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LARN 147 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 set of required focus topics, J147A for today is

a. For a closed system at equilibrium, what is the effect on the rate of an exothermic forward reaction when

1) the temperature of the system is increased?  Give the reasoning for your answer.

2) the concentration of a reactant is increased?  Give the reasoning for your answer.

3) more solid reactant is added to the equilibrium mixture?  Give the reasoning for your answer.

4) a catalyst is added to the equilibrium mixture?  Give the reasoning for your answer.

5) when an inhibitor (a catalyst poison) is added to the equilibrium mixture?  Give the reasoning for your answer.

     b. For a closed system at equilibrium, what is the effect on the rate of an endothermic reverse reaction when

1) the temperature of the system is increased?  Give the reasoning for your answer.

2) the concentration of a product is increased?  Give the reasoning for your answer.

3) more solid product is added to the equilibrium mixture?  Give the reasoning for your answer.

4) a catalyst is added to the equilibrium mixture?  Give the reasoning for your answer.

5) when an inhibitor (a catalyst poison) is added to the equilibrium mixture?  Give the reasoning for your answer.

B. The second set of required learning journal questions, J147B, for today is as follows.

  1. What is the difference between an equilibrium constant expression, Keq, and the value of the equilibrium constant at a given temperature?
  2. What is the difference between an equilibrium constant expression, Keq, and a solubility product constant expression, Ksp ?
  3. If the value of an equilibrium constant is much greater than unity,  Keq >> 1, what does that mean about the relative amounts of products and reactants present in the equilibrium state?
  4. If the value of an equilibrium constant is equal to unity, Keq = 1, what does that mean about the relative amounts of products and reactants present in the equilibrium state?
  5. If the value of an equilibrium constant is much less than unity, Keq << 1, what does that mean about the relative amounts of products and reactants present in the equilibrium state?  Please make your response longer than one sentence.
  6. The value of the solubility product constant, Ksp, for silver sulfide dissolving in water is about 8.0 · 10– 51.  What does the size of this value indicate about the solubility of silver sulfide in water?   Please make your response longer than one sentence.

2.a.  Use the PQ5R or SQ5R method to prepare study guide for text section 18.3 on Solubility Equilibrium or go to https://socratic.org/chemistry  to research the topics brought up in section 18.3 of your text.  Read section 18.3 in your chemistry text, pages 560 through 565, 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.

First study these concepts:

  1. The point of an equilibrium or position of an 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.
  2. 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.
  3. 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.
  4. 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.
  5. A chemical species is an atom, ion, or molecule.

Make sure you understand the following ideas:

  1. The predictions of Le Châtelier’s principle can be understood using the collision theory of reactions. When a stress is imposed, whichever state (initial or final) that experiences a greater increase in the number of collisions will result in the rate of that (forward or reverse) reaction (respectively) increasing more than the rate of its opposing reaction.
  2. 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.
  3. 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.
  4. 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 has no additional effect.
  • Study Conceptual Problem 18.1 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. This problem is found on page 555 in the text.  Answer the questions and explain your reasoning for practice problem I18-6abcd (In chapter 18, problem 6abcd).
  • Study Sample Problem 18.3 on page 562.  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.   Circle and express the calculated result to the proper number of significant figures. Show your work for practice problems I18-17 (In chapter 18, problem 17) and I18-18.  For each problem show

a. the correctly written balanced expression for the dissolving of the solute into water,

b. the solubility product constant expression set equal to the numerical value of the solubility product constant,

c. substitutions for the concentrations of the various species represented in the solubility product constant expression , and

d. the final solving for the value of the unknown variable set with that variable ultimately set equal to the sought for answer expressed to an appropriate number of significant figures.

  • Study Sample Problem 18.4 on page 564. 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.   Circle and express the calculated result to the proper number of significant figures.
  • Show your work for practice problems I18-19 (In chapter 18, problem 19) and I18-20.  For each problem show

a. the correctly written balanced expression for the dissolving of the solute into water,

b. the solubility product constant expression set equal to the numerical value of the solubility product constant,

c. substitutions for the concentrations of the various species represented in the solubility product constant expression , and

d. the final solving for the value of the unknown variable set with that variable ultimately set equal to the sought for answer expressed to an appropriate number of significant figures.

  • In the Section Assessment 18.3 on page 565, read, analyze, describe and explain practice questions I18-21 (In chapter 18, problem 21) and I18-22, and then show your work including all conversion ratios for problems I18-23, I18-24, I18-25, I18-26, I18-27ab [Explain], and I18-28.  For each problem show

a. the correctly written balnced expression for the dissolving of the solute into water,

b. the solubility product constant expression set equal to the numerical value of the solubility product constant,

c. substitutions for the concentrations of the various species represented in the solubility product constant expression , and

d. the final solving for the value of the unknown variable set with that variable ultimately set equal to the sought for answer expressed to an appropriate number of significant figures.

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. 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, and chapter 18 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.

2. Study the Key Concepts given on pages 33, 57, 95, 121, 148, 180, 206, 246, 280, 314, 346, 378, 406, 438, 464, 498, 534, and 580 of the text.