CHEM 146 Lab 3 Worksheet | 2

CHEM 146
Lab 3 Worksheet |
2

Lab 3 Worksheet

GRADE ____ /25 p

Your name:

Instructions. Carefully review the material on pages 3 – 8 of the
CHEM 146 Lab 3 Manual (especially the fully worked examples). In this online activity, you are processing and analyzing data identical to what you would obtain in lab.

1. Experimentally Determining KC at 3.8 oC . A student loads 3.0 mL of an ethanol solution of
BDa dye into a cuvette (b = 1.00 cm). Then places the loaded cuvette into a spectrophotometer equipped to maintain the cuvette and its contents at 3.8 oC. She obtains the following equilibrium absorption spectrum at 3.8 oC:


Wavelength: 494 nm

Absorbance: 0.633

Wavelength: 628 nm

Absorbance: 0.438

Determine
KC for this system at 3.8 oC. To receive credit, you must show all work. Remember, first symbolically (with mathematical symbols,
not actual values) state the equation(s). Then, present the
calculation in which actual values are plugged in and the results shown. Be certain sig figs are reasonable
.
You are expected to follow this format in all subsequent lab work without being prompted.

2. Van’t Hoff Analysis. In
Problem 1 above, you obtained
KC at a specific temperature for
BDa. In a similar manner
KC can be determined for
BDa and
BDb over a range of discrete temperatures. Assume, after some effort, you obtain the following
KC vs.
T results for molecular dyes
BDa and
BDb:


KC at Various Temperatures
T for BDa


KC at Various Temperatures
T for BDb


T ( ̊C)


KC


T ( ̊C)


KC

3.8

2.18

1.5

2.26

6.7

1.89

3.4

0.974

9.7

1.61

5.4

0.454

12.9

1.36

7.7

0.185

16.5

1.14

10.1

0.0747

20.1

0.957

12.1

0.0347

23.8

0.814

13.9

0.0168

Using EXCEL determine
H and
S for
each dye

. Paste-in the plots below with the
linear trend-line equation and

R2
adjusted for reasonable sig figs.
Remember, in this course all graphs must be appropriately scaled, titled and labeled. Please remember to do this without further reminders. Include all calculations, that is, show all work to clearly indicate how you determined the enthalpy and entropy values for
BDa and
BDb. (Remember to first symbolically state the equations).

3. Gibbs Free Energy. Given the
H and
S results above,
calculate
G at 1.0 ̊C
for
both
dyes
.
Repeat the calculations for
both dyes, but at 5.0 ̊C
. Show all work. It is highly recommended to carry out the sub-calculations with 4 – 5 significant figures, and only round to the correct SF at the end – this avoids “rounding errors.” Assume
H and
S remain constant over the 1 – 5 ̊C
range.

4. Analysis I. Given the results above, what do the calculated
G results indicate about the directionality (product vs. reactant) of each system (BDa and BDb) at 5.0 ̊C versus 1.0 ̊C?

5. Analysis II. As you know, certain raw vegetables when subjected to freezing temperatures loose desirable qualities such as flavor and firmness. Suppose you are tasked with designing an inexpensive thermochromic thermometer that can be attached to vegetable shipping pallets and indicate if freezing temperatures exist. In this application the thermometer must sharply undergo a chromic shift (give a rapid, distinct color change) around 2 – 4 ̊C. Given the results from
Questions 2 – 4 above, and assuming the ε and
λmax values of both dyes are essentially identical, which dye,
BDa or
BDb, would be the best choice for such a thermochromic thermometer? Clearly justify your claim using the relevant data. To receive credit, you must respond with well written, very legible, complete sentences that correctly employs chemical terminology and concepts.

146 Lab 3 Worksheet
v1.4

MY © 2022
7-14-22
UA-CBC Technical Press, University of Arizona

image1.jpeg

image2.jpeg

#CHEM #Lab #Worksheet

Share This Post

Email
WhatsApp
Facebook
Twitter
LinkedIn
Pinterest
Reddit

Order a Similar Paper and get 15% Discount on your First Order

Related Questions

Prompt: Apply Allport’s, Cattell’s, or Eysenck’s theories to the

Prompt: Apply Allport’s, Cattell’s, or Eysenck’s theories to the Week 5 Case Conceptualization Download Week 5 Case Conceptualization . You are being asked to conceptualize this case by explaining how this person’s current personality dynamics and presenting problems have developed, what is helping to maintain them in the present, and

What are health behaviors? Identify the seven health behaviors. What

What are health behaviors? Identify the seven health behaviors. What does research suggest about the consequences of these health behaviors? Response Parameters: · Use APA-style format for references · At least 400 words · in-text citations · Peer-reviewed references #health #behaviors #Identify #health #behaviors

UBER Purpose:  The purpose of this assignment is to analyze a

UBER Purpose:  The purpose of this assignment is to analyze a successful organization and learn from what makes them such a success.  This paper will allow you to delve into the successful operations to analyze its satisfaction, CEO leadership, career opportunities, and compensation and benefits, among others in order to extract best

Instructions Read “Chapter 1: Why Public Speaking Matters

Instructions Read “Chapter 1: Why Public Speaking Matters Today,” which can be accessed through the  Course Resources, and watch the following general education video. Then, in one to two paragraphs, discuss what you have learned about the importance of General Education and highlight some of the reasons why having public

Instructions Make sure you label each part of your initial

Instructions Make sure you label each part of your initial post and submit your response by typing directly in the discussion tool rather than attaching your response as a Word document. This will ensure other students can easily access your post. Direct Link:  The danger of silence | Clint Smith

Assume you were counseling people with the following presenting

Assume you were counseling people with the following presenting problems.  James My fear is that I am empty and vacant inside. I’ve never really had to look at myself before now, but since my husband left me, I am lost. I feel deserted, abandoned, isolated, and fear that I cannot

Discuss about the following articles: 1- An antitrust case brought by

Discuss about the following articles: 1- An antitrust case brought by the Department of Justice (DOJ) against Google 2- Article regarding a tax fraud court case that Hunter Biden was subject to attend on January 11, 2024, for numerous accusations of failing to file and pay taxes for the 2016

Hellfire Pistons Motorcycle Gang Study [Note: To complete this

Hellfire Pistons Motorcycle Gang Study [Note: To complete this template, replace the bracketed text with your own content. Remove this note before you submit your presentation.] [Your Name] CJ 340: Criminology [Date] Crimes [Identify crimes in relation to this gang.] Offenders [Describe the offenders who commit crimes.] Sociology → Criminology

Reflect in ePortfolio Download Print Open with docReader Module Five

Reflect in ePortfolio Download Print Open with docReader Module Five Journal Guidelines and Rubric CJ 340 Module Five Journal Guidelines and Rubric Overview In this journal assignment, you will reflect on how cultural views and values influence delinquency and criminal behavior, what subcultures are, and how subculture theories explain criminal

1. Which curriculum you are using for Math, ELA, Science and Social

1. Which curriculum you are using for Math, ELA, Science and Social Studies? 2. Does these curriculum meet your students needs? How do you know? 3. Is the curriculum culturally relevant? How do you know? 4. During the lesson, what factors contributed to your decision to ask low cognitive and more

For some, advocacy might conjure images of speaking at a congressional

For some, advocacy might conjure images of speaking at a congressional hearing or soliciting petition signatures at library entrances. Yet, social workers engage in advocacy as an agent of social change in numerous ways: • Case advocacy—When a social worker addresses the lack of services or resources at the micro

Increased stress and anxiety, feelings of hopelessness, a history of

Increased stress and anxiety, feelings of hopelessness, a history of trauma, and lack of social support can all put adolescents at increased risk for suicide. These are largely internal risk factors, hidden from others. How might they manifest as warning signs observable by others? Social workers—particularly those in schools—are poised

C/ACC501 Accounting For Decision Making Module 3 Case TRANSFER

C/ACC501 Accounting For Decision Making Module 3 Case TRANSFER PRICING AND RESPONSIBILITY CENTERS Assignment Overview Coffee Maker’s Incorporated (CMI) Three divisions of a CMI are involved in a dis #CACC501 #Accounting #Decision #Making #Module #Case #TRANSFER