative covalent bond. • it results from a Lewis acid – base interaction in which a ligand donates an electron pair to an empty orbital on a metal ion.

25. 6. Ligand reactions in AP chemistry Writing the reactions that form the coordination ions requires (1) recognition of the possibility of the formation of the coordination ion when an ample source of the ligands is available (2) knowledge of the metal ions likely to form coordination ions, of what the common ligands are, and of the likely number of the ligands to be attached to the central ion. It may be useful to keep in mind that the number of ligands attached to a central metal ion is sometimes twice the oxidation number of the central metal: Ag + + 2 NH3 Ag(NH3)2+ Zn 2+ + 4 OH- Zn(OH)4-2

26. 6. Ligand reactions in AP chemistry Writing the reactions that form the coordination ions requires • The breakup of these coordination ions is frequently achieved by adding an acid. The products are the metal ion and the species formed when hydrogen ions from the acid react with the ligand Ag(NH3)2+  Ag + + 2 NH3 Zn(OH)4-2 Zn 2+ + 4 OH -

27. Organic Reactions in AP chemistry • Predicting the products of the limited number of organic reactions appropriate for the Advanced Placement Chemistry • The more common types of reactions include the following

28. Organic reactions 7. Oxidation Complete oxidation of any organic compound containing no elements but carbon, hydrogen, and oxygen yields carbon dioxide and water.

29. Organic reactions 8. Addition These reactions, which form only one product, are the characteristic reactions of the hydrocarbon series whose members have double or triple bonds.

30. Organic reactions 9. Substitution These reactions give two products. Any hydrocarbon can show this type of reaction. It is the characteristic reaction for the hydrocarbon series that have no multiple bonds. A hydrogen atom leaves the organic compound and is bonded to an atom or atoms from the nonorganic reactant. The place of the hydrogen in the organic compound is taken by an atom or radical from the nonorganic reactant.

31. Organic reactions 10. EtherificationAn organic acid reacts with an alcohol to form an ester and water.

32. Organic reactions 11. Saponification. An ester reacts with a strong base to form a salt, which may be a soap, and an alcohol.