Introduction
Introduction
This WebQuest is all about chemical reactions. To pique your interest, please view the two videos below showing some very exothermic chemical reactions.
Welcome
We live in a world where chemical reactions are all around us. If you leave a bicycle outside in the rain you might see it begin to rust. When you bake a loaf of bread, chemical reactions are occurring. This WebQuest will help you in learning how to identify different chemical reactions, and discuss the energy associated with chemical reactions.
By the end of this WebQuest, you should be able to:
1. Balance chemical reactions
2. Identify different types of chemical reactions
3. Define and identify endothermic and exothermic reactions
NGSS Standards
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HS-PS1-2 Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties. HS-PS1-4
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You will accomplish these tasks by watching videos, completing online simulations, and practice problems to solidify your understanding of chemical reactions. This process will be valuable as it will help you explain many of the phenomena that occur around you each day!
Task
Evaluation Rubric
| Learning Target | Distinguished | Proficient | Unsatisfactory |
| Balance simple/complex chemical reactions | Can balance all chemical reactions including combustion reactions. | Can balance all chemical reactions excluding combustion reactions. | Mistakes are made with simple balancing problems. |
| Identify endothermic and exothermic reactions | Both endothermic and exothermic reactions are identified correctly | Some (1-2) reactions are identified incorrectly. | More than 2 reactions are identified incorrectly |
| Explain the difference between endothermic and exothermic rxns | Can explain verbally and graphically the difference endothermic and exothermic reactions. | Can only verbally distinguish between endothermic and exothermic reactions. | Cannot verbally nor graphically distinguish between endothermic and exothermic reactions. |
| Identify various chemical reactions | Can identify all 5 types of chemical reactions correctly. | Can identify 3-4 types of chemical reactions correctly. | Can identify 2 or fewer types of chemical reactions correctly. |
| Explanation of the reactions between silver nitrate and copper | Can explain at the particle level the exchange that occurs during this reaction. | Can explain at the macroscopic level what occurs during this reaction. | Did not complete the lab. |
Guided Questions/Learning Targets
1. I can balance simple and complex chemical reactions
2. I can identify endothermic and exothermic reactions
3. I can explain the difference in terms of energy of an endothermic and exothermic reaction
4. I can identify the five major types of chemical reactions
5. I can explain at the particle level the reaction between aqueous silver nitrate and solid copper
Task
Throughout this WebQuest you will complete the following task to accomplish the learning targets described above:
1. Watch videos and take notes on identifying and balancing equations.
2. Complete a group activity and act out a high school dance.
3. Work on online simulations to help differentiate between endothermic and exothermic reactions.
4. Complete an in-class lab that examines the reaction between aqueous silver nitrate and solid copper.
Process
Process and Resources
Watch the following videos:
The videos below will provide you information regarding how to identify different types of chemical reactions, how to balance chemical reactions, and the difference between endothermic vs. exothermic reactions. Complete the notes sheets below as you progress through the videos.
Types of Reactions
- What are the five different types of reactions?
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- What is always true about a combustion reaction? ________________________
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- What occurs in a synthesis reaction? ____________________________________
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- What occurs in a decomposition reaction? _______________________________
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- What occurs in a single replacement reaction? ___________________________
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- What occurs in a double replacement reaction? __________________________
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- Give a general equation for each kind of reaction:
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rxn type |
general equation |
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Steps to Identify the Type of Reaction
1) Does the reaction have oxygen as one of it's reactants and carbon dioxide and water as products? If yes, then it's a combustion reaction.
2) Does the reaction have two (or more) chemicals combining to form a new chemical? If yes, then it's a synthesis reaction.
3) Does the reaction have one large molecule falling apart into several small ones? If yes, then it's a decomposition reaction.
4. Does the reaction have any molecules that contain only one element? If yes, then it's a single replacement reaction.
5. If you haven't answered yes to any of the previous questions, then it's a double replacement reaction.
Balancing –Chem Notes Sheet
- In the reaction below, label
a.Reactants b. Products c. A subscript
F2 + Ca --> CaF2
- Draw an atomic level picture of the reaction F2 + Ca --> CaF2
- Is an equation balanced if not all of the reactant atoms form products? Explain.
- Is the equation CH4 + O2 -‐-‐> CO2 + H2O balanced? Explain.
- To balance an equation, do you change the subscripts or coefficients?
- Balance the equation and then label a coefficient:
___CH4 + ___O2 -‐-‐> ___CO2 + ____H2O
- Draw an atomic level picture of the balanced equation in #5 above.
- How does a balanced equation relate to the Law of Conservation of Matter?
- Describe the differences between endothermic and exothermic.
- The reaction between ammonium chloride and barium hydroxide is endothermic. Write the balanced chemical equation for this reaction.
Endothermic vs Exothermic Reactions Graphing
Use the simulation below to distinguish the difference between endothermic and exothermic reactions graphically.
https://phet.colorado.edu/en/simulation/legacy/reactions-and-rates
Class Activity
As a class we will act out the drama of the scenario set up in the POGIL below. This activity will simulate synthesis, decomposition, single replacement, and double replacement by relating these reactions to students at a high school dance. *Note: This can be completed individually and online; however, it is more fun and meaningful to complete in groups.
Shall We Dance? – Classifying Types of Chemical Reactions
Why?
Chemical reactions can be classified into different categories. Four common types are synthesis, decomposition, single replacement and double replacement.
Specific reactions corresponding to these general types are associated with health issues, environmental problems, and manufacturing processes. In order to use chemical reactions or evaluate their effects, you need to be able to identify the type of reaction.
Success Criteria
- Identify and differentiate between four types of chemical reactions: synthesis, decomposition, single replacement and double replacement.
Prerequisites
- Balancing equations
Types of Chemical Reactions:
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- Synthesis- Elements or less complex compounds come together to form a single more complex compound
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- Decomposition- A compound breaks apart into either elements or less complex compounds
- Single replacement- A single element replaces another one in a compound
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- Double replacement- Ions in a compound switch places with ions in another compound to form two new compounds
Model 1: Analogy - Dancing with Reactants
When you are thinking about the four different types of reactions I'd like you to think about its similarity to dancing (yes, dancing). I'll show you what I mean.
The dance…
Adam and Barbara were both single. No one was talking about "Adam and Barbara" being together before the dance. They both go to the dance alone.
However, they meet at just the perfect time when a song they both adore is playing. They end up holding hands the entire dance. After that fateful meeting no one ever sees Adam without Barbara, they are forever referred to as "Adam and Barbara".
Key Questions
- Represent the drama of Adam and Barbara as a chemical equation? Use A to represent Adam and B to represent Barbara.
- If A and B represent elements can you describe what is happening?
- How would you classify A and B using the words from the New Concepts section on the first page of this activity?
The dance continues…
Later that same evening Xavier and Yasmine, who have been ‘the couple’ forever, have a heated quarrel and break up.
- Represent the drama of Xavier and Yasmine as a chemical equation? Use X to represent Xavier and Y to represent Yasmine.
- If X and Y represent elements can you describe what is happening?
- How would you classify X and Y using the words from the New Concepts section on the first page of this activity?
- What type of reaction is represented in the picture below? Write your own analogy for the reaction illustrated in the picture.
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http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/sciber/chemtype.htm
- Write a chemical reaction for this scenario.
The dance continues…
In their blissful state, Adam and Barbara (AB) try to help Xavier and Yasmine (XY) reconcile their differences. After everyone agrees to stop quarreling, Adam asks Yasmine to dance. Xavier and Barbara decided that they will dance together as well.
- Represent Adam and Barbara’s attempt to reconcile Xavier and Yasmine’s differences as a chemical equation.
- How would you summarize this reaction?
- What type of reaction does this scenario represent? (Based on the New Concepts words)
Model 2: Types of Reactions
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Classification (Type) of Reaction |
Example: Using Symbols |
Example Reactions |
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Synthesis |
A + B € AB |
2H2 (g) + O2 (g) € 2H2O(l) |
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Decomposition |
XY € X + Y |
2H2O (l) € 2H2 (g) + O2 (g) |
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Single Replacement |
A + BC € AC + B |
2Al(s) + 3Cu(NO3)2 (aq) € 2Al(NO3)3(aq) + 3Cu(s) |
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Double Replacement |
AC + DE € AE + DC |
Pb(NO3)2 (aq)+ 2KI(aq)€PbI2(s) + 2KNO3 (aq) |
Key Questions
aq = aqueous, g = gas, s = solid, l = liquid
- As shown in the model, list the number of reactants and the number of products found in the synthesis reaction?
- As shown in the model, list the number of reactants and the number of products found in a decomposition reaction?
- How would you compare a single replacement reaction to a double replacement reaction?
Exercise
- Identify the type of reaction shown in each of the following chemical equations:
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KClO3(s) ---> 2KCl(s) + 3O2(g)
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- AgNO3(aq) + KCl(aq) --> AgCl(s) + KNO3(aq)
c. 2 H2(g) + O2(g) --> 2 H2O(g)
- 2 AgNO3(aq) + Cu(s) --> Cu(NO3)2(aq) + 2 Ag(s)
- CaCO3(s) --> CaO(s) + CO2(g)
- NaI(aq) + Cl2(g) --> 2NaCl(aq) + I2(s)
Problems
- For the reaction between zinc metal and hydrochloric acid (aqueous) producing zinc chloride (aqueous) and hydrogen gas
- write an equation for this reaction
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- balance the equation from Part a
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- classify the reaction
- For the reaction between aqueous calcium nitrate and aqueous sodium hydroxide producing the precipitate (solid) calcium hydroxide and aqueous sodium nitrate
- write an equation for this reaction
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- balance the equation from Part a
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- classify the reaction
- Nitrogen molecules and hydrogen molecules react to form ammonia gas.
- write an equation for this reaction
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- balance the equation from Part a
- classify the reaction and explain how you came to this conclusion
Silver Nitrate and Copper Lab
You will complete the following lab during class. See lab details below. *Note: Despite this being a WebQuest, as it is teaching chemical reactions a "wet" lab is included. Students must actually view chemical reactions to have these concepts become more realistic.
Chem Lab 5.2: The Mole Relationships of Chemical Reactions
Introduction
In this experiment, you will immerse a copper coil in a solution of silver nitrate and two new substances will be produced. Our mission is to determine the stoichiometry of the reaction between copper and silver nitrate. Before you begin the lab, write an equation for this reaction. What information about the products is missing?
Procedure
Day One
1) Obtain about 30 cm of Cu wire and polish it with steel wool if it is tarnished.
2) Coil the wire around a large test tube or two of your fingers, leaving the top 1/3 straight. Remove the test tube. Determine the mass of the Cu coil.
3) Obtain a clean, dry 250 ml beaker. Label the beaker with your initials and determine its mass.
4) Obtain about 2 g of silver nitrate.
5) Fill the clean beaker about 2/3 full with distilled water, add the silver nitrate crystals and stir carefully with a clean, rinsed stirring rod.
Caution: Silver nitrate may leave brown stains on the skin upon exposure to sunlight. The stain is harmless and will wear off in several days.
6) Bend the tip of the copper wire so it can hang into your solution in the beaker. Place the coil in the solution and observe/record any changes that occur.
Leave the beaker overnight.
Day Two
1) Very carefully bring your beaker to the lab table top. Record all your "day 2" observations.
2) Shake the crystals off the coil, lift the coil out of the solution, and, using a stirring rod if necessary, gently scrape any clinging silver into the solution. Rinse the coil with distilled water into the beaker.
3) Immerse the coil in a beaker of acetone provided by your teacher, swirl it several times, and then set the coil aside on paper towel to dry. After 5 minutes, determine the final mass of the Cu coil.
4) Let the crystals settle in the beaker, and decant the solution into the sink, leaving the silver crystals in the bottom.
5) Add 10 ml of 0.1 M silver nitrate solution to the beaker and gently swirl the mixture for several minutes. Allow the mixture to settle for several minutes and decant the solution on top into the sink.
6) Repeat step 5 with 3 separate rinsings of 10 ml of distilled water, allowing the mixture to settle between each rinsing.
7) Place the crystals in a drying oven and allow to dry overnight.
Day Three
1) Collect your beaker containing the dry silver from the drying oven.
2) Record the mass of the beaker and dried silver. Scrape the dry silver into a beaker provided by your teacher. Clean up your materials.
Data
- Construct a data table for the measurements you took in this experiment.
- Construct an organized method for recording your observations for each day.
Calculations (1-3 to be completed before discussion. 4-5 will be discussed in class.)
1) For the copper and silver nitrate, calculate the mass and the number of moles that were used in this reaction.
2) For the silver, calculate the mass and number of moles that was produced in this reaction.
3) Find the following ratios:
a) The ratio of moles of Copper reacted to moles of silver nitrate reacted.
b) The ratio of moles of silver nitrate reacted to moles of silver produced.
c) The ratio of moles of copper reacted to moles of silver produced.
4) Based on your answer to question #3, fill in the following blanks:
a) For every one mole of copper that reacts, ____ moles of silver nitrate react.
b) For every one mole of silver nitrate that reacts, ___ moles of silver are produced.
c) For every one mole of copper that reacts, ___ moles of silver are produced.
5) Write the above answers in the form of a balanced chemical equation. To do this you will need to predict the formula of the final product. Explain your logic in predicting the second product.
6) Based on the initial quantities of reactants and balanced equation, calculate the theoretical yield of silver.
7) Calculate the percent yield of silver.
Questions
1) From your observations, what evidence do you have that a chemical reaction occurred when the copper was placed in the silver nitrate?
2) What evidence do you have that the reaction required time to be completed?
3) Based on the observations of the copper wire, what evidence do you have that some of the copper reacted? Does this contradict the Law of Conservation of Mass?
4) Which ion (copper, silver or nitrate) caused the solution to become blue when the copper
and silver nitrate were put together in the beaker? Why? Give evidence from previous labs or experience.
5) In this experiment, which substance was the reagent in excess and which substance was the limiting reagent? Justify your answer using experimental observations.
6) Draw particle level diagrams of the chemical species in the beaker before, and then after the reaction.
7) We did not save the decanted solution, but what qualitative test could be done to test for the presence of unreacted silver nitrate solution?
8) Comment how each of the following might affect the mole ratio between moles of copper reacted to moles of silver produced. Specify whether or not the ratio would be erroneously too high, too low, or unaffected and why:
a) Using a very large piece of Cu wire
b) Using 1 gram of silver nitrate instead of 2-3 grams
c) Adding too much water when making the silver nitrate solution
d) Cleaning the Cu wire with steel wool after measuring the initial mass.
Evaluation
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General Evaluation
Lab Evaluation
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Conclusion
By completing this WebQuest you should be able to balance simple and complex chemical equations, identify and define endothermic and exothermic reactions, identify the five major types of chemicals reactions, and understand the reaction between aqueous silver nitrate and copper. Use the formative assessment below to reflect on your abilities (answers provided on the credits page).
Questions:
1) Balance the reaction below. Indicate the reaction type and if the reaction is endothermic or exothermic.
___CH4 + ___O2 --> ___CO2 + ___H2O + Energy
2) Balance the reaction below. Indicate the reaction type and if the reaction is endothermic or exothermic.
Energy + ___N2 + ___H2 --> ____NH3
3) When aqueous silver nitrate reacts with solid copper, indicate the products and what new solid is produced.
AgNO3 + Cu --> __________ + _____
What new solid is produced? __________
Credits
Questions (answer key):
1) Balance the reaction below. Indicate the reaction type and if the reaction is endothermic or exothermic.
CH4 + 2 O2 --> CO2 + 2 H2O + Energy
2) Balance the reaction below. Indicate the reaction type and if the reaction is endothermic or exothermic.
Energy + N2 + 3 H2 --> 2 NH3
3) When aqueous silver nitrate reacts with solid copper, indicate the products and what new solid is produced.
AgNO3 + Cu --> CuNO3 + Ag
What new solid is produced? Silver