CHEMICAL REACTION

Introduction

This WebQuest is all about chemical reactions.

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. 

By the end of this WebQuest, you should be able to:

1. Balance chemical reactions

2. Identify different types of chemical reactions

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 endothermic and exothermic reactions. Can balance all chemical reactions excluding endothermic and exothermic reactions. Mistakes are made with simple balancing problems.
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.

Process

Process and Resources

Step - 1

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. 

https://youtu.be/NId6o9rfSyk

Types of Reactions 

  1. What are the five different types of reactions?
  2. What is combination reaction?
  3. Give the reaction between quicklime and water.
  4. What is slaked lime?
  5. What occurs in a single displacement reaction?
  6. What occurs in a double displacement reaction?
  7. Give a general equation for each kind of reaction

    Reaction  type

    General equation

    1)

     

    2)

     

    3)

     

    4)

     

    5)

     

Step - 2

Steps to Identify the Type of Reaction

1) Does the reaction have only one product?  If yes, then it's a combination reaction.

2) Does the reaction have two or more products from a single reactant?  If yes, then it's a decomposition reaction.

3) Does the reaction have any color change ?  If yes, then it's a displacement reaction.

4. Does the reaction contain two ionic compounds? If yes, then it's a double displacement reaction.

5. If you haven't answered yes to any of the previous questions, then it's a redox reaction. 

https://youtu.be/NId6o9rfSyk

 

Balancing –Chem Notes Sheet

  1. Is the equation CH4 + O2 -­‐-­‐> CO2 + H2O balanced? Explain.
  2. To balance an equation, do you change the subscripts or coefficients?
  3. Balance the equation and then label a coefficient:

    ___CH4 + ___O2 -­‐-­‐> ___CO2 + ____H2O
  4. How does a balanced equation relate to the Law of Conservation of Matter?
  5. Describe the differences between endothermic and exothermic.
  6. The reaction between ammonium chloride and barium hydroxide is endothermic. Write the balanced chemical equation for this reaction.

Step - 3

Types of Reactions

Classification (Type) of Reaction

Example: Using Symbols

Example Reactions

Combination

A + B € AB

2H2 (g) + O2 (g) € 2H2O(l)

Decomposition

XY € X + Y

2H2O (l) € 2H2 (g) + O2 (g)

Single Displacement

A + BC € AC + B

2Al(s) + 3Cu(NO3)2 (aq) € 2Al(NO3)3(aq) +

3Cu(s)

Double

Displacement

AC + DE € AE + DC

Pb(NO3)2 (aq)+ 2KI(aq)€PbI2(s) + 2KNO3 (aq)

 

Key Questions

aq = aqueous, g = gas, s = solid, l = liquid

 

  1. As shown in the model, list the number of reactants and the number of products found in the combination reaction?

 

  1. As shown in the model, list the number of reactants and the number of products found in a decomposition reaction?

 

  1. How would you compare a single displacement reaction to a double displacement reaction?

Exercise

Identify the type of reaction shown in each of the following chemical equations:

  1. KClO3(s)     --->      2KCl(s) + 3O2(g)
  2. AgNO3(aq) + KCl(aq)      -->    AgCl(s) + KNO3(aq)
  3. 2 H2(g) + O2(g)      -->        2 H2O(g)
  4. 2 AgNO3(aq) + Cu(s)     -->     Cu(NO3)2(aq) + 2 Ag(s)
  5. CaCO3(s)      -->    CaO(s) + CO2(g)
  6. NaI(aq) +  Cl2(g)       -->          2NaCl(aq) + I2(s)

 

Problems

  1. For the reaction between zinc metal and hydrochloric acid (aqueous) producing zinc chloride (aqueous) and hydrogen gas
    1. write an equation for this reaction
    2. balance the equation from Part a
    3. classify the reaction
  2. For the reaction between aqueous calcium nitrate and aqueous sodium hydroxide producing the precipitate (solid) calcium hydroxide and aqueous sodium nitrate
    1. write an equation for this reaction
    2. balance the equation from Part a
    3. classify the reaction
  3. Nitrogen molecules and hydrogen molecules react to form ammonia gas.
    1. write an equation for this reaction
    2. balance the equation from Part a
    3. 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. Students must actually view chemical reactions to have these concepts become more realistic.

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 

  1. Construct a data table for the measurements you took in this experiment.
  2. 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.

 

 

 

 

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.  

Teacher Page

Hello, my name is Revathy R Nathan

I am a first year student at the Govt.College of Teacher Education, kerala who is pursuing his Post graduation in Education. I am very friendly and approachable person who is more than willing to help those in need in whatsoever way that I can as I believe that we should help each other during our times of need.I hope you enjoyed viewing this web quest Thanks again and may God's richest blessings be upon your life!