1. Chemical Reactions

2. Solutions
Solutions are defined as homogeneous mixtures of two or more pure substances.
The solvent is present in greatest abundance.
All other substances are solutes.
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3. Parts of Solutions Solution- homogeneous mixture.
Solute- what gets dissolved.
Solvent- what does the dissolving.
Soluble- Can be dissolved.
Miscible- liquids dissolve in each other.

4. Aqueous solutions Dissolved in water.
Water is a good solvent because the molecules are polar.
The oxygen atoms have a partial negative charge.
The hydrogen atoms have a partial positive charge.
The angle is 105ºC.

5. Hydration
The process in which an ion is surrounded by water molecules arranged in a specific manner
Ions have charges and are attracted to the opposite charges on the water molecules.

6. How Ionic solids dissolve
Click here for Animation H O H O

7. Dissociation
When an ionic substance dissolves in water, the solvent pulls the individual ions from the crystal and solvates them.
This process is called dissociation.
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8. Dissociation
An electrolyte is a substances that dissociates into ions when dissolved in water.
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9. Electrolytes Electricity is moving charges.
The ions that are dissolved can move.
Solutions of ionic compounds can conduct electricity.
Electrolytes.
Solutions are classified three ways.

10. Types of solutions
Strong electrolytes- completely dissociate (fall apart into ions).
Many ions- Conduct well.
Weak electrolytes- Partially fall apart into ions.
Few ions -Conduct electricity slightly.
Non-electrolytes- Don’t fall apart.
No ions- Don’t conduct.

11. Electrolytes
An electrolyte is a substances that dissociates into ions when dissolved in water.
A nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so.
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12. Electrolytes and Nonelectrolytes
Soluble ionic compounds tend to be electrolytes.
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13. Electrolytes and Nonelectrolytes
Molecular compounds tend to be nonelectrolytes, except for acids and bases.
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14. Electrolytes
A strong electrolyte dissociates completely when dissolved in water.
A weak electrolyte only dissociates partially when dissolved in water.
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15. Strong Electrolytes Are…
Strong acids
Strong bases
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16. Strong Electrolytes Are…
Strong acids
Strong bases
Soluble ionic salts
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17. Acids
Arrhenius defined acids as substances that increase the concentration of H+ when dissolved in water.
Brønsted and Lowry defined them as proton donors.
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18. Acids There are only seven strong acids: Hydrochloric (HCl)
Hydrobromic (HBr)
Hydroiodic (HI)
Nitric (HNO3)
Sulfuric (H2SO4)
Chloric (HClO3)
Perchloric (HClO4)
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19. Bases
Arrhenius defined bases as substances that increase the concentration of OH− when dissolved in water.
Brønsted and Lowry defined them as proton acceptors.
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20. Bases The strong bases are the soluble metal salts of hydroxide ion:
Alkali metals
Calcium
Strontium
Barium
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21. Types of solutions Acids- form H+ ions when dissolved.
Strong acids fall apart completely.
many ions
Memorize this list H2SO4 HNO3 HCl HBr HI HClO3 HClO4
Weak acids- don’ dissociate completely.
Bases - form OH- ions when dissolved.
Strong bases- many ions.
KOH NaOH

22. Solubility
How much of a substance will dissolve in a given amount of water.
Usually g/100 mL
Varies greatly, but if they do dissolve the ions are separated,
and they can move around.
Water can also dissolve non-ionic compounds if they have polar bonds.

23. These things are soluble
Salts with alkali metals and ammonium
Salts of nitrates and chlorates
Salts of sulfates except Ag+, Pb2+, Hg22+, Ba2+,Ca2+ and Sr2+
Salts of chlorides, bromides & iodides except Ag+, Pb2+, and Hg22+

24. Solubility Rules
Most hydroxides are slightly soluble (insoluble) except NaOH and KOH
Sulfides, carbonates, chromates, and phosphates are insoluble
Lower number rules supersede so Na2S is soluble

25. Is it soluble?
LiBr
Ba(NO3)2
CaSO4
PbCl2
CaCO3
K2CO3
Cd(ClO3)2

26. Chemical Reactions

27. All chemical reactions
have two parts
Reactants - the substances you start with
Products- the substances you end up with
The reactants turn into the products.
Reactants ® Products

28. In a chemical reaction The way atoms are joined is changed
Atoms aren’t created or destroyed.
Can be described several ways
In a sentence
Copper reacts with chlorine to form copper (II) chloride.
In a word equation
Copper + chlorine ® copper (II) chloride

29. Symbols used in equations
the arrow separates the reactants from the products
Read “reacts to form”
Yields
The plus sign = “and”
(s) after the formula -solid
(g) after the formula -gas
(l) after the formula -liquid

30. Symbols used in equations
(aq) after the formula - dissolved in water, an aqueous solution.
­ used after a product indicates a gas (same as (g)) (products only)
¯ used after a product indicates a solid (same as (s)) (products only)

31. Symbols used in equations
indicates a reversible reaction (More later)
shows that heat is supplied to the reaction
is used to indicate a catalyst used in this case, platinum.

32. What is a catalyst?
A substance that speeds up a reaction without being changed by the reaction.
A catalyst lowers the activation energy
Activation Energy- minimum amount of energy required by reacting particles in order to form the activated complex and lead to a reaction

33. Skeleton Equation Uses formulas and symbols to describe a reaction
doesn’t indicate how many.
All chemical equations are sentences that describe reactions.

34. Convert these to equations
Solid iron (III) sulfide reacts with gaseous hydrogen chloride to form solid iron (II) chloride and hydrogen sulfide gas.
Nitric acid dissolved in water reacts with solid sodium carbonate to form liquid water and carbon dioxide gas and sodium nitrate dissolved in water.

35. The other way Fe(g) + O2(g) ® Fe2O3(s)
Cu(s) + AgNO3(aq) ® Ag(s) + Cu(NO3)2(aq)

36. Balancing Chemical Equations

37. Balanced Equation Atoms can’t be created or destroyed
All the atoms we start with we must end up with
A balanced equation has the same number of atoms of each element on both sides of the equation.

38. ® O + C O C O O C + O2 ® CO2 This equation is already balanced
What if it isn’t already?

39. ® C C O O C O C + C + O2 ® CO We need one more oxygen in the products.
Can’t change the formula, because it describes what actually happens

40. ® C C O C O C O + O Must be used to make another CO
But where did the other C come from?
Must have started with two C
2 C + O2 ® 2 CO

41. Rules for balancing
Write the correct formulas for all the reactants and products
Count the number of atoms of each type appearing on both sides
Balance the elements one at a time by adding coefficients (the numbers in front)
Check to make sure it is balanced.

42. Never Change a subscript to balance an equation.
If you change the formula you are describing a different reaction.
H2O is a different compound than H2O2
Never put a coefficient in the middle of a formula
2 NaCl is okay, Na2Cl is not.

43. Example R P H O 2 1 4 4 2 2 H2 + H2O O2 ® 2 H2 + H2O O2 ®
The equation is balanced, has the same
number of each kind of atom on both sides
Recount
Changes the O
Make a table to keep track of where you
are at
Need twice as much O in the product
Also changes the H
Need twice as much H in the reactant

44. Example R P 4 2 H 2 4 2 O 1 2 This is the answer 2 H2 + O2 ® 2 H2O
Not this 2 O 1 2

45. Examples CH4 + O2 ® CO2 + H2O AgNO3 + Cu ® Cu(NO3)2 + Ag
Al + N2 ® Al2N3
P + O2 ® P4O10
Na + H2O ® H2 + NaOH

46. Techniques
If an atom appears more than once on a side, balance it last.
If you fix everything except one element, and it is even on one side and odd on the other, double the first number, then move on from there.
C4H10 + O2  CO2 + H2O

47. Predicting the Products
Types of Reactions
Predicting the Products

48. Types of Reactions There are too many reactions to remember
Fall into categories.
We will learn 5 types.
Will be able to predict the products.
For some we will be able to predict whether they will happen at all.
Must recognize them by the reactants

49. #1 Combination Reactions
Combine - put together
2 elements, or compounds combine to make 1 compound.
Ca +O2 ® CaO
SO3 + H2O ® H2SO4
We can predict the products if they are two elements.
Mg + N2 ®

50. Write and balance
Ca(s) + Cl2(g) ®
Fe(s) + O2(g) ®
Al(s) + O2(g) ®

51. Combining two compounds
If they tell you it is combination, you will make one product
Two compounds will make a polyatomic ion.
CO H2O →
H2O + Cl2O7→

52. #2 Decomposition Reactions
decompose = fall apart
one reactant falls apart into two or more elements or compounds.
NaCl Na + Cl2
CaCO CaO + CO2

53. #2 Decomposition Reactions
Can predict the products if it is a binary compound
Made up of only two elements
Falls apart into its elements
H2O

54. #2 Decomposition Reactions
HgO

55. #2 Decomposition Reactions
If the compound has more than two elements you must be given one of the products
The other product will be from the missing pieces
NiCO NiO +
H2CO3(aq)® CO2 +

56. Single Replacement

57. #3 Single Replacement One element replaces another
Reactants must be an element and a compound.
Products will be a different element and a different compound.
Na + KCl ® K + NaCl
F2 + LiCl ® LiF + Cl2

58. Na + KCl ® K + NaCl Cl K Na

59. F2 + 2 LiCl ® 2 LiF + Cl2 Cl Li Li F F Cl Li Li

60. #3 Single Replacement Metals replace metals (and hydrogen)
Al + CuSO4 ®
Zn + H2SO4 ®
Think of water as HOH
Metals replace one of the H, combine with hydroxide.
Na + HOH ®

61. #3 Single Replacement We can tell whether a reaction will happen
Some are more active than other
More active replaces less active
The complete list has been given to you.

62. #3 Single Replacement Higher on the list replaces lower.
If the element by itself is higher, it happens,
if element by itself is lower, it doesn’t

63. #3 Single Replacement Note the *
H can be replaced in acids by everything higher
Only the first 4 (Li - Na) react with water.

64. #3 Single Replacement
Al + HCl ®
Fe + CuSO4 ®
Pb + KCl ®
Al + H2O ®

65. #3 Single Replacement Nonmetals can replace other nonmetals
Limited to F2 , Cl2 , Br2 , I2
The order of activity is that on the table.
Higher replaces lower.
F2 + HCl ®
Br2 + KCl ®

66. Displacement Reactions
In displacement reactions, ions oxidize an element.
The ions, then, are reduced.
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67. Displacement Reactions
In this reaction,
silver ions oxidize
copper metal.
Cu (s) + 2 Ag+ (aq)  Cu2+ (aq) + 2 Ag (s)
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68. Displacement Reactions
The reverse reaction,
however, does not
occur.
Cu2+ (aq) + 2 Ag (s)  Cu (s) + 2 Ag+ (aq) x
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69. #4 Double Replacement Two things replace each other.
Reactants must be two ionic compounds or acids.
Usually in aqueous solution
NaOH + FeCl3 ®
The positive ions change place.
NaOH + FeCl3 ® Fe3+OH- + Na+Cl-
NaOH + FeCl3 ® Fe(OH)3 + NaCl

70. 3NaOH + FeCl3 ® Fe(OH)3 + 3NaCl

71. #4 Double Replacement Will only happen if one of the products
doesn’t dissolve in water and forms a solid
or is a gas that bubbles out.
or is a covalent compound usually water.
Polyatomic ions don’t change from side to side

72. Complete and balance assume all of the reactions take place.
CaCl2(aq) + NaOH(aq) ®
CuCl2(aq) + K2S(aq) ®
KOH(aq) + Fe(NO3)3(aq) ®
H3PO4(aq) + Ca(OH)2(aq) ®

73. How to recognize which type
Look at the reactants
E for element
C for compound
E + E Combination
C Decomposition
E + C Single replacement
C + C Double replacement

74. Types of Reactions Precipitation reactions
When aqueous solutions of ionic compounds are poured together a solid forms.
A solid that forms from mixed solutions is a precipitate
If you’re not a part of the solution, your part of the precipitate

75. Precipitation Reactions
When one mixes ions that form compounds that are insoluble (as could be predicted by the solubility guidelines), a precipitate is formed.
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76. Precipitation reaction
We can predict the products
Can only be certain by experimenting
The anion and cation switch partners
AgNO3(aq) + KCl(aq) ®
Zn(NO3)2(aq) + BaCr2O7(aq) ®
CdCl2(aq) + Na2S(aq) ®

77. Precipitations Reactions
Only happen if one of the products is insoluble
Otherwise all the ions stay in solution- nothing has happened.
Need to use solubility rules to determine if reaction takes place.

78. Ionic Compounds and acids
Fall apart into ions when they dissolve
That’s why they conduct electricity when dissolved.
So when we write them as (aq) they are really separated
NaCl(aq) is really Na+(aq) and Cl-(aq)
K2SO4 (aq) is really K+(aq) and SO42-(aq)

79. Reactions in aqueous solutions
Many reactions happen in solution
Makes it so the ions separate so they can interact.
Solids, liquids, and gases are not separated, only aqueous

80. Writing Net Ionic Equations
Write a balanced molecular equation.
Dissociate all strong electrolytes.
Cross out anything that remains unchanged from the left side to the right side of the equation.
Write the net ionic equation with the species that remain.
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81. Net ionic equations
Written for single and double replacement.

82. AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)
Molecular Equation
The molecular equation lists the reactants and products in their molecular form.
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)
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83. Ionic Equation
In the ionic equation all strong electrolytes (strong acids, strong bases, and soluble ionic salts) are dissociated into their ions.
This more accurately reflects the species that are found in the reaction mixture.
Ag+ (aq) + NO3- (aq) + K+ (aq) + Cl- (aq) 
AgCl (s) + K+ (aq) + NO3- (aq)
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84. Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq)  AgCl (s) + K+(aq) + NO3-(aq)
Net Ionic Equation
To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.
The only things left in the equation are those things that change (i.e., react) during the course of the reaction.
Those things that didn’t change (and were deleted from the net ionic equation) are called spectator ions.
Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq) 
AgCl (s) + K+(aq) + NO3-(aq)
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85. Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq)  AgCl (s) + K+(aq) + NO3-(aq)
Net Ionic Equation
To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.
Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq) 
AgCl (s) + K+(aq) + NO3-(aq)
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86. Ag+(aq) + Cl-(aq)  AgCl (s)
Net Ionic Equation
To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.
The only things left in the equation are those things that change (i.e., react) during the course of the reaction.
Ag+(aq) + Cl-(aq)  AgCl (s)
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87. Write the Equation MgSO4(aq) + NaOH(aq) → H2SO4(aq) + KOH(aq) →
K3PO4(aq) + FeF3(aq) →

88. Last Type
Combustion
A compound composed of only C H and maybe O is reacted with oxygen
If the combustion is complete, the products will be CO2 and H2O.
If the combustion is incomplete, the products will be CO and H2O.
or just C and H2O.
O2 will always be the second reactant

89. Examples Complete combustion of C4H10 Incomplete combustion of C4H10
Complete combustion of C6H12O6
Incomplete combustion of C2H6O

90. Acid-Base Reactions
In an acid-base reaction, the acid donates a proton (H+) to the base.
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91. Neutralization Reactions
Generally, when solutions of an acid and a base are combined, the products are a salt and water.
CH3COOH (aq) + NaOH (aq) CH3COONa (aq) + H2O (l)
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92. Neutralization Reactions
When a strong acid reacts with a strong base, the net ionic equation is…
HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l)
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93. Neutralization Reactions
When a strong acid reacts with a strong base, the net ionic equation is…
HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l)
H+ (aq) + Cl- (aq) + Na+ (aq) + OH-(aq) 
Na+ (aq) + Cl- (aq) + H2O (l)
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94. Neutralization Reactions
When a strong acid reacts with a strong base, the net ionic equation is…
HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l)
H+ (aq) + Cl- (aq) + Na+ (aq) + OH-(aq) 
Na+ (aq) + Cl- (aq) + H2O (l)
H+ (aq) + OH- (aq)  H2O (l)
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95. Gas-Forming Reactions
Some metathesis reactions do not give the product expected.
In this reaction, the expected product (H2CO3) decomposes to give a gaseous product (CO2).
CaCO3 (s) + HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (l)
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96. Gas-Forming Reactions
When a carbonate or bicarbonate reacts with an acid, the products are a salt, carbon dioxide, and water.
CaCO3 (s) + HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (l)
NaHCO3 (aq) + HBr (aq) NaBr (aq) + CO2 (g) + H2O (l)
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97. Gas-Forming Reactions
Similarly, when a sulfite reacts with an acid, the products are a salt, sulfur dioxide, and water.
SrSO3 (s) + 2 HI (aq) SrI2 (aq) + SO2 (g) + H2O (l)
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98. Gas-Forming Reactions
This reaction gives the predicted product, but you had better carry it out in the hood, or you will be very unpopular!
But just as in the previous examples, a gas is formed as a product of this reaction.
Na2S (aq) + H2SO4 (aq)  Na2SO4 (aq) + H2S (g)
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99. Write the complete ionic equation for
FeBr3(aq) + KOH(aq) → KBr (aq) + Fe(OH)3(s)
Fe3+(aq)
Br-(aq)
K+(aq)
OH-(aq)
K+(aq)
Br-(aq)
Fe(OH)3(s) + + + → + +

100. The complete ionic equation is
Fe3+(aq)+ Br-(aq) + K+(aq) +OH-(aq) → K+(aq) +Br-(aq) + Fe(OH)3(s)
K+ and Br- don’t change.
They are spectator ions
Could be eliminated
Fe3+(aq) +OH-(aq) →Fe(OH)3(s)
This is what really changes

101. Net ionic equation
Shows only those particles that change before and after.
Eliminate spectator ions
Needs to be balanced in terms of both mass and charge
Fe3+(aq) +OH-(aq) →Fe(OH)3(s)
Fe3+(aq) +3 OH-(aq) →Fe(OH)3(s)

102. Write the net ionic equation
HCl (aq) + Ba(OH)2 (aq) →
K2CO3(aq) + MgI2(aq) →
CaCl2(aq) + MgSO4(aq) →
Ba(OH)2(aq) + H2SO4(aq) →

103. Write the net ionic equation
Al(s) + FeSO4(aq) →
Cl2(s) + NaI(aq) →

104. Predicting precipitates
Solids formed from aqueous solution.
You can predict them if you know some general rules for solubility.

105. Is there a reaction?
For double replacement- has to make gas, solid or water.
Water from an acid- H+ and a hydroxide- OH- makes HOH
Solids- from solubility rules
Exchange ions and see if something is insoluble