1. LecturePLUS Timberlake1 Identifying and Balancing Chemical Reactions Chemical Changes Balancing Chemical Equations

2. LecturePLUS Timberlake2 Physical Properties color melting point boiling point electrical conductivity specific heat density state (solid, liquid, or gas)

3. LecturePLUS Timberlake3 Physical Change Changes in physical properties melting boiling condensation No change occurs in the identity of the substance Example: Ice, rain, and steam are all water

4. LecturePLUS Timberlake4 Chemical Change Atoms in the reactants are rearranged to form one or more different substances Old bonds are broken; new bonds form Examples: Fe and O 2 form rust (Fe 2 O 3 ) Ag and S form tarnish (Ag 2 S)

5. LecturePLUS Timberlake5 Learning Check E1 Classify each of the following as a 1) physical change or 2) chemical change A. ____ a burning candle B. ____ melting ice C. ____ toasting a marshmallow D. ____ cutting a pizza E. ____ polishing silver

6. LecturePLUS Timberlake6 Solution E1 Classify each of the following as a 1) physical change or 2) chemical change A. __2__ a burning candle B. __1_ melting ice C. __2__ toasting a marshmallow D. __1__ cutting a pizza E. __2__ polishing silver

7. LecturePLUS Timberlake7 Chemical Reaction A process in which at least one new substance is produced as a result of chemical change.

8. LecturePLUS Timberlake8 Evidence for A Chemical Reaction Five Signs of a Chemical Change 1.Gas Given Off (Bubbles) 2.Color Change (BIGGIE!!!!!!) 3.Heat is Produced or Absorbed 4.Odor Change 5.Precipitate Forms (Solid is Made)

9. LecturePLUS Timberlake9 Chemical Equations Chemical Equations are used to represent chemical reactions. Reactants  Products Law of Conservation of Matter (Mass) States: “Matter cannot be created or destroyed during a chemical reaction.” We must balance chemical reactions (add coefficients) to comply with the law.

10. LecturePLUS Timberlake10 Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction ReactantsProducts MgO + CCO + Mg magnesium oxide to form carbon monoxide reacts with carbon and magnesium

11. LecturePLUS Timberlake11 Words to watch for States of matter – This is a symbol that is used to identify the state of matter for each substance in a reaction. Gas, Liquid, Solid, Aqueous –Gas (g) –Liquid (l) –Solid (s) may also be called a Precipitant (ppt) or a crystal (c) –Aqueous (aq) means dissolved in water.

12. LecturePLUS Timberlake12 Reading A Chemical Equation 4 NH 3 + 5 O 2 4 NO + 6 H 2 O Four molecules of NH 3 react with five molecules O 2 to produce four molecules NO and six molecules of H 2 O or Four moles NH 3 react with 5 moles O 2 to produce four moles NO and six moles H 2 O

13. LecturePLUS Timberlake13 A Balanced Chemical Equation Same numbers of each type of atom on each side of the equation Al + S Al 2 S 3 Not Balanced 2Al + 3S Al 2 S 3 Balanced

14. LecturePLUS Timberlake14 Five Types of Chemical Reactions 1.Synthesis (Combination) Reaction 2.Decomposition Reaction 3.Single Replacement (Displacement) Reaction 4.Double Replacement (Displacement) Reaction 5.Combustion Reaction

15. LecturePLUS Timberlake15 Synthesis Reaction 1.Two or More Reactants combine to form one reactant. 2.A + B  AB 3.H 2 (g) + Cl 2 (g)  2 HCl (g)

16. LecturePLUS Timberlake16 Decomposition Reaction 1.One Reactant breaks apart to form More Products. 2.AB  A + B 3.2 HCl (g)  H 2 (g) + Cl 2 (g) 4.ABC  A + B + C 5. 2 NaHCO 3 (s)  Na 2 CO 3 (s) + H 2 O(g) + CO 2 (g)

17. LecturePLUS Timberlake17 Single Replacement (Displacement) In a Single Replacement One element replaces another element in a compound. Metals replace Metals and Nonmetals replace Nonmetals. A + BX  B + AX Na(s) + Cu(OH) 2 (aq)  Cu(s) + 2 NaOH(aq) F 2 (g) + 2 KI (aq)  2 KF (aq) + I 2 (s)

18. LecturePLUS Timberlake18 More on Single Replacement Reactions The charges (oxidation numbers) on atoms become changed by the reaction. Some atoms have their charges reduced (go down), some atoms have their charges increased (go up) In the last reaction, Na went from 0 to +1 and Cu went from +2 to 0 Na gave it’s electrons to Cu O and H were not effected.

19. LecturePLUS Timberlake19 Double Replacement (Displacement) In a Double replacement reaction, Metals (Cations) trade Nonmetals (Anions) A solid, gas or water must be a product. NaCl (aq) + AgNO 3 (aq)  NaNO 3 (aq) + AgCl (s) Notice the Nitrate and the Chloride changed places and solid AgCl was formed

20. LecturePLUS Timberlake20 Combustion In a Combustion reaction, something is burned in the presence of Oxygen (O 2 ). Normally the one of the reactants has C and H (Hydrocarbon). CH 4 (g) + O 2 (g)  CO 2 (g) + 2 H 2 O (g) OXYGEN MUST BE A REACTANT. No Oxygen, No Combustion.

21. LecturePLUS Timberlake21 Learning Check – R1 Identify each of the following types of reactions: 2 Na (s) + F 2 (g)  2 NaF (s) 2 C 2 H 6 (g) + 7 O 2 (g)  4 CO 2 (g) + 6 H 2 O (g) CaCO 3 (s)  CaO (s) + CO 2 (g) 2 NaOH (aq) + CuCl 2 (aq)  2 NaCl (aq) + Cu(OH) 2 (s)

22. LecturePLUS Timberlake22 Learning Check – R1 Answers Synthesis (Combination) Combustion Decomposition Double Replacement

23. LecturePLUS Timberlake23 Matter Is Conserved H 2 + Cl 2 2 HCl ++ Total atoms=Total atoms 2 H, 2 Cl2H, 2 Cl Total Mass=Total Mass 2(1.0) + 2(35.5)2(36.5) 73.0 g=73.0 g

24. LecturePLUS Timberlake24 Law of Conservation of Mass In any ordinary chemical reaction, matter is not created nor destroyed

25. LecturePLUS Timberlake25 Balance Equations with Coefficients Coefficients in front of formulas balance each type of atom 4NH 3 + 5O 2  4NO + 6H 2 O 4 N4 12 H12 10O10

26. LecturePLUS Timberlake26 Steps in Balancing An Equation Fe 3 O 4 + H 2 Fe + H 2 O Fe: Fe 3 O 4 + H 2 3 Fe + H 2 O O:Fe 3 O 4 + H 2 3 Fe + 4 H 2 O H: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O

27. LecturePLUS Timberlake27 Learning Check E4 Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 1) 22) 43) 8 B. Number of O atoms in 4 H 2 O 1) 22) 43) 8 C. Number of Fe atoms in Fe 3 O 4 1) 12) 33) 4

28. LecturePLUS Timberlake28 Solution E4 Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 3) 8 B. Number of O atoms in 4 H 2 O 2) 4 C. Number of Fe atoms in Fe 3 O 4 2) 3

29. LecturePLUS Timberlake29 Learning Check E5 Balance each equation. The coefficients for each equation are read from left to right A. Mg + N 2 Mg 3 N 2 1) 1, 3, 2 2) 3, 1, 2 3) 3, 1, 1 B. Al + Cl 2 AlCl 3 1) 3, 3, 22) 1, 3, 13) 2, 3, 2

30. LecturePLUS Timberlake30 Learning Check E5 C. Fe 2 O 3 + C Fe + CO 2 1) 2, 3, 2,3 2) 2, 3, 4, 3 3) 1, 1, 2, 3 D. Al + FeO Fe + Al 2 O 3 1) 2, 3, 3, 1 2) 2, 1, 1, 1 3) 3, 3, 3, 1 E. Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2 1) 3, 2, 1, 2 2) 2, 3, 1, 3 3) 2, 3, 2, 3

31. LecturePLUS Timberlake31 Solution E5 A. 3 Mg +N 2 Mg 3 N 2 B. 2 Al + 3 Cl 2 2 AlCl 3 C. 2 Fe 2 O 3 + 3 C 4 Fe + 3 CO 2 D. 2 Al + 3 FeO 3 Fe + Al 2 O 3 E. 2 Al + 3 H 2 SO 4 Al 2 (SO 4 ) 3 + 3 H 2