Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
Related questions
Question
I know it's a lot, but I would really appreciate some help!
![Story
base
Students were asked to perform a lab to identify an unknown acid.
The experiment has several parts.
First the students had to make a sodium hydroxide solution with a molarity of approximately 0.2M.
Then the students had to perform a titration with potassium hydrogen phthalate to standardize their
solution.
Finally they had to perform a titration with the unknown acid to find the pKa and the molar mass, then
using their data they had to determine which of the weak acids they had used.
Part 1) Make a sodium hydroxide solution
A student measured 4.03 grams of NaOH in a tared weigh boat. They then dissolved it into approximately 200 mL
of deionized water in a beaker. Once it was completely dissolved the student poured the solution into a 500.0 mL
volumetric flask. The student rinsed the beaker with deionized water and added the rinse water to the volumetric
flask. They repeated with process, adding the rinse water to the volumetric flask again, they mixed this thoroughly.
Finally, they filled the volumetric flask with distilled water, mixing and then waited for the solution to reach room
temperature before topping off the solution.
A) Calculate the theoretical molarity of the NaOH solution.
M = mol
Nuot
4.03g
X
1 ml NaOll
Nabit
39.9985
Part 2) Standardize the NaOH solution.
NaOH is a hygroscopic solid, which means that it can absorb water from its surroundings, therefore it is important
to determine the actual concentration of the sodium hydroxide solution. To do this the sodium hydroxide solution
is titrated with potassium hydrogen phthalate, (KHC8H404, Molar mass = 204.23g/mol). KHP is a stable
monoprotic solid acid. 1.04 grams of potassium hydrogen phthalate was dissolved into 100.0 mL of water, 2 drops
of indicator was added. This was then titrated with the sodium hydroxide solution that was made in part 1. The
initial reading of the buret was 1.23 mL and at the equivalence point in the titration 28.74 mL was the reading on
the base buret.
0.100755 rol Nooit
NaOH(aq) + KHC8H404 (aq) NaKC8H404(aq) + H₂O
OH(aq) + HC8H404°(aq) ⇒ C8H404² (aq) + H₂O)
B) How many moles of KHP were used?
C) What volume of NaOH was needed?
D) What it the molarity of the standardized NaOH solution?
L
netges od
08 (8
Part 3) Determine the identity of a unknown solid
The standardized solution of NaOH was then used to determine the identity of an unknown acid. 0.785 grams of
the unknown monoprotic acid was titrated using 23.55 mL of the sodium hydroxide solution. The graph below was
created.
HA(aq) + OH(aq) = H₂O + A (aq)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F2c689efc-1d04-4526-a0aa-c90055c9f29f%2F711ce1cd-5047-4e3c-86d8-f4e4f3700b7e%2Fpjoiwe_processed.png&w=3840&q=75)
Transcribed Image Text:Story
base
Students were asked to perform a lab to identify an unknown acid.
The experiment has several parts.
First the students had to make a sodium hydroxide solution with a molarity of approximately 0.2M.
Then the students had to perform a titration with potassium hydrogen phthalate to standardize their
solution.
Finally they had to perform a titration with the unknown acid to find the pKa and the molar mass, then
using their data they had to determine which of the weak acids they had used.
Part 1) Make a sodium hydroxide solution
A student measured 4.03 grams of NaOH in a tared weigh boat. They then dissolved it into approximately 200 mL
of deionized water in a beaker. Once it was completely dissolved the student poured the solution into a 500.0 mL
volumetric flask. The student rinsed the beaker with deionized water and added the rinse water to the volumetric
flask. They repeated with process, adding the rinse water to the volumetric flask again, they mixed this thoroughly.
Finally, they filled the volumetric flask with distilled water, mixing and then waited for the solution to reach room
temperature before topping off the solution.
A) Calculate the theoretical molarity of the NaOH solution.
M = mol
Nuot
4.03g
X
1 ml NaOll
Nabit
39.9985
Part 2) Standardize the NaOH solution.
NaOH is a hygroscopic solid, which means that it can absorb water from its surroundings, therefore it is important
to determine the actual concentration of the sodium hydroxide solution. To do this the sodium hydroxide solution
is titrated with potassium hydrogen phthalate, (KHC8H404, Molar mass = 204.23g/mol). KHP is a stable
monoprotic solid acid. 1.04 grams of potassium hydrogen phthalate was dissolved into 100.0 mL of water, 2 drops
of indicator was added. This was then titrated with the sodium hydroxide solution that was made in part 1. The
initial reading of the buret was 1.23 mL and at the equivalence point in the titration 28.74 mL was the reading on
the base buret.
0.100755 rol Nooit
NaOH(aq) + KHC8H404 (aq) NaKC8H404(aq) + H₂O
OH(aq) + HC8H404°(aq) ⇒ C8H404² (aq) + H₂O)
B) How many moles of KHP were used?
C) What volume of NaOH was needed?
D) What it the molarity of the standardized NaOH solution?
L
netges od
08 (8
Part 3) Determine the identity of a unknown solid
The standardized solution of NaOH was then used to determine the identity of an unknown acid. 0.785 grams of
the unknown monoprotic acid was titrated using 23.55 mL of the sodium hydroxide solution. The graph below was
created.
HA(aq) + OH(aq) = H₂O + A (aq)
Expert Solution
![](/static/compass_v2/shared-icons/check-mark.png)
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
This is a popular solution!
Trending now
This is a popular solution!
Step by step
Solved in 6 steps
![Blurred answer](/static/compass_v2/solution-images/blurred-answer.jpg)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.Recommended textbooks for you
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781305957404/9781305957404_smallCoverImage.gif)
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781259911156/9781259911156_smallCoverImage.gif)
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
![Principles of Instrumental Analysis](https://www.bartleby.com/isbn_cover_images/9781305577213/9781305577213_smallCoverImage.gif)
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781305957404/9781305957404_smallCoverImage.gif)
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781259911156/9781259911156_smallCoverImage.gif)
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
![Principles of Instrumental Analysis](https://www.bartleby.com/isbn_cover_images/9781305577213/9781305577213_smallCoverImage.gif)
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
![Organic Chemistry](https://www.bartleby.com/isbn_cover_images/9780078021558/9780078021558_smallCoverImage.gif)
Organic Chemistry
Chemistry
ISBN:
9780078021558
Author:
Janice Gorzynski Smith Dr.
Publisher:
McGraw-Hill Education
![Chemistry: Principles and Reactions](https://www.bartleby.com/isbn_cover_images/9781305079373/9781305079373_smallCoverImage.gif)
Chemistry: Principles and Reactions
Chemistry
ISBN:
9781305079373
Author:
William L. Masterton, Cecile N. Hurley
Publisher:
Cengage Learning
![Elementary Principles of Chemical Processes, Bind…](https://www.bartleby.com/isbn_cover_images/9781118431221/9781118431221_smallCoverImage.gif)
Elementary Principles of Chemical Processes, Bind…
Chemistry
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY