1. Hydrochloric acid is mixed with aqueous sodium bicarbonate Molecular Equation

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Horatio Hugh Dickerson
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1 NAME Hr Chapter 4 Aqueous Reactions and Solution Chemistry Practice A (Part 1 = Obj. 1-3) (Part 2 = Obj. 4-6) Objective 1: Electrolytes, Acids, and Bases a. Indicate whether each of the following is strong, weak, or non-electrolyte. 1. hydrochloric acid 2. acetic acid 3. ammonia 4. potassium chloride 5. methane gas 6.. Magnesium Hydroxide 7. hydrophosphoric acid 8. ethanol, CH3CH2OH 9. hydrochloric acid 10. Lithium hydroxide b. Write, using symbols, the ions formed by the following electrolytes when they dissociate or ionize. Also indicate the quantity formed. 1. sulfuric acid 2. magnesium hydroxide 3. aluminum sulfate 4. chromic acid 5. aluminum phosphate 6. sodium phosphide c. Identify the following substances as an acid, base, or salt. 1. HC 2 H 3 O 2 2. NaCl 3. NH 3 4. CH 3 COOH 5. NaOH 6. CH 3 CH 2 CH 2 COOH 7. MgCl 2 8. H 3 PO 3 9. NH 4 OH 10. H 2 S 1

2 Objective 2: Precipitation Reactions and Ionic Equations Predict the driving force of metathesis reactions, including both neutralization and precipitation reactions, and write balanced chemical equations for them. The use of the solubility rules is necessary to predict the precipitation product. 1. Hydrochloric acid is mixed with aqueous sodium bicarbonate Equation Equation 2. Perchloric acid and barium hydroxide solutions are mixed Equation Equation: 3. Solutions of sodium bromide and silver nitrate are mixed Equation Equation 4. Aqueous nickel (II) chloride + aqueous sodium phosphate Equation Net ionic Equation 5. Hydrofluoric acid reacts with aqueous lithium sulfide Equation : 2

3 6. Magnesium bicarbonate reacts with hydrochloric acid 7. Solutions of lead II acetate reacts with barium chloride. 8. Calcium hydroxide reacts with acetic acid Net ionic Objective 3: Oxidation and Reduction a. Assign oxidation numbers to atoms in molecules and ions. Determine the oxidation number for the indicated element in each of the following compounds: C in C 2 O 4 2. As in As 4 3. O in K 2 O 2 4. Na in NaH S in SO P in PO 4 3

4 b. Use the activity series to predict whether a reaction will occur when a metal is added to an aqueous solution of either a metal salt or an acid, and write the balanced molecular and net ionic equations for the reaction. Include adjectives! 1. Iron metal is added to a solution of copper (II) nitrate 2. Zinc metal is added to a solution of hydrochloric acid 3. Aluminum metal is added to nickel II sulfate solution 4. Potassium metal is added to water b. Identify the oxidizing agent and reducing agent in a redox reaction. 1. Ni(s) + Cl 2 (g) NiCl 2 (s) Oxidizing agent Reducing agent 2. 3 Fe(NO 3 ) 2 (aq) + 2Al(s) 3Fe(s) + 2Al(NO 3 ) 3 (aq) Oxidizing agent Reducing agent 3. Mg(s) + PbCl 2 (g) MgCl 2 (aq) + Pb (s) Oxidizing agent Reducing agent 4

5 4. Ni(s) + 4 HNO 3 (aq) Ni(NO 3 ) 2 (aq) + 2 H 2 O(l) + 2 NO 2 (g) Oxidizing agent Reducing agent c. Balance simple redox reactions by the half reaction method. 1. MnO CH 3 OH Mn +2 + HCO 2 H (acidic soln) 2. As 2 O 3 + NO 3-1 H 3 AsO 4 + N 2 O 3 (acidic soln) 3. H 2 O 2 + Cl 2 O 7 ClO O 2 (basic soln) 5

6 Objective 4: Concentrations of Solutions a. Calculate molarity, solution volume, or number of moles, and number of grams of solute given any two of these quantities. INCLUDE UNITS IN PROBLEM AND IN ANSWER. 1. What is the molarity of an ethanol (C 2 H 6 O) solution containing 10.0 g of ethanol in water with a total volume of 100 ml? 2. How many grams of hydrochloric acid are contained in 500 ml of a M HCl solution? 3. What is the molarity of Na + ions in a 0.02 M sodium phosphate solution? 4. What is the molarity of an copper II sulfate pentahydride solution containing 5.25 g of the solid salt in enough water to make a total volume of 750 ml? 5. How many grams of potassium permanganate are contained in 430 ml of a 1.5 M aqueous solution? 6. What is the molarity of barium ions in a 0.04 M barium phosphate solution? b. Calculate the volume of a more concentrated solution that must be diluted to obtain a given quantity of a more dilute solution. 1. What is the molarity of a solution of NaOH formed by diluting 125 ml of a 3.0 M NaOH solution to 500 ml? 6

7 2. How many milliliters of 3.0 M sulfuric acid are needed to prepare 800 ml of 0.01M sulfuric acid solution? 3. What is the molarity of a solution of NaOH formed by diluting 410 ml of a 4.5 M NaOH solution to 1600 ml? 4. How many milliliters of 6.0 M sulfuric acid are needed to prepare 700 ml of 2.15 M sulfuric acid solution? Objective 5: Solution Stoichiometry a. Calculate the volume or mass of a solution required to react with a volume or mass of a different solution using molarity and the stoichiometry of the reaction. 1. How many liters of M HCl(aq) are needed to react completely with 500 ml of a 0.15 M Pb(NO 3 ) 2 (aq)? 2. What mass of calcium chloride is needed to precipitate the silver ions from 20 ml of M silver nitrate solution? 3. How many milliliters of M mercury II acetate solution are needed to react completely with 15 ml of a 1.35 M aluminum chloride solution? 7

8 4. What mass of barium bromide is needed to precipitate the lead IV ions from 100 ml of M Lead IV nitrate solution? b. Calculate the concentration or mass of solute in a sample from titration data. 1. In the laboratory 6.82 g of strontium nitrate is dissolved in enough water to form 0.50 L. A L sample is withdrawn from this stock solution and titrated with a M solution of sodium chromate. What volume of sodium chromate solution is needed to precipitate the entire strontium ion? 2. The distinctive odor of vinegar is due to acetic acid. If 3.45 ml of vinegar needs 42.5 ml of M NaOH to reach the equivalence point in a titration, how many grams of acetic acid are in a 750 ml sample? 3. In the laboratory g of copper (II) sulfate pentahydrate is dissolved in enough water to form 500 ml. A L sample is withdrawn from this stock solution and titrated with a M solution of sodium phosphate. What volume of sodium phosphate solution is needed to precipitate the entire copper (II) ion? 8

9 4. A sample of solid calcium hydroxide is stirred in water at 30 C until the solution contains as much dissolved calcium hydroxide as it can hold. A 100 ml sample of this solution is withdrawn and titrated with 0.35 M hydrobromic acid. It requires 65.0 ml of the acid solution for neutralization. What is the molarity of the calcium hydroxide solution? What is the solubility of calcium hydroxide in water, at 30 C in grams of calcium hydroxide per 100 ml of solution? (work from problem above) Objective 6: Distributed Practice 1. Calculate the molecular formula, having been given the empirical formula and molecular weight. Styrene, a compound substance used to make Styrofoam cups and insulation, contains 92.3%C and 7.7% H by mass and has a molar mass of 104 g/mol. What is its molecular formula? 2. Calculate the empirical formula, having been given the appropriate data: Ethylene glycol, the substance used in automobile antifreeze, is composed of 38.7% C, 9.7% H, and 51.6% O by mass. Its molar mass is 62.1 g/mol. What is the empirical formula of ethylene glycol? What is its molecular formula? 9

10 3. How many grams of aluminum sulfate can form when 20 g of aluminum hydroxide and 35 g sulfuric acid are allowed to react? 4. How many grams of strontium hydroxide form when 40 g of strontium oxide and 70 g water are allowed to react? 5. When benzene (C 6 H 6 ) reacts with bromine (Br 2 ), bromobenzene (C 6 H 5 Br) and Hydrobromic acid (HBr) are produced. What is the theoretical yield of bromobenzene in this reaction when 30.0 g of benzene reacts with 65 g of bromine? If the actual yield of bromobenzene was 56.7 g, what was the percentage yield? 6. The decomposition of potassium chlorate is commonly used to prepare small amounts of oxygen gas in the laboratory. How many grams of oxygen can be prepared from 4.5 grams of potassium chlorate? What is the percent yield if your actual yield generated 1.50 g of oxygen gas? 10

11 Integrative exercise. 1. The arsenic in a 1.22 g sample of a pesticide was converted to AsO 4-3 by suitable chemical treatment. It was then titrated using Ag + to form Ag 3 AsO 4 as a precipitate. i. What is the oxidation state of As in AsO 4-3? ii. Name Ag 3 AsO 4 by analogy to the corresponding compound containing phosphorus in place of arsenic. iii. If it took 25.0 ml of M Ag + to reach the equivalence point in this titration, what is the mass percentage of arsenic in the pesticide? 3. The mass percentage of chloride ion in a 25 ml sample of seawater was determined by titrating the sample with silver nitrate, precipitating silver chloride. It took ml of M silver nitrate to reach the equivalence point in the titration. What is the mass percentage of chloride ion in the seawater if its density if g/ml? 11

Chapter 4. Aqueous Reactions and Solution Stoichiometry

Chapter 4. Aqueous Reactions and Solution Stoichiometry Sample Exercise 4.1 (p. 127) The diagram below represents an aqueous solution of one of the following compounds: MgCl 2, KCl, or K 2 SO 4. Which solution does it best represent? Practice Exercise 1 (4.1)