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

How do ph indicator strips work

28/10/2021 Client: muhammad11 Deadline: 2 Day

Cailin Winokur

Professor Stage

Chemistry II

March 18, 2018

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:

High Quality Assignments
Unique Academic Solutions
Homework Master
Solution Provider
Homework Guru
Assignments Hut
Writer Writer Name Offer Chat
High Quality Assignments

ONLINE

High Quality Assignments

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.

$35 Chat With Writer
Unique Academic Solutions

ONLINE

Unique Academic Solutions

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.

$39 Chat With Writer
Homework Master

ONLINE

Homework Master

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

$29 Chat With Writer
Solution Provider

ONLINE

Solution Provider

I have read your project description carefully and you will get plagiarism free writing according to your requirements. Thank You

$48 Chat With Writer
Homework Guru

ONLINE

Homework Guru

I have read your project description carefully and you will get plagiarism free writing according to your requirements. Thank You

$48 Chat With Writer
Assignments Hut

ONLINE

Assignments Hut

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.

$36 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

How to draw an isobar map - Four loko dan murphy's - What's stifling the creativity at coolburst - Stevenage bus times sb1 - How to write a criminology report - Cotton cushion hs code - The poop on composting case study answers - In a team structure ________ - Creating a Resource List - Myhealth va gov sign in - Why can't aldehydes hydrogen bond - Cpni hostile vehicle mitigation - Operational definition of customer satisfaction - Lord of the flies piggy - Assignment - Professional Contribution Comments/Replies - Why we work by andrew curry essay - So what's so bad about being so so summary - Define boiling point in chemistry - Lit Review - Essay #2 (Food Analysis) - Bus katoomba to echo point - Write the economic analysis section of a business proposal - Functional level strategy is formulated by - Work study time study - Workshop flyer - A beautiful mind speech - Question - MKTG201 Week 6 Assignment 6.docx - Different biomes in canada - Accurate answers to the questions demonstrating knowledge of statutory interpretation - Hamlet's blackberry chapter 11 summary - 4 page essay - Living philosophy by lewis vaughn pdf - Headings for a report - What the ceo wants you to know ppt - Computer Related Crime - Shoebox diorama book report instructions - Apply: Signature Assignment: Shareholder Analysis - Palo alto custom report examples - The lorax worksheet environmental science - Group 16 period 3 - Wireshark filter probe request - Uncle tobys oats aldi - History class homework - Duke of wellington wareham - The internal external ie matrix - Fdi dental numbering system - Cafr analysis project - How to scale a log board feet - Wk 2, HCS 341: Legal, Safety, and Regulatory Requirements Paper - Develop PPT slides about Risk Management - Belajar photoshop cs3 pdf - Widgets r us uses a variety - Greek mythology family tree - Www joboutlook gov au - All it takes is for good man to do nothing - Othello tragic hero essay - Samsung robot vacuum error code c05 - Chemical reaction lesson plan - Compute chavez company's current ratio using the above information - Holley electric fuel pump pressure regulator - HTML & css , etc. website creation - Bellamy is a private corporation and is presenting comparative financial statements. - Electrical separation shaver socket diagram - Ingredients in black salve - Rocket sled physics classroom worksheet answers - Compound interest problems worksheet - How has an understanding of consumer behavior helped coppertone - Mg hcl mgcl2 h2 balanced - South coast powder coating - Chemistry notes year 12 - COPD case study - Power drive corporation designs and produces - Evidence-Based Project - Anthony kevin dungy - Curveball the year i lost my grip sparknotes - Fronius primo wifi setup - Firo b test questions pdf - Excel 2016 capstone project ex 1 working with sales data - Oxford islamiyat book 2 teaching guide in english - Human Ecology - "A" WORK PLAGIARISM FREE - Help with Final assignment - Data Leakage Research Paper - Delta fig 55 ball valve - The common denominators of luxury brands are quality and - Australian curriculum economics and business - NEED IN 18 HOURS or LESS - David hockney paint trolley - Pooled standard deviation calculator excel - The world of art book pleasantville - In a laboratory experiment you wish to determine the initial speed of a dart - Something good robert munsch - Open root pipe welding - North norfolk council housing - Ohp 1 rep max calculator - Acc 202 presentation to investors - Silver nitrate and sodium hydroxide - What is rehashing in data structure