1. Aqueous Reactions and Solution Stoichiometry
Chapter 4
Aqueous Reactions and Solution Stoichiometry

2. Properties of Aqueous Solutions
Weak electrolytes exist mostly as molecules

3. Precipitation Reactions
Precipitation reactions are those that result in the formation of an insoluble product

4. Precipitation Reactions
Precipitation reactions occur when certain pairs of oppositely charged ions attract to each other so strongly that they form an insoluble ionic solid

5. Precipitation Reactions
Solubility of a substance is the amount of that substance that can be dissolved in a given quantity of solvent

6. Precipitation Reactions
Any substance with a solubility less than 0.01mol/L will be referred to as insoluble

7. Precipitation Reactions
The solubility guidelines for common ionic compounds in water is organized by anions

8. Precipitation Reactions

9. Precipitation Reactions
To predict whether a precipitate will form when we mix aqueous solutions of electrolytes …

10. Precipitation Reactions
(1)note the ions present in the reactants
(2) consider combinations of anions and cations
(3) use the table to predict if any of the combinations are insoluble

11. Precipitation Reactions
Will a precipitate form when aqueous solution of magnesium nitrate and sodium hydroxide are mixed?

12. Precipitation Reactions
A molecular equation shows the complete chemical formulas of the reactants and the products

13. Precipitation Reactions
A complete ionic equation shows all strong electrolytes as ions rather than as compounds

14. Precipitation Reactions
Spectator ions are ions that appear as identical forms on both sides of the equation; they are present but don’t play a direct role in the reaction

15. Precipitation Reactions
Net ionic equations do not show spectator ions

16. Writing Net Ionic Equations
Write a balanced mol. E.q
Rewrite to show ions that form in solution
Cancel spectator ions

17. Acids produce H+ when dissolved in water Acids are proton donors
Acid-Base Reactions
Acids produce H+ when dissolved in water
Acids are proton donors

18. Bases produce OH- when they dissolve in water
Acid-Base Reactions
Bases accept H+ions
Bases produce OH- when they dissolve in water

19. Strong acids and bases are strong electrolytes – ionize completely
Acid-Base Reactions
Strong acids and bases are strong electrolytes – ionize completely

20. Acid-Base Reactions
Weak acids and bases are weak electrolytes – partially ionize ( do not write in ionized form)

21. List Strong Acids and Bases
Acid-Base Reactions
List Strong Acids and Bases

22. Acid-Base Reactions Figure 04-T02 Title: Table 4.2 Caption:
Common Strong Acids and Bases
Notes:
Keywords:

23. Identifying Strong, Weak, and Non Electrolytes Chart
Ionic
Soluble
N/A
Insoluble
Molecular
Strong Acids
Weak Acids Weak Bases (NH3)
All other compounds

24. Classifying SE, WE, or NE
1. Is it ionic or molecular?
2. If ionic – is it soluble?
3. If molecular – is it an acid?
4. If an acid – strong or weak?
5. Is it weak base NH3?
6. Everything else is a non electrolyte

25. Acid-Base Reactions
A neutralization reaction occurs when an acid and base are mixed producing water and salt
Salt means any ionic compound whose cation comes from the base and anion from the acid

26. Acid-Base Reactions
Reactions with the S2- ion or CO32- ion with acids will form gases with low solubility in water

27. Oxidation Numbers
Oxidation numbers of an atom in a substance are a hypothetical charge based on a set of rules.
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

28. Oxidation Numbers
3. Nonmetals usually have negative oxidation numbers.
a. O is –2 except in peroxides where O22-
giving each O –1.
b. H is +1 with nonmetals and –1 with
metals .
c. F is –1 in all compounds. Other halogens have –1
except when combined with oxygen they have
positive oxidation states.

29. Oxidation Numbers
4. The sum of oxidation numbers of all atoms in a neutral compound is 0.
The sum of oxidation numbers in a polyatomic ion is equal to the charge of the ion.

30. Oxidation-Reduction Reactions
Reactions where electrons are transferred between reactants

31. Oxidation-Reduction Reactions
Oxidized – when an atom, ion, or molecule becomes more positively charged (lost e-)
Reducing Agent = the substance that is oxidized

32. Oxidation-Reduction Reactions
Reduced – when an atom, ion, or molecule has become more negative (gain e-)
Oxidizing agent = the substance that is reduced

33. Oxidation-Reduction Reactions
Determine oxidation numbers, then identify the oxidizing agent and reducing agent in the rxn below.
2Ca(s) + O2(g)  2CaO(s)
Figure 04-12
Title:
Oxidation of calcium metal by molecular oxygen.
Caption:
The oxidation involves transfer of electrons from the metal to O2, eventually leading to formation of CaO.
Notes:
Keywords:

34. Oxidation-Reduction Reactions
A single replacement rxn is when an ion in solution is replaced through oxidation of an element

35. Oxidation-Reduction Reactions
Activity series is a list of metals arranged in order of decreasing ease of oxidation
Any metal on the list can be oxidized by the ions of elements below it.

37. Concentration of Solutions
Molarity (M)
= moles of solute / L soln

38. Making a Solution: How do you make a 250.0mL soln of 0.1M CuSO4?
Figure 04-16
Title:
Procedure for preparation of L of 1.00 M solution of CuSO4.
Caption:
(a) Weigh out mol (39.9 g) of CuSO4 (formula weight = amu). (b) Put the CuSO4 (solute) into a 250-mL volumetric flask, and add a small quantity of water. (c) Dissolve the solute by swirling the flask. (d) Add more water until the solution just reaches the calibration mark etched on the neck of the flask. Shake the stoppered flask to ensure complete mixing.
Notes:
Keywords:

39. Concentration of Solutions
Electrolytes and Concentration:
When an ionic compound dissolves, the relative concentration of ion depends on the chemical formula

40. Concentration of Solutions
A dilution can be made to concentrated stock solutions by adding water to the solutions, and therefore making them less concentrated.
M1V1 = M2V2

41. Solution Stoichiometry
Use mole conversions (molarity, molar mass, etc.) and mole ratios to solve stoichiometry problems through DA

42. Solution Stoichiometry