by horse Comment Closed

LARN 122 C31D2

Start the following in class:

1.a.  Solvation is the process of solute particles becoming surrounded by solvent molecules which are attracting the solute particles through “intermolecular forces of attraction”.  The term intermolecular forces of attraction includes not only London dispersion force attractions but also includes ion-dipole interactions and dipole-dipole interactions.  If the solvent is water, the solvation process can be called hydration.

Examine the  different animation action close ups of formula units of a substance dissolving at 

  1. https://www.youtube.com/watch?v=EBfGcTAJF4o
  2. https://www.youtube.com/watch?v=CLHP4r0E7hg
  3. https://www.youtube.com/watch?v=zePYWZ2AjnI
  4. https://www.youtube.com/watch?v=IPQzY34eCt4
  5. https://www.youtube.com/watch?v=aKGJm6OGJNs
  6. https://www.youtube.com/watch?v=xdedxfhcpWo
  7. https://www.youtube.com/watch?v=JAWiJKhmbQc  List some things wrong with the previous simulations of dissolving salt
  8. Salt vs. Sucrose

Note:  One must wait for each animation to be over before the buttons for the other animations appear.

The required focus topics, J122A for today are

a. Describe the process of an ionic solute such as sodium chloride, NaCl, dissolving in water and making an aqueous sodium chloride solution.  Please make your answer to this question longer than one sentence.

b. Construct two or more well labeled diagrams to make your points about the solvation of the positive and negative ions and the dissolving of the crystals of sodium chloride.

c.   What is the process of ionic dissociation?  Please make your answer to this question longer than one sentence.

d.  Write a balanced chemical expression for the dissociation and hydration of CaCl2 solid when it dissolves in water.  By convention, leave the formula, H2O(l) out of both the initial and final states of the chemical equation.

e.  What is meant by the term hydration?

1.b. The first required focus question, J122B, for today is

An electrolyte is a substance that conducts an electric current when dissolved in water or when melted.  Explain:

  1. Why are most covalent molecular substances such as oxygen, O2; nitrogen, N2; glucose, C6H12O6; and ethanol, CH3CH2OH nonelectrolytes?  Use a separate sentence to clarify why each named substance is a nonelectrolyte.
  2. Why some covalent molecular substances such as carbon dioxide, CO2; ethanoic acid, CH3COOH; and ammonia, NH3 that react slightly with water are weak electrolytes?  Use a separate sentence to clarify why each named substance is a weak electrolyte.
  3. Why ionic compounds such as sodium chloride, NaCl; calcium chloride, CaCl2; potassium chloride, KCl; hydrochloric acid, HCl(aq), and sodium hydroxide, NaOH are strong electrolytes?  Use a separate sentence to clarify why each named substance is a strong electrolyte.

2.a.  Use the PQ5R or SQ5R method to prepare study guide for text section 15.2 on Homogeneous Aqueous Systems or go to https://socratic.org/chemistry  to research the topics brought up in section 15.2 of your text.  Read section 15.2 in your chemistry text, pages 450 through 458, 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 15 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.  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 [chapter #.section#] Responses.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.

  • Study Conceptual Problem 15.2 on page 456 and then show your work including all conversion ratios for practice problems I15-6 (In chapter 15, problem 6) and I15-7.
  • In the Section Assessment 15.2 on page 457, read, analyze, describe and explain practice problems I15-7 (In chapter 15, problem 7) and I15-8, I15-9, I15-10, I15-11; I15-12abcdef and a, b, c, d, e, f; I15-13ab, I15-14abc, and then show your work including all conversion ratios for practice problem 15-15.

After you have written your best effort response for each assigned item, check page R94 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 as we do in 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 15 at Water and Aqueous Systems  Do all the definitions reflect a thorough and correct understanding?

2. Review the SI prefixes and their meanings until you can readily explain the meaning of each listed SI prefix as a numerical multiplier.