Loading...

Messages

Proposals

Stuck in your homework and missing deadline? Get urgent help in $10/Page with 24 hours deadline

Get Urgent Writing Help In Your Essays, Assignments, Homeworks, Dissertation, Thesis Or Coursework & Achieve A+ Grades.

Privacy Guaranteed - 100% Plagiarism Free Writing - Free Turnitin Report - Professional And Experienced Writers - 24/7 Online Support

Least count of pipette in chemistry

22/10/2021 Client: muhammad11 Deadline: 2 Day

Lab 6: Determination of Ka for a Weak Acid

Procedure: To begin the experiment, carefully cut the tip of the phenolphthalein pipet and add exactly 2 drops of phenolphthalein solution to the unknown weak acid in the beaker. Then swirl the beaker to completely mix the unknown weak acid and phenolphthalein solution. Remove the cap of the Sodium Hydroxide and fill an empty pipet full of the solution. Add NaOH from the pipet into the beaker containing the 4 mL of unknown weak acid one drop at a time, swirling and observing the solution in the beaker after each drop until the color changes to a pale-pink color for at least 5 seconds. Count and record each drop of NaOH added to the beaker, so that you will know exactly how many drops of NaOH were required to cause the solution to change from clear and colorless to pale-pink in color. Next, carefully pour the solution down the sink drain and use the dish soap, tap water, and paper towels to wash and dry the beaker. Repeat, observe, and record. Next, add exactly 10 drops of NaOH from the pipet into the beaker containing the 4 mL of unknown. Gather a pH indicator strip from the kit and place it into the solution in the beaker so that all 4 indicator squares come into contact with the weak acid. Accurately read the pH indicator, record, and repeat. After finishing the experiment, calculate the percent error based on the results that was gathered throughout the experiment.

Exercise 1:

1. Using the data collected in Data Table 2, create a graph of “Drops of NaOH added” vs “pH” where “drops of NaOH added” is on the x-axis and “pH” is on the y-axis. Upload an image of the graph into Graph 1.

C:\Users\hall\Desktop\chart 1.jpg

2. pH indicator strips work by changing color in the presence of solutions with varied pH values. Thinking about your procedure steps and results in Part 1, why do you think the pH of the unknown weak acid was not determined with pH indicator strips until Part 2?

We use the pH indicator strips to calculate the amount of unknown acid in the receiving flask by measuring the specific amount of base it takes to neutralize the acid. There are two major ways to know when the solution has been fully neutralized. The first uses a pH meter in the beaker by slowly adding base until the pH reads exactly 7 (neutral). The next method uses a specific indicator. An indicator is an acid or base whose conjugate acid or base has a color difference from the original compound. The color changes when the solution contains a 1:1 ratio mixture of the differently colored forms of the indicator. The pH equals the p K a of the indicator at the endpoint of the indicator. Since the pH of the solution is known and the volume of titrate is added, we can then deduce how much base was needed to neutralize the unknown sample.

3. Discuss possible causes of error in the experimental procedure. Why do you think there was a percent of error in the pKa and Ka values of the unknown weak acid, in comparison to the values presented in Table 2?

My results were close with a 5% Ka error. This error could have come from the pH key, which may not have been 100 percent read precisely. Also, incorrect measuring of solutions when preparing the experiment could have resulted in error.

4. Do you think using a pH meter instead of pH indicator strips would have created a larger or smaller percent error? Explain your answer.

A pH meter has to be specifically calibrate correctly, so if this was calibrated incorrectly, it could also result in error, however I think that there would be a less of a percent error because a meter instrument is more accurate than strips and gives an exact numerical measurement.

5. Why was phenolphthalein a good indicator to use for determining the equivalence point between the unknown weak acid and strong base?

Phenolphthalein is a great indicator for determining the equivalence point. Is a suitable indicator for strong acid or a strong base. It is also a good indicator for a weak acid or strong base therefore it works well in this experiment.

Data Table 1: Determination of Equivalence Point

Trial 1

Trail 2

Volume of Unknown weak Acid

4ml

4ml

Total number of Drops required to reach equivalence point

114 required drops

104 required drops

Average Number of Drops

Average: 109

Data Table 2: Titration Curve Values

Drops NaOH added

pH Value Trial 1

pH Value Trail 2

pH Value Average

Half-Equivalent Point

54

54

5.0

Equivalent Point

109

109

0

3

1

1

10

2.5

2.5

2.5

20

3

3

3.25

30

3.5

3.5

4

40

4

4.5

4.25

50

4.5

5

4.75

60

5

5.5

5.5

70

6

6

6

80

6.5

6.5

6.5

90

7

7.25

7.5

100

7.5

7.5

7.75

110

8

8

8

120

11

11.5

12

Panel 1: Equivalent Point Number of Drops

The Equivalent Point= 93 Drops

Panel 2: Half- Equivalent Point Number of Drops

The Half- equivalent point= 46 Drops

Data Table 3: Determination of Unknown

pKa of Unknown Weak acid

5.0

Ka of Unknown Weak Acid

.00001

Unkown Weak Acid Identity

Acetic Acid

% Error pka

-44%

% error Ka

5%

C:\Users\hall\Desktop\4.jpg C:\Users\hall\Desktop\3.jpg C:\Users\hall\Desktop\pic 1.jpg C:\Users\hall\Desktop\3.jpg

Conclusion:

This lab demonstrated how a titration can be used to measure the concentration of an weak or strong acid or base in solution. This experiment allowed me to practice how to calculate the molar mass of an unknown acid or base, and determine the equilibrium constant of a weak acid (Ka) or weak base (Kb). By adding NaOH, a strong base, in small increments, it was possible to determine the equivalence point of NaOH and the unknown weak acid. Then, the pH at equilibrium was used in order to find the concentration of the unknown acid at equilibrium. In addition, by using the mass of the unknown weak acid and its concentration at equilibrium, the molar mass of the acid was determined. Finally, by using the equation pKa = -log(Ka) and the half equivalence point pKa, the value of Ka for the unknown weak acid was found.. Even though, I had a 5% error, I still believe I conducted this experiment to the best of my ability. I really enjoyed this lab and would recommend people to try it.

Homework is Completed By:

Writer Writer Name Amount Client Comments & Rating
Instant Homework Helper

ONLINE

Instant Homework Helper

$36

She helped me in last minute in a very reasonable price. She is a lifesaver, I got A+ grade in my homework, I will surely hire her again for my next assignments, Thumbs Up!

Order & Get This Solution Within 3 Hours in $25/Page

Custom Original Solution And Get A+ Grades

  • 100% Plagiarism Free
  • Proper APA/MLA/Harvard Referencing
  • Delivery in 3 Hours After Placing Order
  • Free Turnitin Report
  • Unlimited Revisions
  • Privacy Guaranteed

Order & Get This Solution Within 6 Hours in $20/Page

Custom Original Solution And Get A+ Grades

  • 100% Plagiarism Free
  • Proper APA/MLA/Harvard Referencing
  • Delivery in 6 Hours After Placing Order
  • Free Turnitin Report
  • Unlimited Revisions
  • Privacy Guaranteed

Order & Get This Solution Within 12 Hours in $15/Page

Custom Original Solution And Get A+ Grades

  • 100% Plagiarism Free
  • Proper APA/MLA/Harvard Referencing
  • Delivery in 12 Hours After Placing Order
  • Free Turnitin Report
  • Unlimited Revisions
  • Privacy Guaranteed

6 writers have sent their proposals to do this homework:

Academic Mentor
Writing Factory
24/7 Assignment Help
Top Writing Guru
Essay Writing Help
Top Rated Expert
Writer Writer Name Offer Chat
Academic Mentor

ONLINE

Academic Mentor

As an experienced writer, I have extensive experience in business writing, report writing, business profile writing, writing business reports and business plans for my clients.

$36 Chat With Writer
Writing Factory

ONLINE

Writing Factory

I can assist you in plagiarism free writing as I have already done several related projects of writing. I have a master qualification with 5 years’ experience in; Essay Writing, Case Study Writing, Report Writing.

$31 Chat With Writer
24/7 Assignment Help

ONLINE

24/7 Assignment Help

Being a Ph.D. in the Business field, I have been doing academic writing for the past 7 years and have a good command over writing research papers, essay, dissertations and all kinds of academic writing and proofreading.

$34 Chat With Writer
Top Writing Guru

ONLINE

Top Writing Guru

As per my knowledge I can assist you in writing a perfect Planning, Marketing Research, Business Pitches, Business Proposals, Business Feasibility Reports and Content within your given deadline and budget.

$42 Chat With Writer
Essay Writing Help

ONLINE

Essay Writing Help

I find your project quite stimulating and related to my profession. I can surely contribute you with your project.

$29 Chat With Writer
Top Rated Expert

ONLINE

Top Rated Expert

I am an academic and research writer with having an MBA degree in business and finance. I have written many business reports on several topics and am well aware of all academic referencing styles.

$33 Chat With Writer

Let our expert academic writers to help you in achieving a+ grades in your homework, assignment, quiz or exam.

Similar Homework Questions

Westan corporation uses a predetermined overhead rate - Ivan franko national university of lviv - Purpose: This assignment is designed to assess your level of knowledge of the key topics covered in this unit - Avanti italian textbook characters - Avicel for plaque assay - Flexible Budgeting - Innovative marketing strategies ppt - Competency and image enhancement as a means of addressing devaluation - Home work ch 11 - Ngo and sons timetable - The included angle between the sides of v belt is - Applying the roper-logan-tierney model in practice read online - Families of elements worksheet answer key - Kilbridge and wester method example - Chemistry matter and its changes 5th edition pdf - Assignment 7 - The execution of wanda jean movie - Hall company manufactures a single product - What does ayri fik mean - 13th netflix discussion questions - Lancashire grid for learning email - Example of sociocentrism in life - Air cycle cooling system in aircraft - Spelling city splat n spell - Cover letter for criminal justice graduate - Week 4 Discussion Question - As nzs 2161 occupational protective gloves - conduct research and prepare a five-page scholarly paper on the crime of murder - Here i am morris chapman chords - Matt cutts ted talk - The economic advantages of cultural diversity in australia - MANAGING CAREER - Order 2236817: Creating and Communicating a Security Strategy - Big bang balloon lab answers - Inlanguage boutique brunswick east - In basket exercise in hrm - Geometry Online experts - Renewable composite insulation material - The adjusted trial balance columns - There's a boy in the girls bathroom sparknotes - Molecules generated from butter will enter aerobic cellular respiration at - St george netball association - Refer to figure 11-1. the marginal product of the 7th worker is - Debit and credit theory - Disney erp system - Describe the habits of successful interface designers - Bratt pan safety procedures - Affective objectives for physical education - HI150 Automation of Health Information - Under armour financial statements 2016 - Drywall repair clips home depot - The adma code of practice - Stonefields reserve cabernet sauvignon 2017 - Chris21 self service login - What is 70kg in pounds - Environmental ethics desjardins 5th edition pdf - Cosh x in terms of e - 19/14 warringah road mosman - Trust works ken blanchard pdf - Ancient greek newspaper project examples - LITERATURE - Benny hinn ministries australia - Returned Foreign Terrorist Fighters - Romanian language writing systems - What makes australia unique - Titanic sinking from the icebergs perspective - ?? same-day +27833173182 mokhotlong" ABORTION CLINIC // PILLS,,,, - Is the self ionisation of water endothermic - Questions - Helium at room temperature - QNT561 Week 2 Case Study MBA Schools in Asia-Pacific - An american childhood critical thinking answers - Duke public policy phd - Law Exam - Distance from home to 2nd base - What does the name christian mean - Lymphoscintigraphy cpt code - The graveyard book character list - Boring, tedious jobs generally reduce people's perceptions of their - Why does the international date line exist - Teaching project - Powder transfer system design - Why do mice run in circles - 145 ft lbs to nm - New skool grooves case study - Rhetorical Appeals and Devices - Https youtu be ji5_mqicxso - Reading and Essay - 4 types of reinforcement schedules - Miles hodges 11 things i shoulda said - Maladaptive response to psoriasis - Yarn measure equivalent to 18 hanks - Butl_ Learnign Feamework - Word document edit - Motivation biological psychological and environmental 3rd edition pdf - Research paper - Case study - Colleges prepare for life freeman hrabowski - Controversies in media ethics 3rd edition - Chapter 2 health care systems review questions