Chemical Reactions. Video 7 Combustion Reactions I can identify and predict the products of combustion

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1 Chemical Reactions Chemical Reactions: Chemical reactions play a significant role in our lives. Considering the abundance of substances around and in us, it isn t surprising that we observe numerous examples of chemical reactions in everyday life. A chemical reaction is defined as the process during which a set of chemical substances react with each other. This leads to their conversion into other substances. The initial substances are referred to as reactants and the ending substances formed from the reaction are referred to as products. In general, the chemical properties of the reactants and products are different from each other There are numerous products that each and every one of us uses on a daily basis that were formulated from the application of a specific chemical reaction. For example, the toothpaste you use to brush your teeth, the soaps and shampoos you use to cleanse yourself, and any cleaning agent used around the house are all results of chemical reactions. Additionally, from a biological standpoint, there are numerous reactions responsible for your existence. Cellular respiration and photosynthesis (yes we talked extensively about them in biology), the rusting of metal, and any process of cooking or baking are all examples of chemical reactions that you experience on a daily basis. Throughout the unit we will look at five types of reactions and why these reactions need to be balanced. We will look at reactions that affect your everyday life and well as reactions that are unique to chemistry and chemistry experiments. Type of Reaction Generic Formulas Combination/Synthesis A + B AB Decomposition AB A + B Single-Replacement A + BC AC + B Double-Replacement AB + CD AD + CB Combustion C x H y + O 2 CO 2 + H 2 O All the videos will be posted on YouTube and can be accessed using multiple sources. The videos have been formatted to work on iphones, ipads, Android phones, Kindles, and Nooks. The titles of the videos are listed below so that you can search them, and the creator of the videos should be NRHSChemistry. Lesson Target(s) for Each Video: Video 1 Writing Chemical Reactions I can construct a sentence describing a balanced chemical reaction. I can create a balanced chemical reaction from a sentence describing the reaction. Video 2 Combination Reactions I can identify and predict the products of combination reactions. Video 3 Special Case Combination Reactions I can identify and predict the products of special case combination reactions. Video 4 Decomposition Reactions I can identify and predict the products of decomposition reactions. Video 5 Single-Replacement Reactions I can identify and predict the products of singlereplacement reactions. I can apply the activity series when predicting the products of single-replacement reactions. Video 6 Double-Replacement Reactions I can identify and predict the products of doublereplacement reactions. Video 7 Combustion Reactions I can identify and predict the products of combustion reactions. Video 8 Balancing Reactions I can prove the conservation of mass through a balanced chemical reaction. I can produce properly written and balanced chemical reactions. Essential Learning Outcomes: 1. Chemical formulas will give clues to the type of chemical reaction and the ways that a chemical will react. 2. Changes can occur within a substance that alter its identity.

2 Required activities: Due dates are in parentheses Chemical Reactions P.S. 1-4 (12/21) o Video 1 Writing Chemical Rxns (12/14) Chemical Reactions P.S (1/2) o Video 2 Combination Reactions (12/19) o Video 3 Special Case Rxns (12/19) o Video 4 Decomposition Reactions (12/20) o Video 5 Single-Replacement Rxns (12/21) Chemical Reactions P.S (1/4) o Video 6 Double-Replacement Rxns (12/21) o Video 7 Combustion Reactions (1/2) Chemical Reactions P.S (1/9) o Video 8 Balancing Reactions (1/4) Balancing Reactions Worksheet (1/6) Writing and Balancing Worksheet (1/6) Predicting Products Worksheets (1/9) Reaction Rate Lab (12/19 to 1/2) o Peer Review of Report (1/3) o Lab Report (1/6) Chemical Reactions Unit Quest (1/10) Activity series Balanced equation Catalyst Important Vocabulary Chemical equation Coefficients Combination reaction Combustion reaction Combustion reaction Decomposition reaction Double-replacement reaction Single-replacement reaction Additional Resources: 1) Types of Reactions 2) Balancing Reactions 3) Balancing Reactions Practice Problem Websites: 1) 2) iphone and ipad apps: There are none that I could find.if you find one and feel it is useful, please let me know!!!

3 Chemistry Name: Problems and Questions Chemical Reactions Hour: Directions: Answer the following questions using complete sentences when necessary. Correct naming and writing of formulas will be required for credit. On numerical problems, show all work, circle your answers, and follow all rules of significant figures for full credit. 1. Write the formulas and other symbols for these substances. a) Metallic potassium b) Sodium chloride dissolved in water c) Heat supplied to a chemical reaction d) Liquid mercury e) Zinc chloride as a catalyst f) Carbon dioxide gas 2. What is the purpose of a catalyst? 3. Write a sentence that describes each chemical reaction. a) 2K (s) + 2H 2O (l) 2KOH (aq) + H 2(g) b) NaOH (aq) + HNO 3(aq) H 2O (l) + NaNO 3(aq) c) FeO (s) + C (s) Fe (s) + CO (g) d) Pb(NO 3) 2(aq) + NaOH (aq) Pb(OH) 2(s) + NaNO 3(aq) 4. Write the complete chemical reaction and symbols of each of the following: a) Aqueous magnesium bromide and chlorine gas yield aqueous magnesium chloride and bromine gas when the reaction is heated. b) Sodium metal and water yield aqueous sodium hydroxide and hydrogen gas. c) Solid potassium nitrate decomposes into solid potassium nitrite and oxygen gas with the presence of the catalyst MnO 2. d) Solid calcium oxide and aqueous hydrochloric acid gives aqueous calcium chloride and liquid water. 5. What is a characteristic of every combination reaction? 6. Write the complete reactions and formulas then name the product in each of these combination reactions. The reactants are given below. a) Sodium metal and bromine liquid b) Magnesium metal and nitrogen gas with a platinum catalyst c) Sulfur dioxide gas and water d) Beryllium metal and fluorine gas 7. What is a characteristic of every decomposition reaction? 8. Write the complete chemical reaction including the other product of the following decomposition reactions underline the other product. a) Hydrogen peroxide yields water and. b) Magnesium chlorate yields magnesium chloride and. c) Hydrogen iodide yields two products, write the reaction. d) Sodium nitrate yields sodium nitrite and. e) Dinitrogen pentoxide yields two products, write the reaction. 9. Based on the activity series of metals and halogens, which element within each pair is more likely to replace the other in a compound? a) K and Na e) Au and Ag b) Al and Ni f) Cl 2 and I 2 c) Bi and Cr g) Fe and Sr d) Cl 2 and F 2 h) I 2 and F Write the complete reaction of the following single replacement reactions. If a reaction does not occur put "no reaction" in place of the products. Remember water can be written as HOH rather than H 2O. The product formulas must be written for credit. a) Aluminum + copper (II) nitrate e) Copper and magnesium nitrite b) Calcium and water f) Chlorine and potassium iodide c) Zinc + lead (II) nitrate g) Fluorine gas and calcium bromide d) Barium + silver sulfate h) Iodine liquid and copper (II) chloride 11. Will all metals replace H in H 2O? Explain using the activity series. 12. Use the named chemicals below to write four double replacement reactions and their products. All formulas must be used in writing the reactions. 1) Hydrogen sulfate (sulfuric acid) 4) Aluminum hydroxide 2) Potassium chromate 5) Ammonium carbonate 3) Strontium bromide

4 13. Write the complete reaction formula of the entire reaction (reactants and products). Assume that the reaction does react to form products. Example: Lead (II) nitrate and sodium iodide Answer: Pb(NO 3) 2 + NaI NaNO 3 + PbI 2 a) Hydrogen sulfate (sulfuric acid) and magnesium hydroxide b) Hydrogen sulfide and zinc chloride c) Silver nitrate and ammonium acetate d) Sodium nitrate and copper (I) acetate e) Iron (III) chromate and lithium hydroxide f) Barium chloride and hydrogen phosphate (phosphoric acid) 14. What are the "driving forces" in a double replacement reaction? 15. Write the equations for the complete combustion of each of these compounds. a) Acetic acid, HC 2H 3O 2 b) Decane, C 10H 22 c) Glycerol, C 3H 8O 3 d) Sucrose, C 12H 22O Write the formulas of these reactions then balance them. Example:Sodium metal and water yields sodium hydroxide and hydrogen gas. Answer: 2Na (s) + 2H 2O 2NaOH + H 2(g) a) Iron (II) nitrate and sodium chromate yield sodium nitrate and iron (II) chromate b) Manganese (IV) oxide and hydrogen chloride yield manganese (II) chloride and water and chlorine gas. c) Complete combustion of C 3H 6. d) Barium chlorate yields barium chloride and oxygen gas. e) Zinc hydroxide and hydrogen phosphate yield zinc phosphate and water. f) Carbon monoxide and iron (III) oxide yield iron and carbon dioxide. g) Carbon disulfide and chlorine gas yield carbon tetrachloride and disulfur dichloride h) CH 4 and Br 2 CH 3Br + HBr i) Barium cyanide and hydrogen sulfate yield barium sulfate and hydrogen cyanide. j) Ammonium dichromate yields chromium (III) oxide and water and nitrogen gas. 17. Balance the reactions in problem number 15. Re-write the reactions before balancing them. 18. Balance each of these equations. Identify each as to type. a) HCl + Fe 2O 3 FeCl 3 + H 2O f) C 6H 5OH + O 2 CO 2 + H 2O b) Li + O 2 Li 2O g) KClO 4 KCl + O 2 c) MgCO 3 MgO + CO 2 h) AgNO 3 + H 2S Ag 2S + HNO 3 d) HC 2H 3O 2 + Al(OH) 3 Al(C 2H 3O 2) 3 + H 2O i) Cl 2 +KI KCl +I 2 e) Fe 3O 4 + H 2 Fe + H 2O j) FeCl 3 + NaOH Fe(OH) 3 + NaCl 19. Each of these equations is "balanced" but incorrect. Find the errors and correctly balance each equation. a) Mg + H 2SO 4 Mg 2SO 4 + H 2 b) H 2 + Cl 2 H 2Cl 2 c) NH 3 N + H 3 d) Cl 2 + NaI NaCl 2 + I e) Na + O 2 NaO 2 f) MgCl + CaOH MgOH + CaCl 20. Write balanced chemical equations for these double-replacement reactions that occur in aqueous solution. a) Sodium hydroxide reacts with hydrogen nitrate. b) Solutions of potassium fluoride and calcium nitrate are mixed. c) Zinc sulfide is added to hydrogen sulfate (sulfuric acid). d) A solution of calcium iodide is poured into a solution of mercury (II) nitrate. 21. Write balanced chemical equations for each of these combination reactions. a) Dichlorine heptoxide + water b) Hydrogen + bromine c) Sodium oxide + water d) Aluminum + chlorine gas 22. Write balanced chemical equations for each of these single replacement reactions that take place in water solution. Then balance each equation. Write "no reaction" if no reaction occurs. a) A piece of silver jewelry is dropped in hydrochloric acid. b) Bromine reacts with aqueous barium iodide. c) A piece of steel wool (iron) is placed in sulfuric acid. d) Mercury is poured into an aqueous solution of zinc nitrate.

5 Predicting Products of Chemical Reactions: In each of the following examples: a. Identify the type of reaction b. Write the formulas for the reactants and products c. Balance the reaction 1. Aluminum metal plus hydrochloric acid 2. Calcium hydroxide plus nitric acid 3. Zinc chloride and hydrogen sulfide react 4. Sodium chloride decomposes 5. Barium nitrate plus sodium carbonate 6. Zinc carbonate undergoes decomposition 7. Potassium plus fluorine gas 8. Iron (III) hydroxide plus phosphoric acid 9. Sodium plus nitric acid 10. Copper (II) plus sulfuric acid 11. Lead (II) plus potassium chlorate

6 12. Oxygen plus sulfur 13. Sodium sulfate plus barium chloride 14. Mercury (II) plus nitric acid 15. Calcium carbonate plus lithium chloride 16. Sodium cyanide plus tin (IV) silicate 17. Magnesium plus hydrochloric acid 18. Mercury (II) oxide (heated) 19. Ammonium phosphate plus aluminum chloride 20. Calcium plus oxygen gas 21. Calcium plus phosphoric acid 22. Calcium chloride plus ammonium hydroxide

7 Balancing Chemical Reactions: Balance the following chemical reactions: 1. CH 4 + O 2 CO 2 + H 2 O 2. Na + Cl 2 NaCl 3. Al + O 2 Al 2 O 3 4. N 2 + H 2 NH 3 5. CO + H 2 C 8 H 18 + H 2 O 6. FeO 3 + CO Fe + CO 2 7. H 2 SO 4 + Pb(OH) 4 Pb(SO 4 ) 2 + H 2 O 8. Al + HCl AlCl 3 + H 2 9. Ca 3 (PO 4 ) 2 + H 2 SO 4 CaSO 4 + Ca(H 2 PO 4 ) H 3 PO 4 + HCl PCl 5 + H 2 O 11. Fe + H 2 SO 4 Fe 2 (SO 4 ) 3 + H C 2 H 6 + O 2 H 2 O + CO KOH + H 3 PO 4 K 3 PO 4 + H 2 O 14. SnO 2 + H 2 Sn + H 2 O 15. NH 3 + O 2 NO + H 2 O 16. KNO 3 + H 2 CO 3 K 2 CO 3 + HNO B 2 Br 6 + HNO 3 B(NO 3 ) 3 + HBr 18. BF 3 + Li 2 SO 3 B 2 (SO 3 ) 3 + LiF 19. (NH 4 ) 3 PO 4 + Pb(NO 3 ) 4 Pb 3 (PO 4 ) 4 + NH 4 NO SeCl 6 + O 2 SeO 2 + Cl SiCl 4 + H 2 O SiO 2 + HCl 22. As + NaOH Na 3 AsO 3 + H Au 2 S 3 + H 2 Au + H 2 S 24. V 2 O 5 + HCl VOCl 3 + H 2 O 25. Hg(OH) 2 + H 3 PO 4 Hg 3 (PO 4 ) 2 + H 2 O

8 Writing and Balancing Chemical Reactions Worksheet DIRECTIONS: For each problem, identify the type of reaction, and predict the products. Then balance the reaction. If there is no reaction, write no reaction and state the type of reaction. 1. H 2 + O 2 2. HgO 3. Zn + HCl 4. C 7 H 6 O 2 + O 2 5. Al(OH) 3 + H 2 SO 4 6. KClO 3 KCl + 7. FeO + H 2 8. Na + H 2 O 9. S 8 + Fe 10. CaO + H 2 O 11. FeCl 2 + NH 4 OH 12. Al + O H 2 O 2 H 2 O Ag + Na 2 SO Pb(NO 3 ) 2 + NaBr 16. C 5 H 12 + O SO 3 + H 2 O 18. NaCl 19. BBr 3 + F Ba(OH) 2 + HCl 21. Cu + AgNO CaCO 3 CaO Fe 2 O 3 + H K 2 SO 4 + BaCl Cu + O Mn 2 O Ca(OH) 2 + NH 4 Cl 28. H 3 PO 4 + NH 4 OH 29. Zn + H 2 SO CH 4 + O Na 2 O + H 2 O 32. H 2 S + KOH 33. Mg + N N 2 O C 12 H 26 + O 2 Type of Rxn.

9 Lab 21: Reaction Rates: Why Do Change in Temperature and Reactant Concentration Affect the Rate of Reaction? Introduction The molecular-kinetic theory of matter suggests that all matter is made up of subatomic particles called atoms that are constantly in motion. These atoms can be joined together to form molecules. Atoms have kinetic energy because they move and vibrate. The more kinetic energy an atom has, the fast it moves or vibrates. Temperature is a measurement of the average kinetic energy of all the atoms in a substance. The average kinetic energy of the particles within a substance increases and decreases as it changes temperature. Heat, in contrast, is the total kinetic energy of all the particles in a substance. A chemical reaction, as you have learned, is simply the rearrangement of atoms. The substances (elements and/or compounds) that are changed into other substances during a chemical reaction are called reactants. The substances that a produced as a result of a chemical reaction are called products. Chemical equations show the reactants and products of a chemical reaction. A chemical equation includes the chemical formulas of the reactants and the products. The products and reactants are separated by an arrow symbol ( ), and the chemical formula for each individual substance is separated by a plus sign (+). A balanced chemical reaction tells us the nature of the products and the amount of product that is formed from a given amount of reactants. A balanced chemical equation, however, tells us little about how long it takes for the reaction to happen. Some chemical reactions, such as the rusting of iron, happen slowly over time, while others, such as the burning of gasoline, are almost instantaneous. The speed of any reaction is indicated by its reaction rate, which is a measure of how quickly the reactants transform into products. As shown in Figure L21.1, a reaction begins with only reactant molecules. Over time, the reactant molecules interact with each other and form product molecules. The concentration of reactant molecules and the product molecules, as a result, will change during the process of a reaction. The rate of a reaction can therefore be calculated by measuring how the concentration of the reactants decreases of the concentration of the products increases as a function of time. The rate of a reaction can also be measured by timing how long it takes for a product to appear of for a reactant to disappear once the reaction begins. It is important for chemists to understand how and why different factors affect the rate of a chemical reaction so they can make a wide range of products in a safe and economical manner. You will therefore explore two factors that affect the rate of a specific reaction and then develop a conceptual model that you can use to explain your observations and predict the rate of this reaction under different conditions. FIGURE L21.1 A model of what happens during a chemical reaction over time Your Task Determine how temperature and changes in concentration of a reactant affect the rate of reaction between magnesium (Mg) nad hydrochloric acid (HCl). Then develop a conceptual model that can be used to exaplain why these factors influence raction rate. Once you have developed you model, you will need to determine if it is consistent with the rate of reaction that you observe under other conditions. The guiding question of this investigation is, Why do changes in temperature and reactant concentration affect the rate of reaction?

10 Materials You may use any of the following materials during your investigation: Consumables 2 pieces of 18 gauge copper wire (20 cm) Magnesium ribbon (30 cm) 3 M HCl 2 M HCl 1 M HCl 0.5 M HCl Ice Equipment 2 test tubes Test tube rack Graduated cylinder (10 ml) 2 beakers (250 ml) Thermometer (or temperature probe) Hot plate Electronic balance ph paper Safety Precautions Follow all normal lab safety rules. Magnesium is a flammable solid, and hydrochloric acid is a corrosive liquid. Your teacher will explain relevant and important information about working with the chemicals associated with this investigation. In addition, take the following safety precautions: Wear indirectly vented chemical-splash goggles Do not heat hydrochloric acid directly on a hot plate; rather, heat the hydrochloric acid using a hot bath and keep the temperature of the bath between 20 C and 60 C. Use caution when working with hot plates because they can burn skin. Hot plates also need to be kept away from water and other liquids. Handle all glassware with care. Wash your hands with soap and water before leaving the laboratory. Investigation Proposal Required? Yes No Getting Started The first step in developing your model is to design and carry out two experiments. The goal of the first experiment will be to determine how temperature affects reaction rate. The goal of the second experiment will be to determine how reactant concentration affects reaction rate. For these two experiments, you will focus on the reaction of magnesium and hydrochloric acid. These two chemicals react to form hydrogen gas and magnesium chloride. The equation for the reaction is: Mg (s) + 2HCl (aq) H 2(g) + MgCl 2(aq) You can measure the reaction rate by simply timing how long it takes for the solid magnesium to be no longer visible once it is mixed with the hydrochloric acid. You can also measure the reaction rate by timing how long hydrogen gas is produced after the magnesium and hydrochloric acid are mixed. The unit of measurement for a reaction rate is mol/sec it will therefore be important for you to determine how many moles of each reactant you used for each test. To design your two experiments, you will need to decide what type of data you need to collect, how you will collect the data, and how you will analyze the data. To determine what type of data you need to collect, think about the following questions: o How will you determine the number of moles of each reactant at the beginning of the reaction? o How will you know when the reaction starts and when it is finished? o What type of measurements will you need to record during each experiment? o When will you need to make these measurements or observations?

11 To determine how you will collect the data, think about the following questions: o How much magnesium ribbon will you use in each test? o How much hydrochloric acid will you need to use to submerge the magnesium ribbon? o How will you prevent the magnesium ribbon from floating to the top of the hydrochloric acid? One way to prevent magnesium from floating to the top on the hydrochloric acid is to use copper wire to create a cage (see Figure L21.2). o What will serve as your independent variable? o What types of comparisons will you need to make? o How will you hold other variables constant? o What will you do to reduce measurement error? FIGURE L21.2 o How will you keep track of the data you collect and how will you How to suspend magnesium (Mg) ribbon in the organize it? hydrochloric acid (HCl). The copper wire does To determine how you will analyze the data, think about the following not react with the HCl. questions: o What type of graph could you create to help make sense of your data? o What types of calculations will you need to make? Once you have carried out you two experiments, your group will need to develop a conceptual model. This conceptual model must provide an underlying reason for your findings about the effect of temperature and reactant concentration on reaction rate. Your model should also include an explanation of what is happening at the submicroscopic level between and within molecules during a reaction. The molecular-kinetic theory of matter should serve as the theoretical foundation of your model. The last step in this investigation is to test your model. To accomplish this goal, you can use the same reaction but test different temperatures and concentrations to determine if your model is consistent with the rates of reactions you observe under different conditions. If you can use your model to make accurate predictions about the rate of this reaction under different conditions, then you will be able to generate the evidence you need to convince others that the conceptual model you developed is valid. Connections to Crosscutting Concepts As you work through your investigation, be sure to think about the importance of developing casual explanations for observations, how models are used to help understand natural phenomena, the importance of imagination and creativity in science, and the role of experiments in science.

12 Initial Argument Once your group has finished collecting and analyzing your data, you will need to develop an initial argument. Your argument must include a claim, which is your answer to the guiding question. Your argument must also include evidence in support of your claim. The evidence is your analysis of the data and your interpretation of what the analysis means. Finally, you must include a justification of the evidence in your argument. You will therefore need to use a scientific concept or principle to explain why the evidence that you decided to use is relevant and important. You will create your initial argument on a whiteboard. Your whiteboard must include all the information shown in Figure L21.3. FIGURE L21.3 Argument presentation on a whiteboard Argumentation Session The argumentation session allows all of the groups to share their arguments. One member of each group stays at the lab station to share that group s argument, while the other members of the group go to the other lab stations one at a time to listen to and critique the arguments developed by their classmates. The goal of the argumentation session is not to convince others that your argument is the best one; rather, the goal is to identify errors or instances of faulty reasoning in the initial arguments so these mistakes can be fixed. You will therefore need to evaluate the content of the claim, the quality of the evidence used to support the claim, and the strength of the justification of the evidence included in each argument that you see. To critique an argument, you might need more information that what is included on the whiteboard. You might, therefore, need to ask the presenter one or more of the following questions, such as: How did your group collect the data? Why did you use that method? What did your group do to make sure the data you collected are reliable? What did you do to decrease measurement error? What did your group do to analyze the data, and why did you decide to do it that way? Did you check your calculations? Is that the only way to interpret the results of your group s analysis? How do you know that your interpretation of the analysis is appropriate? Why did your group decide to present your evidence in that manner? What other claims did your group discuss before deciding on that one? Why did you abandon those alternative ideas? How confident are you that your group s claim is valid? What could you do to increase your confidence? Once the argumentation session is complete, you will have a chance to meet with your group and revise your original argument. Your group might need to gather more data or design a way to test one or more alternative claims as part of this process. Remember, your goal at this stage of the investigation is to develop the most valid or acceptable answer to the research/guiding question! Report Once you have completed your research, you will need to prepare an investigation report that consists of three sections that provide answers to the following questions: 1. What question were you trying to answer and why? 2. What did you do during your investigation and why did you conduct your investigation in this way? 3. What is your argument? Your report should answer these questions in four pages or less. The report must be typed and any diagrams, figures, or tables should be embedded into the document. Be sure to write in a persuasive style; you are trying to convince others that your claim is acceptable and valid!

13 Day 1 Investigation Timeline Option E Stage 1: Identify the task and the guiding question. Hold a tool talk Small groups of students 50 Minutes Stage 2: Design a method and collect data Day 2 Groups then Finish Stage 2. Collect data 50 Minutes Groups then Day 3 Stage 3: Analyze data and develop a tentative argument Each group then shares its argument during an 50 Minutes Stage 4: Argumentation session If needed, groups can Collect additional data or reanalyze the collected data The teacher then leads an The teacher then leads an Stage 5: Explicit and reflective discussion Day 4 Individual students then Stage 6: Write and investigation 50 Minutes The report then goes through a Day 5 Stage 7: Double-blind group peer review Each student then 50 Minutes Stage 8: Revises and submits his or her report

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15 Investigation Proposal A The guiding question IF Hypothesis 1 Hypothesis 2 IF AND Procedure The Test What data will you collect? How will you analyze the data? What safety precautions will you follow? Predicted Result if hypothesis 1 is valid THEN Predicted result if hypothesis 2 is valid THEN AND The Actual Results I approve of this investigation. Instructor s Signature Date