3. a. atoms are not created or destroyed in chemical reactions. (Atomic theory – Unit 3) b. The conservation of atoms: = # and type of atoms on the left side of the arrow (reactants) # and type of atoms on the right side of the arrow (products)

4. c. The conservation of mass  in a chemical reaction, = Mass on the left side of the arrow (mass of the reactants) Mass on the right side of the arrow (mass of the products)

5. a. Never change the subscripts on a given chemical formula. b. Never add more substances than is given in the equation. c. Multiplying the coefficient and the subscripts will give you the number of atoms for that element.

6. 1. 2H 2 O 2. 3C 6 H 12 O 6 3. 4HC 2 H 3 o 2 4. 5C 4 H 10 5. 8NH 4 OH 6. 4(NH 4 ) 2 CO 3

7. a. Check and see which atoms are not balanced. Count the number of atoms for each element on both sides of the arrow and compare. Ex: H 2 O + CO 2  C 6 H 12 O 6 + O 2 # in reactantsElement# in products 2H12 3O8 1C6

8. b. If equation is not balanced, start by giving the most complex/largest compound the coefficient of “1”. Ex : __ H 2 O + __ CO 2  _1_ C 6 H 12 O 6 + __ O 2

9. c. Next, find the atom that only appears once in a compound form on both sides of the arrow which are hydrogen and carbon. Balance that atom by putting the lowest whole number coefficient in front of the whole compound so that the coefficient times the subscript will give the same number of atoms on both sides of the arrow.

10.  Ex: __ H 2 O + __ CO 2  __ C 6 H 12 O 6 + __ O 2 Adjust to be equal to # of products # in reactantsElement# in products 6 x 2 =12 6 is the coefficient of H 2 O 2  12H12 3O8 6 x 1 =6 6 is the coefficient of CO 2 1616C6 Look at the bigger #.

11.  Ex: 6 H 2 O + 6 CO 2  1 C 6 H 12 O 6 + ? O 2 Adjust in reactants # in reactants Element# in products Adjust in products 12H √ 6 O in H 2 O, 12 O in CO 2 6+12=18O8  18=6+12 6 in C 6 H 12 O 6 12 in O 2  6 O 2 6C6√ Find the coefficient d. Repeat until all the elements are balanced.

12. a. Include the state of matter after the compound. (s)  solid, (l)  liquid, (g)  gas, (aq)  aqueous solution b. aqueous solution is a substance is dissolved in water. (homogeneous mixture)

13. c. Balance the atom in the elemental form (i.e., H 2, Cu) last. The reason is that changing the coefficient will not impact any other element. Ex. __Na (s) + __ H 2 O (l)  __ NaOH (aq) + __ H 2 (g) Start with # of oxygen, then hydrogen. Additional Ws1 #5)

14. d. If only a fraction (1/2) will work because of odd number of atoms, then multiple all the coefficients by 2. This will eliminate having fractions in the balanced chemical equation. Ex:__C 3 H 6 (g) + __O 2 (g)  __CO 2 (g) + __H 2 O (g) Additional Ws1 #6)

15. e. If there are polyatomic ions in the equation treat them as a group and balance the group, rather than individual elements. Start with the group that is not balanced or if they are all unbalanced, then choose the most complex or odd number one. Ex:___Ca(NO 3 ) 2 (aq)+ ___Na 3 PO 4 (aq)  __Ca 3 (PO 4 ) 2 (s)+ __NaNO 3 (aq)

16. Ex. ___Ca(NO 3 ) 2 (aq)+ ___Na 3 PO 4 (aq)  __Ca 3 (PO 4 ) 2 (s)+ __NaNO 3 (aq) Adjust to be equal to # in products # in reactantsElement# in products 3 x 1 =3 3 is the coefficient of Ca(NO 3 ) 2 1  3 Ca3 3Na1 3 is the coefficient of Ca(NO 3 ) 2 3 x 2 = 6 2626NO 3 1  6 (equal to reactant) 1PO 4 2 Additional Ws1 #7)-9)

18. a. Definition: two or more small reactants combine to form 1 larger product Ex:__ Na (s) + __ Cl 2 (g)  __ NaCl (s) __ N 2 (g)+ __ H 2 (g)  __ NH 3 ­ (g) E+E  C

19. b. Predicting products i. Metallic Element + Nonmetallic Element  Ionic compound ii. Determine the formula of product. (remember we studied forming formula) iii. Covalent compound  The formula will be given. ME+NME  IC

20. b. Predicting products i. Once the formula of the product is correctly written, then balance the chemical equation using lowest number coefficients Ex:__ Mg (s) + __N 2 (g)  ____ Mg 2+ + N 3-  Mg 3 N 2 __ Na(s) + __ O 2 (g)  ____ ME+NME  IC Transition metal: Most transition metals become +2 charged ion.

21. a. Definition: 1 large reactant breaks down into two or more smaller products; the opposite of combination reactions Ex: ___Na 2 O(s)  __Na (s) + __O 2 (g) ___NH 3 (g)  __N 2 (g) +__H 2 (g) ___Na 2 CO 3 (s)  __Na 2 O(s) +__CO 2 (g)

22. b. Predicting products: i. Simple Binary Compounds  Element +Element Metallic elements are written as single atoms and some nonmetallic elements are written as diatomic molecules. Ex:__ MgO(s)  __ H 2 O(l)  C  ME+(NME) 2

23. a. Hydrocarbons  contain only carbon and hydrogen. b. Carbohydrates  contain only carbon, hydrogen and oxygen. C n H n +O 2  CO 2 +H 2 O

24. c. Definition:Compounds of hydrocarbons and carbohydrates burn completely in oxygen gas to form water and carbon oxides. Ex. Balance the equation. __ CH 4 (g) + __ O 2 (g)  ___ CO 2 (g)+ ___ H 2 O(g) __ C 6 H 12 O 6 (s) + __ O 2 (g)  __ CO 2 (g)+ __H 2 O(g) If there is not enough oxygen, CO gas is produced.

25. d. In the presence of large quantities of oxygen, carbon dioxide and water are formed Ex:___ C 8 H 18 (l) + ___ O 2 (excess)  ___ C 3 H 7 OH(l) + __ O 2 (excess)  After combustion, CO 2 and H 2 O will be produced.

26. a. Definition: A more reactive metallic element loses electrons and becomes positively charged and displaces the less active metallic ion. The less active metallic ion gains electrons and leaves as an element. b. Ex. __ Cu + __ AgNO 3  __ Ag + __Cu(NO 3 ) 2 Cu > Ag  Cu(s) becomes Cu 2+, Ag + becomes Ag (s)

27. c. A more reactive nonmetallic element gains electrons and becomes negatively charged and displaces the less active nonmetallic ion. The less active nonmetallic ion loses electrons and leaves as an element. d. Ex. __ Cl 2 + __ KI  __ I 2 + __KCl Cl 2 > I 2  Cl 2 (g) becomes Cl -, I - becomes I 2 (s)

28. (Least reactive )Au < Pt < Ag < Hg < Cu < Bi < Sb < H 2 < Pb < Sn < Ni < Co < Cd < Fe < Cr < Zn < Mn < Al < Mg < Na < Ca < Sr < Ba < K < Rb < Li (most reactive)

29. (Least reactive ) I 2 < Br 2 < Cl 2 < F 2 (most reactive)

30. e. Predicting Products: i. more reactive metallic element + Ionic compound  less reactive metallic element + Ionic compound Ex:__ Al + __ Cu(NO 3 ) 2 

31. e. Predicting Products: ii. more reactive nonmetallic element + Ionic compound  less reactive nonmetallic element + Ionic compound Ex: __ Cl 2 + __ KBr 

32. More examples: __ Ag + __HCl  __ Cu + __ MgCl 2 

33. e. Definition: Two aqueous (soluble) ionic compounds switch partners in solution, producing one or more precipitates (insoluble solid). See solubility rules below. __ AgNO 3 (aq) + __ KI (aq)  __ AgI (s) + __ KNO 3 (aq) __ Ca(C 2 H 3 O 2 ) 2 (aq) + __ Na 2 CO 3 (aq)  __ CaCO 3 (s) + __ NaC 2 H 3 O 2 (aq) 9. Double Replacement (DR)

34. a. Predicting products: △ ○(aq) ＋ ▲●(aq)  △ ●(aq) + ▲○(s) i. M 1 NM 1 + M 2 NM 2  M 1 NM 2 + M 2 NM 1 Switch

35. a. Predicting products: ii. one of the products M 1 NM 2 or M 2 NM 1 must be insoluble (see solubility rule next page) for this reaction to occur. Ex:__ Pb(NO 3 ) 2 (aq) + __ NaI (aq)  __ (NH 4 ) 2 S (aq) + __ CuSO 4 (aq) 

36. Compounds containing these ions are soluble in water Important exceptions Ammonium: NH 4 + None Group I ions: Li +, Na +, K +, Rb +, Cs + None Nitrates: NO 3 - None Acetates: C 2 H 3 O 2 - None Halides: Cl -, Br-, I - Salts of Ag +, Hg 2 2+, and Pb 2+ Sulfates: SO 4 2- Salts of Ca 2+, Sr 2+, Ba 2+, Hg 2 2+, Pb 2+

37. Compounds containing these ions are insoluble in water Important exceptions Sulfides: S 2- Group I and NH 4 +, Ca 2+, Sr 2+, and Ba 2+ Carbonates: CO 3 2- Group I and NH 4 + Phosphate: PO 4 3- Group I and NH 4 + Hydroxides: OH - Group I, Ca 2+, Sr 2+, Ba 2+ and NH 4 +

38.  Evidences must be one of the list  One table 6 minutes  Take turn to lead each reaction. Everyone must lead at least one table.  Rotation  Table 1,2,3,4,5,6 (Teacher’s demo)  Table 1,2,3,4,5  after observation, need discard solutions. Wash a test tube, put upside down

39.  Rotation  Table 1,2,3,4,5,6 (Teacher’s demo)  Table 3  one student wears gloves  Within 6 minutes, perform experiment, record observation, discuss about types of reaction

40. Reaction #9 Silver nitrate + copper  AgNO 3 (aq) + Cu (s)  Ag (s) + Cu(NO 3 ) 2 (aq) Type of reaction?

41. Reaction #10 Aluminum + copper (II) nitrate  Al (s) + CuCl 2 (aq)  Cu (s) + AlCl 3 (aq) Type of reaction?