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LARN 165 C42D1

Your Goal:

Your goal today should be to begin to learn the SINGLE ATOM RATIO method of balancing chemical expressions using oxidation numbers is explained with step by step examples on the ActivInspire flipchart for Oxidation and Reduction.  Reading section 20.3 and studying the change in oxidation number method will also add to your understanding.  [Please do NOT spend time reading or studying what your text calls the half reaction method and what other texts call the ion-electron method.  Wherever the text asks you to do an example using that method use the single atom ratio method instead!!]  To learn use any using oxidation numbers you will need to be able to assign the quickly and accurately so start out by reviewing the four rules and six priorities for assigning oxidation numbers assigned in LARN 163, and LARN 164.  Then move on to assigning oxidation numbers to each single atom in the assigned unbalanced chemical expressions and use one of the two recommended methods to obtain balanced equations!  Do as many problems as you have time for during your assigned study time and then quit until tomorrow.  Be patient; your practice will make this easier every day!

Start the following in class:

1. Write your journal entry on sheets of three holed 8.5 inch by 11 inch ruled paper in your Journal notebook. In the upper right corner white space of each upward facing page, write your hand in number within a circle followed by your name. Each journal entry should either be at least a paragraph of exemplary writing and penmanship concerning a single topic, or be a concept map relating chemistry terms. Begin each day’s paragraph with a topic sentence, follow with explained instances, and close with a focused summary statement.  Rather than just to find answers to questions, the goal of journaling is to reflect on, synthesize, and clearly express your thoughts in statements of your own understanding, so do not paraphrase material from other sources that you do not understand.

The required focus topics, J165, for today are

a. Explain how the oxidation state of an atom whose oxidation state is not immediately evident from the rules for assigning oxidation numbers can be figured out in a way consistent with the rules for assigning oxidation numbers.  [Hint: Explain how to use the insight that the total of all the oxidation numbers of all the atoms present in a substance is the charge shown to the upper right of the formula for that species in the chemical equation.  [If no charge is shown to the upper right of the formula, the unshown charge is 0 (neutral).]

b. Explain how to determine whether a given balanced chemical expression represents an oxidation-reduction reaction (redox reaction).  Please make your response to this question longer than one sentence.

2.  Download the Oxidation and Reduction flipchart from your MNSD Google Drive > Student Resources > ActivInspire Flipcharts folder or from the Infinite Campus web site.  Read and study the How to Assign Oxidation Numbers document.  Before going on to the next item in today’s home learning activity, review the four rules and six priorities for assigning oxidation numbers to single atoms of elements by heart.  Along with the How to Assign Oxidation Numbers document, the Chapter 20 informational packet is available online at MNSD Google Drive > Student Resources > Handouts > LARN 165 … > Oxidation-Reduction .

a. Assign oxidation numbers to the seven (7) polyatomic oxyanions and one (1) binary molecular compound listed on one of the pages in the chapter 20 informational packet.  Then fill in the Stock name for the first three (3) ions listed.

b. Log onto your MNSD Honors Chemistry Google Classroom.  Study the rules for assigning oxidation numbers given in the document entitled  How to Assign Oxidation Numbers and then take the Google Classroom formative assessment labeled:  Cycle 41 Day 3: QUIZ on Assigning Oxidation Numbers.

3.a.  Use the PQ5R or SQ5R method to prepare study guide for text section 20.3 on Balancing Redox Equations or go to https://socratic.org/chemistry  to research the topics brought up in section 20.3 of your text.  Read section 20.3 in your chemistry text, pages 645 through 649 and pages 653 to 656 and as you do, create a study guide using the SQ5R or PQ5R method explained in class and on the distributed handout packet.  Instead of reading about the ion-electron half reaction method on pages 650-652, review your notes on the method of making the gain of negative charge by single atoms that are reduced equal to the number of negative charges lost by single atoms that are oxidized.  You may record vocabulary entries in the body of your study guide, or you may check them off on the chapter 20 vocabulary list that was distributed as you think about the meanings of the terms and add any notations to the vocabulary list for clarifications sake.

3.b. The SINGLE ATOM RATIO method of balancing chemical expressions using oxidation numbers is explained with step by step examples on the ActivInspire flipchart for Oxidation and Reduction.  Download that flipchart and carefully work through some examples.  Record the following notes on how  to use the SINGLE ATOM RATIO method of balancing chemical expressions using oxidation numbers.

  1. Correctly copy the formula and phase of each reactant and product in the unbalanced chemical expression onto the paper and then draw a short line segment above each atom’s element symbol in each given formula.
  2. Use the rules for assigning oxidation numbers to assign and record the oxidation number for a single atom of each element present in each substance or species on the short line segment drawn above the atom’s elemental symbol in each reactant and product formula, .
  3. If the expression to be balanced represents an oxidation-reduction (redox) process, write a reduction half reaction for a single atom of each substance being reduced and, underneath it,  write an oxidation half reaction for a single atom of each substance being oxidized.
  4. Multiply the half reactions by appropriate multipliers such that the total increase in oxidation number is equal to the total decrease in oxidation number, and then use the resulting ratio of the number of atoms that are reduced to the number of atoms that are oxidized simultaneously to select appropriate coefficients to balance those reduced and oxidized atoms in the chemical expression.
  5. Compute and record the total charge of all the initial state species and compute and record the total charge of all of the final state species, that is, do a charge balance (T check).
  6. In acidic solution, add the necessary number of H+(aq) ions to the side of the chemical expression that needs more positive charge to bring it into charge balance.
  7. In basic solution, add the necessary number of OH –(aq) ions to the side of the chemical expression that needs more negative charge to bring it into charge balance.
  8. Perform a mass balance (another T check) to check that the total number of each kind of atom is the same in the final state as in the initial state.
  9. Bring the hydrogen or oxygen atoms back into balance by adding H2O(l) to the side of the expression that needs more hydrogen or oxygen atoms to bring the expression into mass balance.

c.  After you have finished reading the assigned section of the chapter, answer the formative assessment questions and do some formative assessment problems to inform you about the degree of your comprehension and understanding.  Assessment questions are printed at the end of the section that you have just read.  Reflect on your answers to assure yourself that you have understood the major points in the section that you have just read.  Record your responses to questions that are challenging you, so that you can later review what you are learning.  If all problems seem easy to you, record the response to the problem that was least easy for you to answer.

Writing in blue or black ink, place your hand in number in a circle followed by your name in the upper right white space of a piece of three holed composition paper that hasn’t been written on.  Place the page reference for the problems to be considered to the left of the red marginal line on the first blue line.  Centered on the first blue line, write a descriptive title for the learning activity such as Section C1.4 Responses where C1.4 represents Chapter1.section4.  Before you write your response to each question or problem listed below, write its designation to the left of the red marginal line as listed below, followed by your response in ink to the right of the marginal line.

  • In the Section Assessment 20.3 on page 654, read, analyze, describe and explain practice problems I20-22 (In chapter 20, problem 22), I20-23, and I20-24.
  • Please use the SINGLE ATOM RATIO method of balancing expressions that you used in doing problem I20-21 to do problems I20-25a, b, and c.  For each of the problems I20-25a, b, and c, show all of your work as detailed in the instructions for problem I20-21 above.
  • Study Conceptual Problem 20.4 on page 647 which shows how the oxidation numbers are assigned to atoms according to the rules given on page 639 or according to the rules given in class or in your learning packet handout and then used to identify whether a given chemical reaction involves a reduction process and an oxidation process.
  • Use a properly headed clean sheet of notebook paper to do problems I20-17ab, and I20-18ab.
  • For problems I20-17ab and I20-18ab be sure to skip two lines before copying each chemical equation onto the paper and then drawing a short line segment above each atoms element symbol in each given formula in each equation.
  • On the short line segment drawn above the atoms elemental symbol in each reactant and product formula, use the rules for assigning oxidation numbers to record the oxidation number for a single atom of each element present in each substance or species.
  • If the reaction is an oxidation-reduction (redox) process, write the reduction half reaction for one isolated atom, the oxidation half reaction for one isolated atom, and identify the oxidizing agent and reducing agent in the initial state.
  • For I20-17ab and I20-18ab write half reactions to show which atoms are oxidized and which are reduced.
  • For I20-17ab and I20-18ab use full sentences to identify the oxidizing agent and reducing agent for each chemical reaction.
  • Study Conceptual Problem 20.5 on page 649 which shows how to assign oxidation numbers to atoms according to the rules given on page 639 or according to the rules given in class or in your learning packet handout, and then use those oxidation number assignments to assist in balancing a chemical expression.
  • Use a properly headed clean sheet of notebook paper to do problems I20-19ab, and I20-20ab.
  • For problems I20-19ab and I20-20ab be sure to skip two lines before copying each chemical equation onto the paper and then drawing a short line segment above each atoms element symbol in each given formula in each equation. On the short line segment drawn above the atoms elemental symbol in each reactant and product formula, use the rules for assigning oxidation numbers to record the oxidation number for a single atom of each element present in each substance or species.   If the equation to be balanced represents an oxidation-reduction (redox) process, write a reduction half reaction for a single atom of each substance being reduced, an oxidation half reaction for a single atom of each substance being oxidized, and then multiply the half reactions by appropriate multipliers such that the total increase in oxidation number is equal to the total decrease in oxidation number, and then use the resulting ratio of the number of atoms that are reduced to the number of atoms that are oxidized simultaneously to select appropriate coefficients to balance each chemical expression.
  • ATTENTION — TEXTBOOK ERROR: Please make sure that the formula for tetrahydroxyzincate (II) ion, Zn(OH)42-(aq), is correctly written in problem #21 on page 652 of your textbook!  Also make sure that the formula is written correctly on your assignment paper before you begin to do problem I20-21.
  • Study Conceptual Problem 20.6 on page 652.
  • Do problem I20-21, but use the SINGLE ATOM RATIO method being taught using the Introduction to Oxidation and Reduction flipchart instead of the half reaction method (also known as the ion-electron method) shown in the text.

After you have finished responding to the formative assessment questions and problems, check page R100 of the text and check each of those problems that you can by writing in either a check mark (√) or a correction in green ink.  Write down any question that you still have so that you can ask about it in class.  In the margin of your notebook page, circle the number of formative assessment questions do not have a suggested response given and check your response with that of your classmates when you come to class.

Recommended for those who have time left in their 45 minute study period, but not required of all:

  1. Check out the student made Quizlet for chapter 20 at https://quizlet.com/212581782/ch-20-oxidation-reduction-reactions-flash-cards/.  Do all the definitions reflect a thorough and correct understanding?
  2. Continue to review the meanings of the words on the chapter 1, chapter 2, chapter 3, chapter 4, chapter 5, chapter 7, chapter 8, chapter 9, chapter 10, chapter 11, chapter 12, chapter 13, chapter 14, chapter 15, chapter 16, chapter 17, chapter 18, chapter 19 and chapter 20 vocabulary lists.  Place a – symbol in front of each word that you have to study more, and a change the- to a + symbol in front when you have demonstrated mastery over the word to a study buddy, parent, or friend.
  3. Read and study the Study Guides given on pages 33, 57, 95, 121, 148, 180, 206, 246, 280, 314, 346, 378, 406, 438, 464, 498, 534, 580, 624, and 656 of the text.  Review the Key Concepts for each text section and clarify in your mind under what circumstances would it be helpful to use each of the different relationships shown in the Key Equations section.