1. Chemical Reactions Chapter 3 3.7-3.10

2. 3.7 Acid and Base Reactions  Acids and Bases acids produce carbon dioxide when added to a metal carbonate acids produce carbon dioxide when added to a metal carbonate acids often react with metals to produce H 2 acids often react with metals to produce H 2 acids taste sour/bases taste bitter acids taste sour/bases taste bitter strong acids/bases completely ionize in water strong acids/bases completely ionize in water weak acids/bases partially ionize weak acids/bases partially ionize

3. Acids and Bases: Arrhenius Definition  An acid is a substance that, when dissolved in water, increases the concentration of hydrogen ions, H + (aq), in the water.

4. Acids and Bases: Arrhenius Definition  A base is a substance that, when dissolved in water increases the concentration of hydroxide ion, OH -, in the water.  ammonia produces hydroxide in water, forming ammonium and hydroxide ion  common acids and bases on page 132

5. Acid and Base Reactions  Strong Acids HCl, HBr, HI, H 2 SO 4, HNO 3, HClO 4 HCl, HBr, HI, H 2 SO 4, HNO 3, HClO 4  Strong Bases Group 1 Hydroxides Group 1 Hydroxides LiOH, NaOH…LiOH, NaOH… Group 2 Hydroxides Group 2 Hydroxides Ca(OH) 2, Sr(OH) 2, Ba(OH) 2Ca(OH) 2, Sr(OH) 2, Ba(OH) 2

6. Reactions of Acids and Bases  acids react with strong bases to produce a salt and water (ex. hydrochloric acid and sodium hydroxide)  net ionic for strong base and strong acid: neutralization reaction H + (aq) + OH -  H 2 O (l)

7. Acids and Bases: The Bronsted- Lowry Definition  An acid is a proton donor.  A base is a proton acceptor.  Acid-base reactions involve the transfer of a proton from an acid to a base to form a new acid and a new base. It is written as an equilibrium reaction and the equilibrium favors the weaker acid and base. can predict favorability can predict favorability

8. Acids and Bases: The Bronsted- Lowry Definition  Acids capable of transferring two or more H + ions react with water in multiple steps. Different steps may favor different sides of equilibrium. Sulfuric acid is capable of transferring two protons. The first step is product-favored but the second step is reactant-favored. Sulfuric acid is capable of transferring two protons. The first step is product-favored but the second step is reactant-favored.

9. Acids and Bases: The Bronsted- Lowry Definition  Some substances are amphiprotic and can function as either an acid or a base. Water is a typical example.

10. Practice Problem  Write the balanced, overall equation and the net ionic equation for the reaction of magnesium hydroxide with hydrochloric acid.

11. Oxides of Nonmetals  Nonmetal oxide + Water  Acid  Carbon dioxide reacts with water to form carbonic acid, which then ionizes slightly to form hydrogen ion and bicarbonate ion.  Bicarbonate ion can further ionize to form carbonate. (CO 2 is an acidic oxide) CO 2 + H 2 O  H 2 CO 3 H 2 CO 3  H + + HCO 3 - HCO 3 -  H + + CO 3 2-

12. Oxides of Metals  metal oxide + water  base CaO(s) + H 2 O(l)  Ca(OH) 2 (s) CaO(s) + H 2 O(l)  Ca(OH) 2 (s) oxides of metals are called basic oxides oxides of metals are called basic oxides  metal oxide + nonmetal oxide  salt 6CaO(s) + P 4 O 10 (s)  2Ca 3 (PO 4 ) 2 (s) 6CaO(s) + P 4 O 10 (s)  2Ca 3 (PO 4 ) 2 (s)

13. 3.8 Gas-Forming Reactions  Formation of a gas: gases may form directly in a double replacement reaction or can form from the decomposition of a product such as carbonic acid or sulfurous acid (table on page 140) often metal carbonates and acids often metal carbonates and acids Ex. Excess hydrochloric acid solution is added to a solution of potassium sulfite. H + + SO 3 -2  H 2 O (l) + SO 2(g)

14. Classifying Exchange Reactions  CuCO 3 (s) + H 2 SO 4 (aq)   Ba(OH) 2 (s) + HNO 3 (aq)   CuCl 2 (aq) + (NH 4 ) 2 S(aq) 

15. 3.9 Oxidation-Reduction Reactions  These reactions involve the transfer for electrons. The oxidation numbers of at least two elements must change. These may be single replacement, combination, and decomposition reactions. When a problem mentions an acidic or basic solution, it is probably redox.

16. Oxidation-Reduction Reactions  A substance that loses electrons is oxidized and is the reducing agent.  A substance that gains electrons is reduced and is the oxidizing agent. LEO goes GER If one substance is oxidized, another substance must be reduced. Hence, redox reactions!

17. Oxidation-Reduction Reactions 2Ag + + Cu  2Ag + Cu +2 Oxygen may not be present; but a transfer of electrons results in a charge reduction. Silver ion accepts electrons from copper and is reduced to silver (silver ion is the oxidizing agent). Copper donates electrons to silver ion and is oxidized to copper (II) ion and is the reducing agent.

18. Assigning Oxidation States  The oxidation state of… an atom in an element is zero (Na, O 2 ) an atom in an element is zero (Na, O 2 ) monatomic ion is same as charge (Na + ) monatomic ion is same as charge (Na + ) fluorine always has an oxidation number of -1 fluorine always has an oxidation number of -1 oxygen is usually -2 except for peroxides/fluorine oxygen is usually -2 except for peroxides/fluorine Cl, Br, and I are -1 except with oxygen or fluorine Cl, Br, and I are -1 except with oxygen or fluorine hydrogen is +1 in covalent compounds, -1 in binary hydrides, such as NaH hydrogen is +1 in covalent compounds, -1 in binary hydrides, such as NaH In a compound, the sum must be zero, KMnO 4 In a compound, the sum must be zero, KMnO 4 For ions, sum must equal overall charge, Cr 2 O 7 -2 For ions, sum must equal overall charge, Cr 2 O 7 -2

19. Determining Oxidation Numbers  Assign an oxidation number to the underlined atom in each ion or molecule. Fe 2 O 3 Fe 2 O 3 H 2 SO 4 H 2 SO 4 CO 3 2- CO 3 2- NO 2 - NO 2 -

20. 3.10 Classifying Reactions in Aqueous Solution  Precipitation Reactions: Ions combine in solution to form an insoluble reaction product.  Acid-Base Reactions: Water is a product of many acid-base reactions, and the cation of the base and the anion of the acid form a salt.  Gas-Forming Reactions: often involve metal carbonates and acids  Oxidation-Reduction: NOT ion exchange; electrons are transferred

21. Homework  After reading Sections 3.7-3.10, you should be able to do the following…  P. 154 (39-48)