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Balancing Act Chemical Reactions A WebQuest For La Mesa Prep By Judy Paul

Balancing Act Chemical Reactions A WebQuest For La Mesa Prep By Judy Paul. Introduction:.

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Balancing Act Chemical Reactions A WebQuest For La Mesa Prep By Judy Paul

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  1. Balancing ActChemical ReactionsA WebQuest For La Mesa Prep By Judy Paul

  2. Introduction: Have you ever baked a batch of cookies? Remember creaming the shortening with sugar; adding eggs, vanilla, baking soda, flour and spices to make cookie dough? You had all those reactants mixed in a bowl, but you still only had cookie dough. It took adding energy, in the form of a hot oven, to change teaspoonfuls of cookie dough into the desired product: cookies. Once the cookies had been baked, they were obviously not the individual reactants you started with like flour and eggs. You now had a totally different product - cookies! Could you change the cookies back into the original ingredients or had something totally new been produced? Was that tantalizing smell during the baking process a sign that chemical reactions were taking place? Assuming you did not sample the cookie dough, was all of it turned into cookies? What really happened in that oven? Take a cruise through this webquest for the “chemical” clues to all these questions - and even the grumbling in your tummy!

  3. Task: • With your partner you will review chemical reactions, formulas and equations; applying conservation of mass and basic mathematics to balance several equations. • Both of your will complete a worksheet on the topics mentioned above. • Together you will research, design (write-up) and demonstrate (on video) a simple lab showing a chemical reaction and the balanced equation associated with the reaction!

  4. Process: This “Process” will be lengthy and take several slides of this PowerPoint. To navigate through the Process, use the arrow(s) below on the right. To return to the top of this webquest, use the arrow in the top, left corner of each slide. • With your partner, start by downloading a copy (one for each of you) of the worksheet. Please remember to save the document to your student drive with a name you will remember! Then work through the key terms, questions and equations as you review the material. • To begin, review chemical reactions. What is happening in a chemical change and how is it different from a physical change? • Do you remember any of the signs that a chemical reaction/change has taken place? • What does a chemical equation represent? How is that different from a chemical formula? • How do you identify (describe/name) the molecules at the beginning and end of a chemical equation? What does the arrow(s) represent in the equation?

  5. Process continued: • Do you remember the “what goes in, must come out” philosophy of atoms in a chemical reaction? The means that atoms are neither created or destroyed in a chemical reaction. There is a proper way of expressing this law and it is the reason behind the idea of a balanced chemical equation. • In looking at chemical equations, it is VERY important that you know the difference between two items” subscripts and coefficients! REMEMBER: You can change coefficients when balancing an equation but you can’t change a subscript! WHY? • Now, before getting to the job of balancing equations, do you remember the three types of reactions covered in class? Please compare synthesis, decomposition and substitution (single/double replacement) reactions and give examples of each on your worksheet. • A chemical equation is not considered complete (balanced) unless it shows that all the reactant atoms entering the reaction are accounted for (the same number of each type of atom on each side of the equation: “=“) in the products. Balancing equations is easy once you learn the steps to follow (see worksheet!), learn to check your work and certainly - practice!

  6. Process continued: • Ok, now is the time to practice! Use your worksheet t-account tables to do the 5 equations at this site then check your work! • Now, spend some time with the balancing equations quiz brought to us by Jefferson Labs…. Begin at the beginner level and move up to intermediate (at least!) before moving on! Remember practice, practice and practice some more…… • We’ve covered types of reactions, how to recognize a reaction is occurring and the amount of matter in the reactions. Now let’s look at the reaction in terms of energy. What is meant by activation energy in a reaction and why is it analogous (like) pushing a boulder over a hill? • Define and diagram (energy diagram) an endothermic reaction and an exothermic reaction. • The best part: take a look at an endothermic reaction and describe what is happening and why! Now for an exothermic reaction - WOW! Be sure to write down your observations and explanations! (remember endo/inside - into and exo/outside - exit!).

  7. Process continued: • Have your teacher review your worksheets. • FINALLY - THE REALLY FUN PART!!!! • Download a copy of the lab report you and your partner will be completing. • Using the “Resources” section, choose a simple lab to do as the final part of your WQ. • Write up the lab for your teacher’s approval. • Practice the lab and prepare a video of the lab. • Complete the lab conclusions/write-up. • Update your eportfolios with your lab/video.

  8. Research sites: http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson81.htm http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/masscons.html http://members.aol.com/profchm/balance.html http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Meaning-of-Equation.html http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Equations.html Experiment sites: http://www.haverford.edu/educ/knight-booklet/mustitrust.htm http://www2.uni-siegen.de/~pci/versuche/english/v44-24-1.html http://chemistry.about.com/cs/howtos/ht/endothermic.htm http://scifun.chem.wisc.edu/HomeExpts/tarnish.html*** http://ncwsnc.cheminst.ca/experiments/eelectrowater.html ** http://www.emsb.qc.ca/laurenhill/science/electrolysis.pdf http://www.siraze.net/chemistry/sezennur/subjects/experiment/002.pdf http://www.familieswithpurpose.com/funwithgas.html*** Resources:

  9. Conclusion: Is your tummy still growling - or should we say preparing for that wonderful series of chemical reactions we call eating? As for the preparation part, would you agree that a good cook is probably unknowingly, a good chemist? Are you? FYI: There are many cooking websites out there that explore kitchen chemistry and are only a mouse click away for those of you interested in cuisine! Enjoy!

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