Chemical Reactions. By: Jasmine Gilbert, Matt Huber and Dr. Faith Yarberry

Transcription

1 Chemical Reactions By: Jasmine Gilbert, Matt Huber and Dr. Faith Yarberry In this module the students will: Learn to identify a chemical reaction as a single displacement, double displacement, synthesis, or decomposition reaction. Learn to identify precipitation reactions and be able to utilize the solubility rules to determine the state of matter associated with each species in the reaction. Learn how to identify acid / base neutralization reactions, including esterfication and amide formation, and how to identify their products. Understand Oxidation-Reduction reactions. Reactions Page 1

2 Chemical Reactions Lecture Lesson 1: Double Displacement, Single Displacement, Synthesis, Decomposition? Reactions may be described in many ways. One way is to describe the reaction by what physically occurs during the reaction. Yet another way is to describe the reaction according to the chemical process it undergoes. Each of these will be discussed separately but overlaps will be shown where appropriate. Four terms are used to describe reactions by what physically occurs within the reaction equation. These four terms are Double Displacement, Single Displacement, Synthesis, and Decomposition. Double Displacement reactions, or metathesis reactions, are ones in which the cation swaps the anion it is attached to. In the picture below the man is the cation and the hat the anion. Notice that as the reaction proceeds from left to right, the cation simply swapped its anion. More commonly this reaction is illustrated using the general formula: Demonstration: Demonstration Preparation: AB + CD AD + CB Dissolve g cobalt (II) chloride hexahydrate, CoCl 2. 6 H 2 O, in enough water to make 50 ml of solution. Dissolve g sodium hydroxide, NaOH, in enough water to make 50 ml of solution. This generates heat so add the NaOH slowly to the water. Demonstration Materials: 0.1 M CoCl 2. 6 H 2 O 0.1 M NaOH Test tube 2 droppers Reactions Page 2

3 Procedure: 1. Add 20 drops of cobalt chloride hexahydrate to a test tube. Point out to the class that the solution is clear though tinted. 2. Add 20 drops of the sodium hydroxide to the test tube. Point out to the class that the solution is now opaque. Let them know that formation of a solid often indicates that a chemical reaction occurred. Observations: Cobalt chloride hexahydrate is a rose colored solution, sodium hydroxide is a clear solution. When combined they form a teal solution with a solid precipitate. The reaction is: CoCl 2 (aq) + 2 NaOH (aq) Co(OH) 2 (s) + 2 NaCl (aq) Precipitation reactions involving two ionic compounds are always double displacement reactions. Single Displacement reactions are reactions in which the cation of an ionic compound gains electrons to become a neutral element while the neutral element in the reaction dissolves to form a cation. In the diagram below the man in the red shirt represents the neutral element on the reactant side. As the reaction proceeds the man in the red shirt dissolves taking on the anion. As this occurs the other male changes from being a cation as a reactant to being neutral as a product. More commonly this reaction is illustrated using the general formula: Demonstration: Demonstration Materials: 1.1 M AgNO 3 Cu wire Test tube A + BY AY + B Reactions Page 3

4 Procedure: 1. Pass around a piece of copper wire. Have the students describe the material. 2. Pass around a solution of silver nitrate. Point out to the students that this solution is a clear, colorless solution. 3. Place a piece of copper wire into a test tube and cover the wire with aqueous silver nitrate. 4. Allow this reaction to sit until the end of class. Observations: The copper is a shiny, reddish-gold solid; the silver nitrate is a clear, colorless solution. As the reaction proceeds, the solid begins to turn grey which is the silver plating out onto the solid copper and the solution begins to take on a blue tint indicating that the copper is dissolving into solution. Cu (s) + 2 AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2 Ag (s) Single displacement reactions are an example of a redox reaction. Additionally, precipitation reactions involving an element and an ionic solution will always be single displacement reactions. If you would like an exciting video to illustrate a single displacement reaction, show the Brainiac Thermite video. The reaction: 2 Al (s) + Fe 2 O 3 (aq) Al 2 O 3 (s) + 2 Fe (molten) Another cool single displacement reaction occurs when magnesium burns in the presences of carbon dioxide. ( 2 Mg (s) + CO 2 (s) 2 MgO (s) + C (s) Synthesis reactions are the result of more than one reactant combining to form a single product. In the diagram below the reactant bird is wasting away. When the bird eats the worm, hence combines with the worm, you get a fat bird. The product bird is therefore the result of the skinny bird combining with the worm. Reactions Page 4

5 The most common way to illustrate this type of reaction is via the general reaction: A + B AB Demonstration: Demonstration Materials: Magnesium strip Bunsen burner Watch glass Tongs Procedure. 1. Pass a strip of magnesium around to your students for observation. 2. Warn your students to look at your face rather than the experiment. 3. With tongs grab a piece of magnesium 4. Place the magnesium into the flame of a Bunsen burner until it ignites. 5. Quickly move the magnesium over the watch glass to collect the reaction residue. 6. Pass the residue around to your students for observation. Observations: The magnesium is a shiny, silver solid that glows bright white when ignited. A white solid residue is the result of the reaction. 2 Mg (s) + O 2 (g) MgO (s) Reactions involving pure metals with oxygen are examples of synthesis reactions as well as redox reactions. Decomposition reactions occur when one reactant gives off two or more products. In the diagram below the reactant egg hatches to give two products, the egg shell plus turtle. The most common way to illustrate this type of reaction is via the general reaction: AB A + B Reactions Page 5

6 Demonstration: Demonstration Materials: Ammonium carbonate Test tube Test tube clamp Bunsen burner Lighter Procedure: 1. Add a small amount of ammonium carbonate to a test tube. 2. Pass the sample around for the students to make observations. (Smell, appearance) 3. Using test tube clamps, hold the test tube over the flame of a Bunsen burner. 4. Allow the solid to completely disappear. 5. Have a student waft a sample of the gases produced toward their nose and have them report their findings to the class 6. Have a student look at the top of the test tube and tell the class what they see. Observations: The ammonium carbonate reactant is a white solid. As this material is heated it decomposes to form three gases. The smell is indicative of ammonia gas being produced. The condensation at the top of the test tube is the result of water gas being generated and then the gas being cooled. The last product is difficult to detect and that is carbon dioxide. (NH 4 ) 2 CO 3 (s) 2 NH 3 (g) + H 2 O (g) + CO 2 (g) Lab #1 gives the student an opportunity to identify reactions as occurring by single displacement, double displacement, synthesis, or decomposition. It also give them the opportunity to predict the products for the reactions. Reactions Page 6

7 Lesson 2 Precipitation Reactions Lessons 2-4 include a second way to describe chemical reactions. This is accomplished by evaluating the they types of products formed or the oxidation states of the elements involved. There are three types of reactions that we will discuss: Precipitation reactions, Acid / Base Neutralization reactions (also described as dehydration reactions), and Oxidation- Reduction reactions. Precipitation reactions are reactions that produce a solid product. Many precipitation reactions involve inorganic chemicals. These reactions fall into the categories of double displacement or single displacement reactions. Examples of this reaction type include: and as discussed previously. CoCl 2 (aq) + 2 NaOH (aq) Co(OH) 2 (s) + 2 NaCl (aq) Cu (s) + 2 AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2 Ag (s) Another example is the reaction of lead (II) nitrate with potassium dichromate. K 2 Cr 2 O 7 (aq) + Pb(NO 3 ) 2 (aq) 2 KNO 3 (aq) + PbCr 2 O 7 (s) Again, the observation that leads to the identification of a reaction as a precipitation reaction is the formation of a solid referred to as a precipitate. How can the identity of the solid product be predicted in a double displacement reaction? Via the solubility rules which are listed in the table below. (They are listed in order of importance.) The compound will be If it contains Unless combined with Soluble (aq) + Group 1, NH Soluble (aq) NO - 3, C 2 H 3 O - 2, ClO - - 4, HCO Soluble (aq) Halides (F -, Cl -, Br -, I - ) Ag +, Pb 2+ 2+, Hg 2 Soluble (aq) 2- SO 4 Ag +, Pb 2+, Hg 2+ 2, Ca 2+, Sr 2+, Ba 2+ Insoluble (s) O 2-, OH - Ca 2+, Sr 2+, Ba 2+ Insoluble (s) All other anions Have your students predict the state of matter of the reactants and of the products in each of the following reactions and state whether the reaction is a precipitation reaction. (NH 4 ) 2 SO 4 + FeCl 2 FeSO NH 4 Cl AgNO 3 + NaCl AgCl + NaNO 3 2 NaOH + Mg(C 2 H 3 O 2 ) 2 2 NaC 2 H 3 O 2 + Mg(OH) 2 Reactions Page 7

8 Lesson 3 Acid / Base Neutralization Reactions Acid / Base Neutralization Reactions combine acid and base reactants to form water as one of the products. Example: HCl (aq) + NaOH (aq) H 2 O (l) + NaCl (aq) To be able to recognize a reaction as that between an acid and a base, it is necessary to be able to identify acids and bases. Demonstration: Demonstration Preparation: 1.1 M Barium hydroxide octahydrate dissolve 3.15 g barium hydroxide octahydrate in enough water to make 100 ml of solution 0.1 M Sulfuric acid slowly add 0.55 ml of concentrated sulfuric acid to 50 ml of water in a 100-mL volumetric flask. Cap and shake. Fill to the mark with water. Cap and shake. Reactions Page 8

9 Demonstration Materials: 0.1 M Barium hydroxide octahydrate 0.1 M sulfuric acid Buret 250 ml beaker Phenolphthalein indicator Electrode Stirring rod Procedure: 1. Give the student the formula of barium hydroxide and sulfuric acid and ask them to predict the product of the reaction. 2. To a 250-mL beaker add 30 ml of 0.1 M sulfuric acid. 3. To the beaker add 50 ml of water and 2 drops of phenolphthalein. 4. Ask the student for their opinion as why the water you just added should not make a difference in our reaction. (Point out to them that it is the sulfuric acid reacting with the sodium hydroxide that is important and that the moles of H 2 SO 4 did not change, only the concentration.) 5. Fill a buret with barium hydroxide. 6. Place the beaker under the buret and drop the buret tip so that it is just below the mouth of the beaker. 7. Place the electrodes down into the beaker and plug in the system. 8. Ask the students to explain why the light is currently glowing brightly. 9. Add the barium hydroxide 1 ml at a time for the first 25 ml. Ask the students to describe what they see. (light begins to dim as solid forms) 10. Add the last 5 ml drop-by-drop until the endpoint is reached (phenolphthalein will turn pink and remain pink for 30 seconds and the light will go out) 11. Ask your students to explain their observations. 12. Set the resultant material aside in a labeled container until the water evaporates off. The resultant barium sulfate must be disposed of properly. The two reactions above are straight forward acid/base neutralization reactions involving a strong acid and a strong base, but, many other very important reactions fall under the category of acid / base neutralization reactions. These include ester formation and amide formation which are reactions associated with biological systems. The remainder of this lesson focuses on these reactions. Reactions Page 9

10 Esters are the result of weak acids, containing the carboxylic acid functional group, combining with alcohols. Functional Groups an atom (or group of atoms and their bonds) that impart specific chemical and physical properties to a molecule Carboxylic Acid Alcohol Ester The carboxylic acid provides the hydrogen ion and the alcohol provides the hydroxide ion for water formation. Below is a reaction involving ester formation between salicylic acid and methanol. Reactions Page 10

11 Demonstration: Demonstration Materials: 0.1 g salicylic acid 10 drops methanol 2 Droppers Test tube 5 drops Conc. Sulfuric Acid Spatula Balance Weigh boat or paper 250-mL beaker Hot plate Thermometer Test tube clamps Test tube rack Demonstration Procedure 1. Prepare a warm water bath by filling a 250-ml beaker with water and heating the water to C. 2. Mass out 0.1 g salicylic acid and place it in a test tube. 3. Add 10 drops of methanol. 4. After combining the alcohol and acid, swirl the test tubes around to mix the contents thoroughly. 5. Using a new dropper add 5 drops of concentrated Sulfuric Acid to each test tube. Mix each solution. Caution: Concentrated sulfuric acid is corrosive and may cause severe burns. If exposed to the acid, immediately wash the exposed area for several minutes. 6. Place the test tube in the hot water bath for 10 minutes. After 10 minutes, remove the test tube carefully with a test tube holder and place it in the test tube rack. 7. Let it cool to room temperature before handling. 8. After the test tube has cooled, pass the ester around the class and have the waft to determine smell. Lab 2 gives the student the opportunity to form esters. Triglycerides, fats, are the result of ester formation between 3 fatty acids and glycerol which contains 3 alcohol groups. Reactions Page 11

12 Amide formation occurs between the hydrogen of an amine functional group and the hydroxide of a carboxylic acid functional group. Carboxylic Acid Amine Amide Proteins and Enzymes result from amide formation between carboxylic acid functional groups and the amine groups of amino acids. Amino Acid Reactions Page 12

13 Lesson 4 Oxidation-Reduction Reactions (Redox Reactions) Oxidation-Reduction reactions, also known as redox reactions, are reactions that involve a transfer of electrons as the reaction proceeds from reactants to products. This lesson will discuss two primary types of redox reactions. They include single displacement reactions and combustion reactions. These two types of reactions will be studied individually. Single displacement reactions If you look back at the formula for a single displacement reaction, A + BY AY + B, you will note that: The reactant that is in elemental form becomes a cation on the product side of the reaction The cation of the ionic compound on the reactant side is neutralized on the product side as it becomes an element. If you follow these alterations, it will be easy to identify this as a redox reaction and visualize the electron transfer. The simplest way to follow the alteration is to assign oxidation states to the elements that undergo the change. There are two rules of importance associated with single displacement reactions. 1) An element in its standard state, meaning that it is neutral, has an oxidation state of zero. 2) A monoatomic ion has an oxidation state equal to its charge. Let s just look at an example: Cu (s) + 2 AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2 Ag (s) By eliminating the nitrate ion, which does not undergo a change, the reaction becomes: Cu (s) + 2 Ag + (aq) Cu 2+ (aq) + 2 Ag (s) Now it s time to assign oxidation states to the reaction. Now to follow the alterations that occurred Cu (s) + 2 Ag + (aq) Cu 2+ (aq) + 2 Ag (s) Note: Copper lost 2 electrons as it moved from reactant side to product side and each silver atom gained 1 electron as it moved from reactant side to product side. Because one element gained Reactions Page 13

14 electrons and one element lost electrons, there was a transfer of electrons and this reaction is a redox reaction. There are four key terms used to describe a redox reaction. Element oxidized the element that loses electrons as it moves from reactant side to product side. Element reduced the element that gains electrons as it moves from reactant side to product side. Reducing reactant the reactant that causes an element to be reduced. (The reducing reactant will contain the element that is oxidized.) Oxidizing reactant the reactant that causes an element to be oxidized. (The oxidizing reactant will contain the element reduced.) Let s apply this terminology to the reaction we have been looking at. Combustion reactions of hydrocarbons A combustion reaction is one in which a hydrocarbon is combined with oxygen. The most common products of a combustion reaction are carbon dioxide and water though other compounds are possible. Hydrocarbons are compounds that are primarily composed of hydrogen and carbon, though other elements of sulfur, oxygen, and nitrogen, can be present. All combustion reactions are redox reactions. The oxygen acts as an oxidizing reactant to oxidize the carbon of the hydrocarbon. The hydrocarbon acts as the reducing reactant to reduce the oxidation state of oxygen. 2 C 8 H 18 (g) + 25 O 2 (g) 16 CO 2 (g) + 18 H 2 O (g) Reducing reactant oxidizing reactant C oxidized O reduced Reactions Page 14

15 Demonstration: Demonstration Materials 1 packet of active dry yeast 1 cup of very warm water (105 o F 115 o F) Kitchen thermometer 2 tablespoons of sugar Large rubber balloon 1-pint to 1-liter empty water bottle Procedure: 1. Add the 1 packet of dry yeast to the balloon. 2. Set the balloon aside. 3. Add the warm water to the bottle. 4. Add the 2 tablespoons of sugar to the bottle. 5. Attach the balloon to the mouth of the bottle. 6. Dump the yeast into the sugar solution and swish the bottle. 7. Set the bottle aside 8. After several minutes, you ll notice the balloon standing upright. 9. Give the students the reaction and ask them to identify the element oxidized, the element reduced, the oxidizing reactant and the reducing reactant Observations: As the yeast combines with the sugar solution bubbling will occur. Let your students know that bubbling is a sign of a chemical reaction. In this case the bubbling is the result of carbon dioxide being produced from the decomposition of the sugar. Yeast is simply a catalyst for this reaction. A catalyst is a material that speeds up reaction but its composition remains unchanged. 3 C 12 H 22 O 11 (aq) + 3 O 2 (g) 11 C 2 H 5 OH (aq) + 14 CO 2 (g) Lab 3 is a dry lab to give the students and opportunity to identify oxidation states of elements, the elements oxidized and reduced, and the oxidizing and reducing reactant. Reactions Page 15

16 Reactions Page 16

17 Overheads Reactions Page 17

18 Lesson 1 Definitions Double Displacement Reaction A reaction in which the cations of the reactants swap their anionic partners AB + CD AD + CB Single Displacement Reaction A reaction in which an element replaces the cation of an ionic compound A + BY AY + B Synthesis Reaction A reaction in which two or more reactants combine to form a single product A + B AB Decomposition Reaction A reaction in which a single reactant separates to form two or more products AB A + B Reactions Page 18

19 Lesson 2 Definitions Precipitation Reaction a reaction that produces a solid product Precipitate solid product produced by a precipitation reaction Reactions Page 19

20 Lesson 3 Definitions Acid / Base Neutralization Reaction reaction between an acid reactant and a base reactant that produces water as one of the products Functional Groups an atom (or group of atoms and their bonds) that impart specific chemical and physical properties to a molecule Esters Compounds that form between the alcohol function group of one reactant and the carboxylic acid functional group of another reactant Amide Compound that forms between the amine functional group of a reactant and the carboxylic acid functional group of the same reactant (in the case of amino acids) or a second reactant Reactions Page 20

21 Lesson 4 Definitions Oxidation-Reduction (Redox) Reaction a reaction that involves a transfer of electrons Element Oxidized the element that loses electrons to become more positive Element Reduced the element that gains electrons to become more negative Oxidizing Reactant reactant that causes an element to be oxidized (contains the element reduced) Reducing Reactant reactant that causes an element to be reduced (contains the element oxidized) Combustion The reaction of a hydrocarbon with oxygen to typically produce carbon dioxide and water Hydrocarbon A substance primarily composed of carbon and hydrogen Catalyst a substance that speeds up a reaction but does not undergo a permanent change Reactions Page 21

22 Reactions Page 22

23 CoCl 2 (aq) + 2 NaOH (aq) Co(OH) 2 (s) + 2 NaCl (aq) Cu (s) + 2 AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2 Ag (s) K 2 Cr 2 O 7 (aq) + Pb(NO 3 ) 2 (aq) 2 KNO 3 (aq) + PbCr 2 O 7 (s) The compound will be If it contains Unless combined with Soluble (aq) + Group 1, NH Soluble (aq) NO - 3, C 2 H 3 O - 2, ClO - - 4, HCO Soluble (aq) Halides (F -, Cl -, Br -, I - ) Ag +, Pb 2+ 2+, Hg 2 Soluble (aq) 2- SO 4 Ag +, Pb 2+, Hg 2+ 2, Ca 2+, Sr 2+, Ba 2+ Insoluble (s) O 2-, OH - Ca 2+, Sr 2+, Ba 2+ Insoluble (s) All other anions Reactions Page 23

24 Reactions Page 24

25 Carboxylic Acid Alcohol Ester Amine Amide Amino Acid Reactions Page 25

26 Cu (s) + 2 AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + 2 Ag (s) Cu (s) + 2 Ag + (aq) Cu 2+ (aq) + 2 Ag (s) Cu (s) + 2 Ag + (aq) Cu 2+ (aq) + 2 Ag (s) Reactions Page 26

27 2 C 8 H 18 (g) + 25 O 2 (g) 16 CO 2 (g) + 18 H 2 O (g) Reducing reactant oxidizing reactant C oxidized O reduced 3 C 12 H 22 O 11 (aq) + 3 O 2 (g) 11 C 2 H 5 OH (aq) + 14 CO 2 (g) Reactions Page 27

28 Reactions Page 28

29 Laboratories Reactions Page 29

30 Reactions Page 30

31 Laboratory # 1 Preparation (per 50 groups) 0.1 M Copper Sulfate Pentahydrate Dissolve g of copper sulfate pentahydrate in enough water to make 600 ml of solution. 0.1 M sodium carbonate Dissolve 0.42 g of sodium carbonate in enough water to make 50 ml of solution 0.1 M calcium chloride Dissolve 0.55 g of calcium chloride in enough water to make 50 ml of solution 0.1 M hydrochloric acid Slowly combine 4.2 ml of concentrated sulfuric acid in enough water to make 500 ml of solution Materials per group 5 test tubes Test tube rack 5 droppers 0.1 M copper sulfate pentahydrate 0.1 M sodium carbonate 0.1 M calcium carbonate 0.1 M hydrochloric acid Magnesium strips Steel wool 0.1 M potassium ferrocyanide Solid copper sulfate pentahydrate Test tube clamp Bunsen burner Lighter Straw Beaker ph meter Reactions Page 31

32 Procedures: Experiment 1 1. Add 20 drops of 0.1 M copper sulfate pentahydrate to a clean test tube. 2. Add 20 drops of 0.1 M sodium carbonate to the test tube. 3. Record your observations and answer the questions. Experiment 2 1. Add 5 ml of 0.1 M hydrochloric acid to a test tube. 2. Test the ph of the solution. 3. Add 0.4 g of magnesium to the test tube. 4. Allow the reaction to go to completion. 5. Test the ph of the solution. 6. Record your observations and answer the questions. Experiment 3 1. Place an eraser full of solid copper sulfate pentahydrate in the bottom of a test tube. 2. Using the test tube clamps hold the bottom of the test tube over a Bunsen burner flame. 3. Heat for 30 seconds to a minute. 4. Record your observations. (solid and rim of test tube) 5. Add a few drops of water to the test tube 6. Record your observations and answer the questions. Experiment 4 1. Add 20 drops of copper sulfate pentahydrate to a clean test tube. 2. Add 20 drops of calcium chloride to the test tube. 3. Record your observations and answer the questions. Experiment 5 1. Place a small piece of steel wool in the bottom of a test tube. 2. Cover the steel wool with 0.1 M copper sulfate pentahydrate. 3. Let the reaction sit for 10 minutes. 4. Record your observations. 5. Add 2 drops of 0.1 M potassium ferrocyanide. 6. Record your observations and answer the questions. Experiment 6 1. Place water in a beaker. 2. Test the ph and record. 3. Blow bubbles for 1 minute into the water using a straw. 4. Test the ph and record. 5. Answer the questions. Reactions Page 32

33 Data and Conclusions Experiment 1 What does the copper sulfate pentahydrate solution look like? What does the sodium carbonate solution look like? What did you observe when the copper sulfate pentahydrate combine with the sodium carbonate? Determine the state of matter for the reactants and the products in the reaction: CuSO 4 ( ) + Na 2 CO 3 ( ) CuCO 3 ( ) + Na 2 CO 3 ( ) Circle the reaction type represented. Single Displacement Double Displacement Synthesis Decomposition Experiment 2 What does the hydrochloric acid solution look like? The initial ph of solution was. What does the magnesium look like? What did you observe when the hydrochloric acid combined with the magnesium? The final ph of the solution was. Reactions Page 33

34 Did the ph increase or decrease as the reaction proceeded? The reaction studied was: Mg (s) + 2 HCl (aq) MgCl 2 (aq) + H 2 (g) Circle the reaction type represented. Single Displacement Double Displacement Synthesis Decomposition Explain why the ph increased or decreased given the reaction that occurred. Experiment 3 What does the solid copper sulfate pentahydrate look like at the start of the reaction? What does the solid look like after heating? What did you observe around the rim of the test tube? What does the solid look like after water was added to the test tube? The reaction studied was: CuSO. 4 5H 2 O (s) CuSO 4 (s) + 5 H 2 O (l) Circle the reaction type represented. Single Displacement Double Displacement Synthesis Decomposition Reactions Page 34

35 Experiment 4 What does the copper sulfate pentahydrate solution look like? What does the calcium chloride solution look like? What did you observe when the copper sulfate pentahydrate combine with the calcium chloride? Determine the state of matter for the reactants and the products in the reaction: CuSO 4 ( ) + CaCl 2 ( ) CuCl 2 ( ) + CaSO 4 ( ) Circle the reaction type represented. Single Displacement Double Displacement Synthesis Decomposition Experiment 5 What does the copper sulfate pentahydrate solution look like? What does the steel wool look like? What did you observe when the copper sulfate pentahydrate combined with the steel wool? What did you observe when the potassium ferrocyanide was added? If you were told that potassium ferrocyanide reacts with iron ion, what would you say was present in solution in the end? Reactions Page 35

36 The reaction studied was: Fe (s) + CuSO 4 (aq) FeSO 4 (aq) + Cu (s) Circle the reaction type represented. Single Displacement Double Displacement Synthesis Decomposition Experiment 6 The ph of the water at the start of the experiment was. The ph after air was bubbled through the water was. What would need to be present to cause the change in ph observed? The reaction studied was: H 2 O (l) + CO 2 (g) H 2 CO 4 (aq) Circle the reaction type represented. Single Displacement Double Displacement Synthesis Decomposition Reactions Page 36

37 Laboratory #2 Materials Needed (per group) 2 test tubes Test tube rack 4 droppers Test tube clamp Thermometer 250-mL beaker Hot plate Concentrated sulfuric acid Glacial Acetic acid Isoamyl alcohol 99% Ethyl alcohol Procedure 1. Obtain two test tubes and a test tube rack. Label the test tubes 1 and Prepare a warm water bath by filling a 250 ml beaker, heating the water to C. 3. While the water is heating, use clean droppers to add the proper amounts of alcohol and acid to the specified test tubes (refer to Table 1.1). Make sure to use clean a clean dropper for each liquid. After adding the alcohol and acid, swirl the test tubes around to mix the solutions. 4. Using a new dropper, add 5 drops of concentrated Sulfuric Acid to each test tube. Mix each solution. Caution: Concentrated sulfuric acid is toxic and may cause severe burns. If exposed to the acid, immediately wash the exposed area for several minutes, and notify your teacher. 5. Place both test tubes in the hot water bath for 10 minutes. After 10 minutes, remove the test tubes carefully with a test tube holder and place them on the test tube rack. Let them cool to room temperature before handling. 6. After the test tubes have cooled, carefully smell the ester by wafting (your teacher will demonstrate the proper method for smelling chemicals). Record your observations. Table 1.1 Test Tube Alcohol Acid 1 10 drops of Ethyl Alcohol 10 drops of Acetic Acid 2 20 drops of Isoamyl Alcohol 10 drops of Acetic Acid Reactions Page 37

38 Test tube 1 Ethyl alcohol and acetic acid Data and Conclusions What did you observe when you wafted the product? Complete the reaction below. C H 3 OH + C H 3 O OH Ethanol Acetic Acid Test tube 2 Isoamyl alcohol and acetic acid What did you observe when you wafted the product? Complete the reaction below. CH 3 H 3 C C OH + H 3 O OH Isoamyl Alcohol Acetic Acid Reactions Page 38

39 Laboratory #3 Ca (s) + 2H 2 O (l) Ca(OH) 2 (aq) + H 2 (g) Oxidation state of Ca in Ca Element Oxidized Oxidation state of H in H 2 O is a +1. Element Reduced Oxidation state of Ca in Ca(OH) 2 Oxidizing Reactant Oxidation state of H in H 2 Reducing Reactant Zn (s) + 2HCl (aq) ZnCl 2 (aq) + H 2 (g) Oxidation state of Zn in Zn Element Oxidized Oxidation state of H in HCl is a +1. Element Reduced Oxidation state of Zn in ZnCl 2 Oxidizing Reactant Oxidation state of H in H 2 Reducing Reactant CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O (l) Element Oxidized Element Reduced Oxidizing Reactant Reducing Reactant Reactions Page 39

40 2Al ( s ) + Fe 2 O 3 ( s ) Al 2 O 3 ( s ) + 2Fe ( l ) Oxidation state of Al in Al Element Oxidized Oxidation state of Fe in Fe 2 O 3 Element Reduced Oxidation state of Al in Al 2 O 3 Oxidizing Reactant Oxidation state of Fe in Fe Reducing Reactant C 10 H 8 (g) + 12 O 2 (g) 10 CO 2 (g) + 4 H 2 O (g) Element Oxidized Element Reduced Oxidizing Reactant Reducing Reactant Reactions Page 40