by horse Comment Closed

LARN 146 C37D2

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.

a.  The first required focus topic, J146A, for today is

Please make your responses to all questions longer than one sentence. What is the effect on the rate of the forward reaction when

  1. the temperature of the system is increased?   Give the reasoning for your prediction.
  2. the concentration of a reactant is increased?  Give the reasoning for your prediction.
  3. the particles of a reactant solid are ground more finely before adding them to the reaction mixture?  Give the reasoning for your prediction.
  4. a catalyst is added to the reaction mixture?  Give the reasoning for your prediction.
  5. when an inhibitor (a catalyst poison) is added to the reaction mixture?  Give the reasoning for your prediction.

b. The second required learning journal topic J146B, for today is

     What is the effect on the rate of the reverse reaction when

  1. the temperature of the system that is not yet at equilibrium is increased?  Justify your prediction with one or more sentences of reasoning.
  2. the concentration of a product is increased?  Justify your prediction with one or more sentences of reasoning.
  3. the particles of a product solid are ground more finely and added to the reaction mixture that is not yet at equilibrium? Justify your prediction with one or more sentences of reasoning.
  4. a catalyst is added to the reaction mixture that is not yet at equilibrium?  Give the reasoning for your prediction.
  5. when an inhibitor (a catalyst poison) is added to the reaction mixture?  Justify your prediction with one or more sentences of reasoning.

2.a. Use the PQ5R or SQ5R method to prepare study guide for text section 18.2 on Reversible Reactions and Equilibrium or go to https://socratic.org/chemistry  to research the topics brought up in section 18.2 of your text.  Read section 18.2 in your chemistry text, pages 549 through 559, and as you do, create a study guide using the SQ5R or PQ5R method explained in class and on the distributed handout packet. You may record vocabulary entries in the body of your study guide, or you may check them off on the chapter 18 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

2.b.  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.

If solving the problem entails the use of multiplication or division, show your work by including a ? followed by the unit of the quantity you are solving for, an = sign, followed by the quantity given that has all or part of the dimensions of whatever quantity you are solving for, followed by mathematical operations on all labeled quantities, conversion ratios or comparison ratios that are used to obtain the sought for quantity.

  1. First review these concepts:  The point of any equilibrium or position of any equilibrium is a measure of the relative concentrations of products to reactants and is a measure of the progress of the reaction from reactants to products.  A stress exerted on a system at equilibrium is a change in temperature, a change in concentration of a reactant or product present in the equation for the reaction, or a change in pressure of one or more gaseous reactants or products that is imposed on the system at equilibrium.  A chemical system composed of chemicals that can or did react is at equilibrium if no material is entering or leaving the system, if the temperature is constant, and if there is no net change in the concentrations and/or amounts of chemicals in the system.  Le Châtelier’s principle is the generalized observation that a system at equilibrium responds to an imposed stress by changing its point of equilibrium in such a way that the stress is minimized.  A chemical species is an atom, ion, or molecule.
  2. Make sure you understand the following ideas: Le Châtelier’s principle is equivalent to a conclusion from the collision theory of reactions that when a stress is imposed, the rate of the forward reaction typically either increases or decreases more than the the rate of the reverse reaction. If the concentration or pressure of a reaction species is increased, the reaction species will collide more frequently and thus speed up the reaction that consumes that species as a reactant.  If the temperature of a system increases, the rate of both forward and reverse reactions will increase, but the rate of the reaction that can absorb the extra thermal energy available, the endothermic reaction, will speed up the most.  Adding a catalyst speeds up both the forward and reverse reactions so that equilibrium is attained faster, but if the system is already at equilibrium, the addition of the catalyst or the poisoning of the catalyst would have no additional effect.
  3. Study Conceptual Problem 18.1 on page 555 in the text which shows how to apply Le Châtelier’s Principle to predict the change in the position of equilibrium of reversible reactions that are subjected to an external stress. Answer the questions and explain your reasoning for practice problems I18-6abcd (In chapter 18, problem 6abcd).
  4. Study Sample Problem 18.1 on page 557 of the text which shows how to write an equilibrium constant expression for a [closed] system at equilibrium [at constant temperature] and then how to calculate the [constant] value for the equilibrium constant expression by substituting in the equilibrium concentrations of products and reactants using the same units for each. Then and only then, do practice problems I18-7 (In chapter 18, problem 7) and I18-8ab. Show your work in detail as you do the problems. Be sure to include the units of each measured quantity, to cancel all units that are both in a numerator and a denominator of multiplied ratios, and to label the resulting units of each calculated value. Also circle and express the calculated result to the proper number of significant figures.
  5. Study Sample Problem 18.2 on page 558 which is another example of how to write an equilibrium constant expression for a system at equilibrium and then how to calculate the value for the equilibrium constant expression by substituting in the equilibrium concentrations of products and reactants using the same units for each. Then and only then, do problems I18-9 (In chapter 18, problem 9) and I18-10. Show your work in detail as you do the problems. Be sure to include the units of each measured quantity, to cancel all units that are both in a numerator and a denominator of multiplied ratios, and to label the resulting units of each calculated value. Also circle and express the calculated result to the proper number of significant figures.
  6. In the Section Assessment 18.2 on page 559, read, analyze, describe and explain practice problems I18-11 (In chapter 18, problem 11), I18-12, I18-13, I18-14, I18-15, and I18-16abc and abc[Explanations].

After you have finished responding to the formative assessment questions and problems, check page R97 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. How do the properties of covalent molecular substances with hydrogen bonding typically differ from those covalent molecular substances that form molecules whose van der Waals attractive forces only weakly attract other molecules?
  2. Think about the sixteen properties of covalent molecular substances listed on the Properties to be understood worksheet describing differences in the properties of metals, ionic compounds, covalent network solids, and covalent molecular compounds.  Continue to study this handout for understanding and review how the typical properties of members of these classes of compounds depend on whether the compound has localized or delocalized electrons, and upon whether strong metallic, ionic, or covalent bonding or weak van der Waals forces of attraction are predominant between representative particles of the substances.  Try to understand how each property of a given covalent molecular substance is related to the groups of covalently bonded atoms that form molecules whose van der Waals attractive forces only weakly attract other molecules.