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

Determination of ka for a weak acid lab answers

20/10/2021 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:

A Grade Exams
Instant Assignment Writer
Homework Guru
Top Writing Guru
Professional Coursework Help
Pro Writer
Writer Writer Name Offer Chat
A Grade Exams

ONLINE

A Grade Exams

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

$38 Chat With Writer
Instant Assignment Writer

ONLINE

Instant Assignment Writer

I reckon that I can perfectly carry this project for you! I am a research writer and have been writing academic papers, business reports, plans, literature review, reports and others for the past 1 decade.

$24 Chat With Writer
Homework Guru

ONLINE

Homework Guru

I have written research reports, assignments, thesis, research proposals, and dissertations for different level students and on different subjects.

$47 Chat With Writer
Top Writing Guru

ONLINE

Top Writing Guru

I will be delighted to work on your project. As an experienced writer, I can provide you top quality, well researched, concise and error-free work within your provided deadline at very reasonable prices.

$40 Chat With Writer
Professional Coursework Help

ONLINE

Professional Coursework Help

I have worked on wide variety of research papers including; Analytical research paper, Argumentative research paper, Interpretative research, experimental research etc.

$48 Chat With Writer
Pro Writer

ONLINE

Pro Writer

I am an experienced researcher here with master education. After reading your posting, I feel, you need an expert research writer to complete your project.Thank You

$32 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

Martin luther king 5 paragraph essay - Practice marketing simulation - Under armour inventory turnover ratio - Keefe 1979 learning styles - Foreign direct investment by cemex - Cream stone paint colour - Culture and values 8th edition pdf - Camero shots and angles - Hydraulic fracturing pros and cons chart - Maths methods unit 1 and 2 practice sacs - Nissan maxima won t start - Seminar report on computer networking - Emerson ups liebert gxt mt+ manual - Internet Marketing - Peacocks medical group ltd - Whole foods market 2015 annual report - Www sbha org uk - Apparition of our lady of la salette summary - Privilege power and difference 3rd edition pdf - Mechanical engineering projects title - Difference between business continuity and disaster recovery ppt - Ocr gcse history past papers 2015 - Lexical analyzer generator lex - Disability access certificate fee - Writing effective board papers - Intuitive solutions pizza hut santa rosa - A doll's house monologue nora - Advantages and disadvantages matrix structure - Cave diving papua new guinea - Convolution of two gaussians - Research Paper - Bcg matrix case study with solution - Find quadratic equation given roots and leading coefficient calculator - Exercise 15 7 crawford corporation incurred the following transactions - Markel practical strategies for technical communication - Develop a hypothesis relating to the amount of dissolved oxygen - The happiest refugee transcript - Vin number 4 country - What can you buy in mexico with 1000 pesos 2017 - How much yen per dollar - TCP/IP Attack Lab- SEED Labs Project - The last mountain movie worksheet answers - Kerbin geostationary orbit calculator - Four sector circular flow model diagram - Excel gantt chart exclude weekends - Positive role model qualities - Medidata rave user guide - How many faces does a coin have - Acc 202 final project workbook - My cousin vinny essay - Addison inc uses a perpetual inventory system - What is the mass in grams of 7.35 mol water - Ki na2s2o3 k2s2o8 starch - Needy paws animal shelter - Chemistry - Genius gluten free pain au chocolat - Statistics - Zf s5 39 transmission - Uts library apa referencing - Cmit 425 risk assessment paper - Discussion: Clinical Supervision week 5 - Frosted flakes marketing strategy - Business name register victoria - Cyte suffix meaning - Dog registration moreton bay - 93 little hobart street welch wv - Diversified Risk Stock Portfolio - Case study - Hcf health insurance packages - 7 domains of a typical it infrastructure - Csu duscussion - Iinet net au voipsetup - Stage 3 spelling program - Barriers caused by organizational culture encountered by nurse leaders - Pp slide quick turn - Medicare item number 00023 - Introduction to ionic bonds - Management Project - How to do g's secret mission - Creating an activity series of metals lab - Tim hortons target customer - Cloud computing - Soap note for nausea and vomiting - Nursing leadership - Walmart recruiting store sales forecasting - Padhe likhe jahil meaning in english - Adp payroll login mss security - World and screen nicholas carr summary - Thomas eaton book of secrets pdf - What was the titanics top speed - Biology in motion atp - Six kingdoms of life characteristics - Chapter Summaries(1 & 2)- 2 pages - Semi log graph paper gel electrophoresis - Draw a hexagon in a circle - Julian rotter locus of control - Pros and cons of university - Bayonne packaging inc pdf - 21 multiple choice and 1 short essay for an exam(media and theories - Manpower consultancy company profile ppt