Tentative Chapter Four Assignments and ScheduleAny and/or all problems will be collected each day and scored for correctness.

Date Bk Section Readings

Video Due Problems Comments

One 4.1 1 1,3,5,12,14,15,16,17 Memorize the difference between strong, weak and non-electrolytes.

Two 4.2 2 19, 23, ,25, 27 , Precipitation Reactions: MEMORIZE your solubility rules!

Three 4.2 20, 22, 24, 26, 28 Solubility Rules Quiz, Pre-lab

Four Lab: “create x grams of a product”

Graded on how well you produce your amount of product.

Five 4.3 - Acid/Base Rxns

3 29,31, 33, 36,37,39 ,41

Memorize your strong acids and bases

Six 4.3 4 32, 34, 37, 40, 42, 91, 93

Strong acids and bases quiz

Seven 4.4 5 94, 47,50,52,54, Redox Reactions

Quiz on solubility rules. Acids and Bases: Memorize you Strong Acids and Strong Bases!

Eight 4.5 6 59, 62, 64, 66 Quiz on solubility rules (including strong acids and bases). Concentration and dilution

Nine 4.5 7 68, 70, 72, 74, 95 due on day ten

Ten Lab: Beer’s Law

Take home quiz

Eleven 4.6 78, 80, 81#, 83^, 86 Quiz on solubility rules (including strong acids and bases).

^Note the limited solubility of the strong base Ca(OH)2 in “d” of this problem. Some textbooks do not call Ca(OH)2 a strong base because it is so sparsely soluble.

#81 was the source of an AP MC question in 1999.

Twelve Lab: Standardization of a Solution of NaOH

Thirteen 4.6 Practice test assigned

Quiz on Solubility Rules and Strong Acids/Bases

Fourteen Review Day Practice Test corrected in class.

Take Home Quiz assigned

Fifteen Test, Ch1-4. Take home test due ____.Hints online.

Test is timed. MC and written.Also a take-home portion.

Chapter Four: Aqueous Reactions Example Problems.

What’s in this chapter?Things that dissolve in water: Strong – Weak and Non- Electrolytes

3-kinds of reactions to identify and write:

A way to express concentration.A way to dilute a solution.Solution stoichiometry.

4.1 Electrolytes…what are they?

What dissolved species are present in a solution of (a) KCN

(b) NaClO4?

Which solute will cause the light bulb, in the experiment shown in figure 4.2 (or the demonstration shown in class), to glow more brightly, CH3OH or MgBr2?

What is the difference:Strong-Weak-Non-Electrolytes

There are three kinds of strong electrolytes we will learn about this in this chapter…what are they?

4.2 Precipitation Reactions1st Kind of Strong Electrolytes: Soluble Ionic CompoundsSo, which ones are soluble?

SE 4.1, p.125 (need the picture)The diagram represents and aqueous solution of one of the following compounds: MgCl2, KCl or K2SO4.Which solution does it best represent? Why?

SE 4.2: Classify the following ionic compounds as soluble or insoluble in water: (a) sodium carbonate (Na2CO3), (b) (PbSO4).c) cobalt(2)hydroxide d) barium nitratee) ammonium phosphate.

SE 4.3: (a) predict the identity of the precipitate that forms when solutions of BaCl2 and K2SO4 are mixed.

(b) write the balanced chemical equations for the reaction.

c) what compound precipitates when solutions of Fe2(SO4)3 and LiOH are mixed?

(d) Write a balanced equation for the reaction.

(e) Will a precipitate form when solutions of Ba(NO3)2 and KOH are mixed?

SE 4.4: Write the net ionic equation for the precipitation reaction that occurs when solution of calcium chloride and sodium carbonate are mixed.

PE 4.4: Write the net ionic equation for the precipitation reaction that occurs when aqueous solutions of silver nitrate and potassium phosphate are mixed.

4.3 Acid-Base Reactions2nd and 3rd Kinds of Strong Electrolytes: Strong Acids and BasesWhich are the strong acids?

Which are not strong?

What does it mean if an acid is _STRONG_?

Which of the following is a strong acid: H2SO3, HBr, HC2H3O2?

Which are the strong bases?

How can you easily memorize both the strong acids and bases?

SE 4.5: Need the picture on p.132. Which of the following diagrams represent aqueous solutions of three acids (HX, HY, and HZ) with water molecules omitted for clarity. Rank them from strongest to weakest.

SE 4.6: Classify each of the following dissolved substances as a strong electrolyte, weak electrolyte, or nonelectrolyte: CaCl2, HNO3, C2H5OH (ethanol), HCHO2 (Formic acid), KOH.

PE 4.6: Consider solutions in which 0.1mol of each of the following compounds is dissolved in 1.0L of water:Calcium nitrateGlucoseSodium acetateAcetic acidRank the solutions in order of increasing electrical conductivity based on the fact that the greater the number of ions in solutions, the greater the conductivity.

SE 4.7: (a) Write a balanced molecular equation for the reaction between aqueous solutions of acetic acid (HC2H3O2) and barium hydroxide (Ba(OH)2)

(b) Write the net ionic equation for this reaction

(a) Write a balanced molecular equation for the reaction of carbonic acid (H2CO3) and potassium hydroxide (KOH).

(b) Write the net ionic equation for this reaction.

**Gas Forming Reactions – Remember These!

Involving S-2

Involving CO3-2

Involving HCO3-

By analogy to examples already given in the text, predict what gas forms when Na2SO3(s) is treated with HCl(aq)

So, in conclusion, there are five anions to MEMORIZE that, when reacted with an acid, will form a gas…

a) what are these three anions?b) what gas does each form?

4.4 Oxidation-Reduction ReactionsWhat is a redox reaction?

How do you know if a redox reaction occurred?

So, to tell if a redox rxn occurs, we have four rules to MEMORIZE for assigning oxidation numbers:1)

2)

3) a)

b)

c)

4)

What noble gas element has the same number of electrons as the fluoride ion?What is the oxidation number of the species?

SE 4.8: Determine the oxidation number of sulfur in each of the following: a) H2Sb) S8

c) SCl2

d) Na2SO3 e) SO4

2-

SE 4.9: Write the balanced molecular and net ionic equation for the reaction of aluminum with hydrobromic acid. Identify what is oxidized and what is reduced.

Write the balanced molecular and net ionic equations for the reaction between magnesium and cobalt (II) sulfate.

What is oxidized and what is reduced in the reaction?

Using Table 4.5 (on page 143), identify which is more easily reduced, Mg2+ (aq) or Ni2+

(aq)?

SE 4.10: Using Table 4.5 (on page 143), will an aqueous solution of iron(II) chloride oxidize magnesium metal? If so, write the balanced molecular and net ionic equations for the reaction.

PE 4.10: Using Table 4.5 (on page 143), which of the following metals will be oxidized by Pb(NO3)2:

(a) Zn (b) Cu (c) Fe?

4.5 Concentrations of SolutionsWhat is molarity? What is the molarity triangle?

SE 4.11: Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate (Na2SO4) in enough water to form 125mL of the solution.

Calculate the molarity of a solution made by dissolving 80.00g of glucose (C6H12O6) in sufficient water to form exactly 100mL of solution.

SE 4.12: What are the molar concentrations of each of the ions present in a 0.025M aqueous solution of calcium nitrate?

What is the molar concentration of K+ ions in a 0.500M solution of potassium carbonate?

SE 4.13: How many grams of Na2SO4 are required to make 0.350L of 0.500M Na2SO4?

More sample problems:(a) How many grams of K2CO3 are there in 15mL of 0.50M K2CO3?

(b) How many milliliters of 0.50M K2CO3 solution are needed to provide 0.250 mol of this salt?

What is a dilution?What is the “dilution equation?”

SE 4.14: How many milliliters of 3.0M H2SO4 are needed to make 450mL of 0.10M H2SO4?

PE 4.14, more examples of molarity triangle problems:(a) What volume of 2.50M lead (II) nitrate solution contains 0.0500 mol of Pb2+?

(b) How many milliliters of 5.0M K2Cr2O7 solution must be diluted to prepare 250mL of 0.10M solution?

(c) If 10.0 mL of a 10.0M stock solution of NaOH is diluted to 250mL, what is the concentration of the resulting stock solution?

4.6 Solution StoichiometryUsed to determine “how much” of a particular “ion” in a solution.What is a titration-type reaction?

What is the “equivalence point” of a titration?

SE 4.15: How many grams of Ca(OH)2 are needed to neutralize 25.0mL of 0.100M HNO3?

PE 4.15: (a) How many grams of NaOH are needed to neutralize 20.0mL of 0.15M H2SO4

solution?

(b) How many liters of 0.500M HCl(aq) are needed to react completely with 0.100 mol of Pb(NO3)2(aq), forming a precipitate of PbCl2(s)?

25.00mL of a 0.100M HBr solution is titrated with a 0.200M NaOH solution.How many mL of the NaOH solution are required to reach the equivalence point?

SE 4.16: The quantity of Cl-1 in a municipal water supply is determined by titrating the sample with Ag+. The reaction taking place during the titration is:

Ag+(aq) + Cl-(aq) --------- AgCl(s)The end point in this type of titration is marked by a change in color of a special type of indicator.

(a) How many grams of chloride ion are in a sample of the water is 20.2mL of 0.100M Ag+ is needed to react with all the chloride in the sample?

(b) If the sample has a mass of 10.0g, what percent Cl- does it contain?

PE 4.16: A sample of iron ore is dissolved in acid, and the iron is converted to Fe2+. The sample is titrated with 47.20 mL of 0.02240M MnO4

- solution. The oxidation-reduction reaction that occurs during the titration is as follows:

MnO4-(aq) + 5Fe2+(aq) + 8H+ -----------Mn2+(aq) + 5Fe3+(aq) + 4H2O(l)

(a) How many moles of MnO4- were added to the solution?

(b) How many moles of Fe2+ were in the sample?

(c) How many grams of iron were used in the sample?

(d) If the sample had a mass of 0.8890g, what is the percentage of iron in the sample?

SE 4.17One commercial method used to peel potatoes is to soak them in a solution of NaOH for a short time, remove them from the NaOH, and spray off the peel. The concentration of NaOH is normally in the range of 3 to 6M. The NaOH is analyzed periodically. In one such analysis, 45.7mL of 0.500M H2SO4 is required to neutralize a 20.0mL sample of NaOH solution. What is the concentration of the NaOH solution?

PE 4.17What is the molarity of an NaOH solution if 48.0mL is needed to neutralize 35.0mL of 0.144M H2SO4?

1 Redox Titration Question like 2007 and 2003B (#5 in both exams).

Look at the equation below:

a) What is the oxidation number of chromium in the dichromate, , ion?

b) Identify the oxidizing agent in the reaction represented above.

The mass of a sample of the iron II compound is carefully measured before the sample is dissolved in distilled water. The resulting solution is acidified with HCl(aq). The solution is then titrated with until the end point is reached.

Let the variables g, M and V be defined as follows:g= the mass, in grams, of the sample of the iron II compoundM= the molarity of the used as the titrantV= the volume, in liters, of added to reach the end point.

In terms of these variable, the number of moles of added to reach the end point of the titration is expressed as M x V. Using the variables defined above, the molar mass of iron (55.85 g mol-1) and the coefficients in the balanced chemical equation write the expression for each of the following quantities.

c) The number of moles of iron in the sample:

d) The mass of iron in the sample, in grams:

e) The mass percent of iron in the compound:

f) What effect would adding too little titrant have on the experimentally determined value of the mass percent of iron in the compound? Justify your answer.

2 Redox Titration Question like 2007 and 2003B (#5 in both exams).

A standardized solution of permanganate ion is used to determine the molar concentration of an unknown hydrogen peroxide, H2O2(aq), solution as indicated by the net ionic equation below:

A student places 50.0 mL of permanganate ion solution of known concentration into a buret. 20.0mL of H2O2 solution of unknown concentration is placed in a flask with 20.0mL of distilled water and 1.0mL of 5.0M H2SO4. In the titration, the KMnO4 solution is added to the solution containing H2O2.

a) What is the oxidation number of the oxygen atom in the peroxide, H2O2(aq), molecule?

b) Which is the reducing agent in the reaction above?

c) Describe the color change that occurs in the flask when the end point of the titration has been reached. Explain why the color of the solution changes at the end point.

d) What data must be collected in order to determine the molar concentration of the unknown H2O2 solution?

e) Without doing any calculations explain how to determine the molarity of the unknown H2O2 solution.

f) How would the calculation concentration of the H2O2 solution be affected if 4.0mL of H2SO4 was added to the H2O2 initially instead of 1.0mL? Explain your reasoning.

Solubility Question like 2002B, 2004, 2005 and 2006 (all #5)

5 unlabled bottles of clear solution are placed on a lab table, labeled A, B, C, D, E.

The bottles contain (in no particular order):Ca(NO3)2

Pb(NO3)2

Ag(NO3)NaIK2CO3

A chemistry student is assigned the task of identifying each solution and given equipment and known chemicals to perform the identification procedure.

a) When solution A is mixed with a small amount of 0.10M hydroiodic acid a bright yellow precipitate forms. Identify the contents of solution A.

b) Solutions B, C, D and E are also treated with 0.10M hydroiodic acid. Solution B forms a white precipitate and solution C bubbles. No visible reaction occurs to solutions D and E. Identify solutions B and C. Justify your answers.

c) Write the net ionic equations for the two reactions that identified solutions B and C above.

d) 10 drops of solution A are placed in solutions D and E. Describe any visible evidence of reaction(s) (if any) that occur. Justify your answer with an equation.

Chapter 1-4 Free Response Practice Test: Show all work and units for full credit.1. Answer the following questions about CuSO4(s) and its hydrate.

(a) Calculate the mass percent of sulfur in the hydrated form of the solid that has the formula CuSO45H2O

(b) When heated to 420.oC, CuSO45H2O (s) dehydrates completely as represented in the equation CuSO45H2O (s) CuSO4 (s) + 5H2O(g). If 1.21 g of CuSO45H2O (s) is heated to 420.oC, calculate the mass of CuSO4 (s) formed.

2. Answer the following questions about acetylsalicylic acid, the active ingredient in aspirin.(a) The amount of acetylsalicylic acid in a single aspirin tablet is 325 mg, yet the tablet has a

mass of 2.00 g. Calculate the mass percent of acetylsalicylic acid in the tablet.

(b) The elements contained in acetylsalicylic acid are hydrogen, carbon, and oxygen. The combustion of 3.000 g of the pure compound yields 1.200 g of water and 6.42 g of carbon dioxide. Calculate the mass, in g, of each element in the 3.000g sample.

3. The reaction between silver ion and solid nickel is represented by the following equation.2Ag+(aq) + Ni(s) Ni2+(aq) + 2Ag(s) A 4.50 g sample of Ni is combined with 550. mL of 0.150M AgNO3 at 25oC.

(a) Identify the limiting reactant. Show calculations to support you answer.

(b) On the basis on the limiting reactant that you identified in part (i), determine the value of the concentration of Ni2+ after the reaction is complete. Assume that volume change is negligible.

4. What is the empirical formula for a compound that contains 40% Ca, 12% C and 48% O?

5. Methanol (CH3OH) reacts with oxygen to produce carbon dioxide (CO2) and water. If 30.0g of methanol react with 32.0g of oxygen form 22.00g of CO2, what is

(a) The limiting reactant(b) The moles of each reactant and product that remain when the reaction is complete(c) The percent yield

A 0.450 g sample of anhydrous Na2Cr2O7, which contains an inert impurity, was dissolved in sufficient water to produce 100. mL of solution. A 20.0 mL portion of the solution was titrated with Cl-(aq). The balanced equation for the reaction that occurred is as follows.

The volume of 0.0150 M Cl-(aq) required to reach the equivalence point was 17.80 mL.(i) Identify the element that is reduced in the titration reaction.

(ii) For the titration at the equivalence point, calculate the number of moles of each of the following that reacted.* Cr2O7

2-(aq)*Cl-(aq)

(iii) Calculate the total number of moles of Cr2O72-(aq) that were present in the 100.

mL of prepared solution.

(iv) Calculate the mass percent of Na2Cr2O7(s) in the impure 0.450 g sample.

Really Fun Bonus QuestionA sample of 1.50g of lead II nitrate is mixed with 125mL of 0.100M sodium sulfate solution.

a. Write the complete molecular equation for the reaction that occursb. Write the complete ionic equation for the reaction that occursc. Write the net ionic equation for the reaction that occursd. Which is the limiting reactant in the reaction?e. What are the concentrations of all ions that remain in solution after the reaction is

complete?