1. All This STOICH has got me really burned up!!!

2. Important Terms!!! Solute – The substance that dissolves. Solvent – The substance that something dissolves in. Solution – The two together. Concentration – Amount of solute per given amount of solvent.

3. Water is considered by chemists to be the Universal Solvent. This is great when trying to mix up a solution but not so great when trying to keep our rivers and oceans clean. The bond angle of water is 105° The oxygen end of water is very negative making the H end slightly positive This is great when trying to mix up a solution but not so great when trying to keep our rivers and oceans clean. The bond angle of water is 105° The oxygen end of water is very negative making the H end slightly positive

4. The greek letter delta (δ) indicates a partial charge. Water is a POLAR molecule. A polar molecule is a molecule having an unequal charge distribution. One side is + and the other -. The polarity of water gives H 2 O it great ability to dissolve compounds. The δ + end of H 2 O are attracted to the – charged anion AND the δ - of H 2 O are attracted to the + charged cations (unlikes attract!!) Water is a POLAR molecule. A polar molecule is a molecule having an unequal charge distribution. One side is + and the other -. The polarity of water gives H 2 O it great ability to dissolve compounds. The δ + end of H 2 O are attracted to the – charged anion AND the δ - of H 2 O are attracted to the + charged cations (unlikes attract!!)

5. Hydration: the interaction between solute particles and water molecules. Water molecules surround ions or molecules due to electrostatic attraction between opposite charges.

6. Draw a molecule of sodium chloride showing the electron arrangement around the atoms.

7. Simulations http://phet.colorado.edu/en/simulations/category/chemistry 1.Salts and Solubility 2.Sugar and Salt Solution http://phet.colorado.edu/en/simulations/category/chemistry 1.Salts and Solubility 2.Sugar and Salt Solution

8. Draw a diagram showing the hydration of water with NaCl

10. Hydration Number Hydration number is the number of water molecules associated with a particular ion. (Usually, it requires 4 – 6 water molecules for a salt to “fall apart” or dissolve or dissociate) When salts (ionic compounds) dissolve, they break into their cations and anions. NH 4 NO 3 → ____________ + _____________ Hydration number is the number of water molecules associated with a particular ion. (Usually, it requires 4 – 6 water molecules for a salt to “fall apart” or dissolve or dissociate) When salts (ionic compounds) dissolve, they break into their cations and anions. NH 4 NO 3 → ____________ + _____________

11. If the molecule is polar, the water molecule will dissolve it. If nonpolar, water will NOT dissolve it! Ethyl alcohol and water (show how water is attracted to ethyl alcohol)

12. Many substances do not dissolve in water. Water will NOT dissolve animal fats, oils, etc. because they are Nonpolar. This means that this molecule does NOT have slight positive and negative charges and thus do not interact with H 2 O molecules. Many substances do not dissolve in water. Water will NOT dissolve animal fats, oils, etc. because they are Nonpolar. This means that this molecule does NOT have slight positive and negative charges and thus do not interact with H 2 O molecules.

13. A useful rule for predicting solubility… Like Dissolves Like In other words, polar dissolves polar or nonpolar dissolves nonpolar. In general, polar and ionic substances are soluble in water.

14. Electrolytes A solution is a homogeneous mixture (meaning it has the same composition throughout) with dissolved solute in a solvent. Some solutions will conduct electrical currents – this is called electrical conductivity. A solution that conducts an electrical current is called an ELECTROLYTE. There are three types of electrolytes. A solution is a homogeneous mixture (meaning it has the same composition throughout) with dissolved solute in a solvent. Some solutions will conduct electrical currents – this is called electrical conductivity. A solution that conducts an electrical current is called an ELECTROLYTE. There are three types of electrolytes.

15. Three Types of Electrolytes 1.Strong Electrolytes – conducts an electrical current efficiently 2.Weak Electrolyte – conducts a small electrical current. 3.NonElectrolyte – conducts NO electrical current.

16. The extent to which a solution conducts an electrical current depends on the NUMBER of dissolved ions in that solution!! In other words…if there are LOTS of dissolved ions floating around in the solution, then the solution will conduct electricity very well!!! (strong electrolyte)

17. Remember that an electrical current is flowing electrons. The electrons can be transported by ions so that the greater the number of ions, the greater the amount of current!

18. 1. Strong Electrolytes Depends on the solubility – the amount of a substance that dissolves in a given volume of solvent at a given temperature. Three Types of Strong Electrolytes 1. Soluble salts 2. Strong acids 3. Strong bases Depends on the solubility – the amount of a substance that dissolves in a given volume of solvent at a given temperature. Three Types of Strong Electrolytes 1. Soluble salts 2. Strong acids 3. Strong bases

19. A. Soluble Salts When salts dissolve in water, they dissociate completely so that large numbers of ions are present to carry the current. The more ions, the greater the conductivity.

20. B. Strong Acids… This work was done by the Swedish chemist Arrhenius – a Nobel prize winner for his work with acids. HCl → H +1 + Cl -1 HNO 3 → H +1 + NO 3 -1 H 2 SO 4 → 2H +1 + SO 4 -2 This work was done by the Swedish chemist Arrhenius – a Nobel prize winner for his work with acids. HCl → H +1 + Cl -1 HNO 3 → H +1 + NO 3 -1 H 2 SO 4 → 2H +1 + SO 4 -2

21. All of these – HCl, HNO 3 and H 2 SO 4 – have 100% dissociation. This means that for 100 molecules of HCl that are put into a solution, 100 H +1 and 100 Cl -1 will be produced. So, Arrhenius proposed that an ACID is a substance that produces H +1 ions (protons) in aqueous solutions. HCl, HNO 3, and H 2 SO 4 are all strong acids and therefore strong electrolytes. This means that for 100 molecules of HCl that are put into a solution, 100 H +1 and 100 Cl -1 will be produced. So, Arrhenius proposed that an ACID is a substance that produces H +1 ions (protons) in aqueous solutions. HCl, HNO 3, and H 2 SO 4 are all strong acids and therefore strong electrolytes.

22. C. Strong Bases Strong bases contain OH -1 (hydroxide) and completely dissociate (like strong acids) The 2 most common strong bases: NaOH → KOH → Strong bases contain OH -1 (hydroxide) and completely dissociate (like strong acids) The 2 most common strong bases: NaOH → KOH →

24. Weak acids are weak electrolytes Acetic acid (vinegar) HC 2 H 3 O 2 → __________ + ___________ With weak acids, only a relatively small percentage of molecules dissociate ( compared to 100% for strong acids ). So, for a weak acid (HX) that dissociates 1%, if 100 molecules of weak acid were dissolved in water, approximately 99 molecules remain intact and one will dissociate into H +1 and X -1. So…weak acids dissociate only slightly in aqueous solutions! Weak acids are weak electrolytes Acetic acid (vinegar) HC 2 H 3 O 2 → __________ + ___________ With weak acids, only a relatively small percentage of molecules dissociate ( compared to 100% for strong acids ). So, for a weak acid (HX) that dissociates 1%, if 100 molecules of weak acid were dissolved in water, approximately 99 molecules remain intact and one will dissociate into H +1 and X -1. So…weak acids dissociate only slightly in aqueous solutions!

25. Three examples of weak acids… 1.Benzoic acid HC 7 H 5 O 2 → 2. Carbonic acid H 2 CO 3 → 3. Hydrosulfuric acid H 2 S → 1.Benzoic acid HC 7 H 5 O 2 → 2. Carbonic acid H 2 CO 3 → 3. Hydrosulfuric acid H 2 S →

26. B. Weak Bases Weak bases also dissociate to small extents. The most common weak base is ammonia (NH 3 ) NH 3 + H 2 O → _________ + __________ Note: Ammonium ion – NH 4 + Ammonia – NH 3 a polar compound. Weak bases also dissociate to small extents. The most common weak base is ammonia (NH 3 ) NH 3 + H 2 O → _________ + __________ Note: Ammonium ion – NH 4 + Ammonia – NH 3 a polar compound.

27. Concentrations of Solutions There are three common types of concentrations: 1.MOLARITY = 2. MOLALITY = 3. NORMALITY = omit this!!!! Equivalents / liter Similar to M but, specific to a given reaction! There are three common types of concentrations: 1.MOLARITY = 2. MOLALITY = 3. NORMALITY = omit this!!!! Equivalents / liter Similar to M but, specific to a given reaction!

28. Molarity is the most commonly used concentration in the happy world of chemistry. A 1-Molar solution (or 1 M) of NaCl would contain 1 mole of NaCl in 1 Liter of water. A 2-Molar solution would contain 2 moles of solute in 1 Liter of water. Or 1 mole of solute in 0.5 liter of water Java - molarity A 1-Molar solution (or 1 M) of NaCl would contain 1 mole of NaCl in 1 Liter of water. A 2-Molar solution would contain 2 moles of solute in 1 Liter of water. Or 1 mole of solute in 0.5 liter of water Java - molarity

29. The Exciting Molarity formula M = #moles solute / #liters solution A 0.5M solution of NaCl means: Notice that this is a conversion factor between moles solute and liters solution! We can use it to convert a given volume to number of moles or given moles to volume!! 0.5 mol NaCl 1 L solution

30. Calculate the Molarity of a solution prepared by dissolving 11.5 g of solid NaOH in enough water to make 1.5 L of solution.

31. Calculate the Molarity of a solution prepared by bubbling 1.56 g of HCl into enough water to make 26.8 mL of solution.

32. A studious honors chem student dissolves 63 g of C 6 H 12 O 6 in 700 mL of water. Find the M.

33. How many molecules of glucose are present in 200 mL of a 0.5-Molar solution?

34. How many grams of potassium chromate are needed to make a 0.2-M solution in 250 mL of water?

35. How much water is needed to produce a 0.4 M solution of 24 g of NaCl?

36. Try This One!! 27.5 g of a solute is dissolved in 250 mL of water. The resulting solution is found to be 0.73 M. What is the formula weight of the solute?

38. Calculate the mass of lead (II) iodide formed when 0.5 Liters of a 0.1 M solution of lead (II) nitrate reacts with excess KI. 1.Write the balanced equation 2.Find the moles of lead II nitrate in solution

39. 3. Determine the mole ratio of PbI 2 formed. 4. Determine the grams of ppt formed.

40. Determine the amount of silver replaced when 100 mL of a 0.2 M solution of silver nitrate reacts with excess Ca.

41. Ionic Reactions Ionic Reactions are important to chemists because they actually show or tell the chemist what is happening in that reaction or in that beaker.

42. Think about what is actually happening in the beaker! Na 3 PO 4 → 3Na + + PO 4 -3 Mg(NO 3 ) 2 → Mg +2 + 2NO 3 - What happens next?

43. Sodium phosphate and magnesium nitrate yields magnesium phosphate and aluminum nitrate STEP 1: Write the balanced equation: This is called the Molecular equation: it gives the overall reaction stoichiometry but not necessarily the actual forms of the reactants and products in the solution.

44. STEP 2: Identify the insoluble product Use the solubility rules or the chart on the back of the Chem Helper The insoluble product is _________________

45. Step 3: Write the complete ionic reaction Complete ionic reaction: represents all reactants and products that are strong electrolytes as ions.

46. Step 4: Identify the spectator ions Spectator ions are ions that do not participate in the reaction and are called spectator ions (ions that are the same on both sides) The spectator ions in this reaction are ___________ and ___________.

47. Step 5: Write the net ionic equation Net ionic equation includes only those components undergoing a change. Spectator ions are never included (only the ions forming a solid are included!!!)

48. The exciting World of Oxidation & Reduction Oxidation = Loss of electrons; the element becomes more positive. Reduction = Gain of electrons; the element becomes more negative. OIL RIG or LEO the lion goes GER Oxidation = Loss of electrons; the element becomes more positive. Reduction = Gain of electrons; the element becomes more negative. OIL RIG or LEO the lion goes GER Oxidation Oxidized Reducing Agent Reduction Reduced Oxidizing Agent

49. Fe + O 2 → Fe 2 O 3 Iron goes from 0 charge to +3 – so Fe is oxidized. (And is the reducing agent). Oxygen goes from 0 charge to -2 – so O 2 is reduced. (And is the oxidizing agent).

50. Oxidation numbers are real or apparent charges on atoms, ions and molecules. They are usually used in Redox equations to keep track of e - lost and gained. You have been using these without knowing it!!! The “II” in Fe(II) and the IV in Ti(IV) are the oxidation numbers for the ions! Charges are “apparent” in covalent compounds – since we know there are no ions present.

51. Rules for Assigning Oxidation Numbers 1.Oxidation number of a free element = 0. 2.The oxidation number of a monoatomic ion is equal to its charge. 3.The algebraic sum of the oxidation numbers of the atoms in a compound = 0. 4.Hydrogen in a compound = +1 5.Oxygen in a compound = -2 6.Algebraic sum of a polyatomic ion is equal to its charge. 1.Oxidation number of a free element = 0. 2.The oxidation number of a monoatomic ion is equal to its charge. 3.The algebraic sum of the oxidation numbers of the atoms in a compound = 0. 4.Hydrogen in a compound = +1 5.Oxygen in a compound = -2 6.Algebraic sum of a polyatomic ion is equal to its charge.

52. Quick and dirty RULES 1.Free elements = 0 2.Monoatomic ions = charge 3.Compounds = 0 4.H = +1 5.O = -2 6.Polyatomic ions = charge 1.Free elements = 0 2.Monoatomic ions = charge 3.Compounds = 0 4.H = +1 5.O = -2 6.Polyatomic ions = charge

53. EXAMPLES ZnZn +2 Cl 2 Cl - P 2 O 5 PO 4 -3

54. More fun examples of oxidation numbers… NH 3 NH 4 + H 2 HBr O 2 NaClO 4

55. CH 4 + 2O 2 → CO 2 + 2H 2 O Note that Carbon goes from -4 to +4. Carbon must lose electrons. Carbon undergoes oxidation Carbon is oxidized Carbon is the reducing agent (e- donor) Note that Carbon goes from -4 to +4. Carbon must lose electrons. Carbon undergoes oxidation Carbon is oxidized Carbon is the reducing agent (e- donor)

56. Note that Oxygen goes from 0 to -2 (-8 total) Oxygen must be gaining electrons Oxygen undergoes reduction. Oxygen is reduced. Oxygen is the oxidizing agent. Oxygen must be gaining electrons Oxygen undergoes reduction. Oxygen is reduced. Oxygen is the oxidizing agent.

57. Write the REDOX equations… Oxidation: Reduction: Oxidation: Reduction:

58. 2Al + 3I 2 → 2AlI 3 Oxidation Equation: Reduction Equation: Oxidation Equation: Reduction Equation:

59. PbO + CO → Pb + CO 2 Oxidation equation: Reduction Equation: Oxidation equation: Reduction Equation:

60. End Here or Continue!

61. Half Reaction Method of Balancing Redox Equations in an acid FIVE STEPS: 1.Write the oxidation and reduction half reactions. 2.For each half-reaction: a. balance all elements except H and O b. Balance O using H 2 O c. Balance H using H +1 d. Balance the charge using e- 3. Multiply to get the number of e- equal. 4. Add the half reactions and cancel identical species. 5. Check that the elements and charges are balanced. FIVE STEPS: 1.Write the oxidation and reduction half reactions. 2.For each half-reaction: a. balance all elements except H and O b. Balance O using H 2 O c. Balance H using H +1 d. Balance the charge using e- 3. Multiply to get the number of e- equal. 4. Add the half reactions and cancel identical species. 5. Check that the elements and charges are balanced.

62. MnO 4 -1 + Fe +2 → Fe +3 + Mn +2

63. H +1 + Cr 2 O 7 -2 + C 2 H 5 OH → Cr +3 + CO 2 + H 2 O