1. CHAPTER 4 Aqueous Reactions and Solution Stoichiometry 1

2. GENERAL PROPERTIES OF AQUEOUS SOLUTIONS A solution is a homogeneous mixture of two or more pure substances. In a solution, the solute is dissolved in the solvent. 2

3. GENERAL PROPERTIES OF AQUEOUS SOLUTIONS An electrolyte is a substance that dissociates into ions when dissolve in water. 3

4. GENERAL PROPERTIES OF AQUEOUS SOLUTIONS A nonelectrolyte is a substance that does not dissociate into ions when dissolved in water. 4

5. GENERAL PROPERTIES OF AQUEOUS SOLUTIONS A strong electrolyte exists in solution completely or nearly completely as ions. 5

6. GENERAL PROPERTIES OF AQUEOUS SOLUTIONS 6

7. A weak electrolyte is a solute that exists in solution mostly in the form of molecules. 7

8. PRECIPITATION REACTIONS A reaction that results in the formation of an insoluble product is called a precipitation reaction 8

9. PRECIPITATION REACTIONS 9

10. In order to write an accurate equation for a precipitation reaction, you need to follow these steps: 1) Write a balanced molecular equation. 2) Dissociate all strong electrolytes. 3) Cross out the spectator ions. 4) Write the net ionic equation with whatever is left over. 10

11. ACID-BASE REACTIONS Acids are substances that ionize in aqueous solution to form hydrogen ions. There are seven strong acids: Hydrochloric (HCl) Hydrobromic (HBr) Hydroioidic (HI) Chloric (HClO 3 ) Perchloric (HClO 4 ) Nitric (HNO 3 ) Sulfuric (H 2 SO 4 ) 11

12. ACID-BASE REACTIONS Bases are substances that accept H + ions and produce hydroxide (OH - ) ions when they dissolve in water. The strong bases are the soluble metal salts of the hydroxide ion: Alkali metals Calcium Strontium Barium 12

13. ACID-BASE REACTIONS In an acid-base reaction, the acid donates a proton (H + ) to the base. 13

14. ACID-BASE REACTIONS When a solution of an acid and a solution of a base are mixed, a neutralization reaction occurs. HCl (aq) + NaOH (aq) → H 2 O (l) + NaCl (aq) When a strong acid and a strong base are mixed, water and a salt are produced. 14

15. ACID-BASE REACTIONS Some reactions can occur between acids and other species that produce a gas. CaCO 3 (s) + HCl (aq) → CaCl 2 (aq) + CO 2 (g) + H 2 O (l) 15

16. OXIDATION-REDUCTION REACTIONS A reaction in which electrons are transferred is called an oxidation-reduction, or redox, reaction. Loss of electrons is called oxidation. The gain of electrons is called reduction. 16

17. OXIDATION-REDUCTION REACTIONS The rules for assigning oxidation numbers are as follows: 1.For an atom in its elemental form, the oxidation number is always zero. 2.For any monatomic ion, the oxidation number equals the charge on the ion. 3.Nonmetals usually have negative oxidation numbers, although they can sometimes be positive. 17

18. OXIDATION-REDUCTION REACTIONS 4.The oxidation number of oxygen is usually -2, except in the peroxide ion (O 2 2- ) when it is -1. 5.The oxidation number of hydrogen is +1 when it is bonded to nonmetals and -1 when it is bonded to metals. 6.The oxidation number of fluorine is always -1 7.The sum of the oxidation numbers in a neutral compound is zero. The sum of the oxidation numbers in a polyatomic ion equals the charge on the ion. 18

19. OXIDATION-REDUCTION REACTIONS In order to determine whether or not a single-replacement reaction will occur, you need to look at the activity series of the elements. Any metal on the list can be oxidized by the ions of elements below it. 19

20. OXIDATION-REDUCTION REACTIONS 20

21. CONCENTRATIONS OF SOLUTIONS Molarity (M) expresses the concentration of a solution as the number of moles of solute in a liter of solution (soln): moles of solute volume of solution in liters Molarity (M) = 21

22. CONCENTRATIONS OF SOLUTIONS To make a dilution of a solution with a known molarity, a simple equation is used: M conc x V conc = M dil x V dil 22

23. SOLUTION STOICHIOMETRY AND CHEMICAL ANALYSIS 23

24. SOLUTION STOICHIOMETRY AND CHEMICAL ANALYSIS Titration is an analytical technique in which one can calculate the concentration of a solute in a solution. 24