Abstract:
In this experiment, examining the equivalence point in a titration with NaOH identified an
unknown diprotic acid. The molar mass of the unknown was found to be 100.78 g/mol with pKa
values of 2.6 and 6.6. The closest diprotic acid to this molar mass is malonic acid with a percent
error of 3.48%.
Introduction:
The purpose of the experiment was to determine the identity of an unknown diprotic acid. The
equivalence and half-equivalence points on the titration curve give important information, which
can then be used to calculate the molecular weight of the acid. The equivalence point is the
moment when there is an equal amount of acid and NaOH. Knowing the concentration and
volume of added NaOH at that moment, the amount of moles of NaOH can be determined. The
amount of moles of NaOH is then equivalent to the amount of acid present. Dividing the original
mass of the acid by the moles present gave the molar mass of the acid.
In this particular titration, there were two equivalence points as the acid is diprotic.
Consequently, the titration curve had two inflection points. The acid dissociated in a two-step
process with the net reaction being:
H2X + 2 NaOH Na2X + 2 H2O
This was important to take into consideration when calculating the molar mass of the diprotic
acid. If the first equivalence point was to be used, the ratio of acid to NaOH was 1:1. If the
second equivalence point was used in the calculations, the ratio became 1:2 as now a second
set of NaOH molecules reacted with the acid to dissociate the second hydrogen ion. The
titration curve also showed the pKa values of the acid. This happened at the half-equivalence
point where half of the acid was dissociated to its conjugate base (again, because of the diprotic
properties of the acid, this happens twice on the curve). The Henderson Hasselbalch equation
pH = pKa+log(A-/HA)
shows that at the half-equivalence point, the pKa value equaled the pH and was visually
represented by the flattest part of the graphs.
Discussion:
The titration graph showed that the data was consistent with the methodology and proved to be
an precise execution of the procedure and followed the expected shape. One possible source of
error was the actual mass of the acid solid. While transferring the dust from the weigh boat to
the solution, some remained in the weigh boat this could have altered the molar mass
calculations and shifted the final the final mass lighter than actual.
The Vernier pH method was definitely a much more concrete method of interpreting the results.
It was possible to see which addition of NaOH gave the greatest increase in pH ( greatest 1st
derivative of the titration graph). The relying solely on the indicator color would make it very
difficult to judge at which precise point the color shifted most, as the shift was a lot more gradual
compared to the precise numbers. This may have been a more reliable method if there was a
de.
Abstract In this experiment, examining the equivalence poi.docx
1. Abstract:
In this experiment, examining the equivalence point in a
titration with NaOH identified an
unknown diprotic acid. The molar mass of the unknown was
found to be 100.78 g/mol with pKa
values of 2.6 and 6.6. The closest diprotic acid to this molar
mass is malonic acid with a percent
error of 3.48%.
Introduction:
The purpose of the experiment was to determine the identity of
an unknown diprotic acid. The
equivalence and half-equivalence points on the titration curve
give important information, which
can then be used to calculate the molecular weight of the acid.
The equivalence point is the
moment when there is an equal amount of acid and NaOH.
Knowing the concentration and
volume of added NaOH at that moment, the amount of moles of
NaOH can be determined. The
amount of moles of NaOH is then equivalent to the amount of
acid present. Dividing the original
mass of the acid by the moles present gave the molar mass of
the acid.
In this particular titration, there were two equivalence points as
the acid is diprotic.
Consequently, the titration curve had two inflection points. The
acid dissociated in a two-step
process with the net reaction being:
H2X + 2 NaOH Na2X + 2 H2O
This was important to take into consideration when calculating
2. the molar mass of the diprotic
acid. If the first equivalence point was to be used, the ratio of
acid to NaOH was 1:1. If the
second equivalence point was used in the calculations, the ratio
became 1:2 as now a second
set of NaOH molecules reacted with the acid to dissociate the
second hydrogen ion. The
titration curve also showed the pKa values of the acid. This
happened at the half-equivalence
point where half of the acid was dissociated to its conjugate
base (again, because of the diprotic
properties of the acid, this happens twice on the curve). The
Henderson Hasselbalch equation
pH = pKa+log(A-/HA)
shows that at the half-equivalence point, the pKa value equaled
the pH and was visually
represented by the flattest part of the graphs.
Discussion:
The titration graph showed that the data was consistent with the
methodology and proved to be
an precise execution of the procedure and followed the expected
shape. One possible source of
error was the actual mass of the acid solid. While transferring
the dust from the weigh boat to
the solution, some remained in the weigh boat this could have
altered the molar mass
calculations and shifted the final the final mass lighter than
actual.
The Vernier pH method was definitely a much more concrete
method of interpreting the results.
It was possible to see which addition of NaOH gave the greatest
increase in pH ( greatest 1st
derivative of the titration graph). The relying solely on the
indicator color would make it very
3. difficult to judge at which precise point the color shifted most,
as the shift was a lot more gradual
compared to the precise numbers. This may have been a more
reliable method if there was a
device like a colorimeter to observe the precise wavelength of
the solution.
The unknown was most likely malonic acid as both the
calculated molar mass pKa values are
closest to it than the other diprotic acids. The judgment would
be questionable if molar mass
was the only indicator as the calculated mass may have been a
more severe skew of a different
diprotic acid. However, the pKa values confirmed that the
closest acid to the one identified is
malonic acid.
The color shifted from yellow to an almost clear color right
before it switched to blue. This
happened right around the equivalence point. That would make
the pKa value of Bromocresol
Green to be around 4.5. The pKa value of the other indictor was
somewhere around 9.5-9.7.
Discussion: Cooperative Training
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First Post—Module 3
A common form of training is cooperative training. There are
two widely used cooperative training methods: internships and
apprentice training. In both forms of training, there is a
4. combination of classroom training (formal education) and on-
the-job training (experience) that can be used for career
development. Based on your experiences, discuss the added
value of cooperative training. How do we as HRM professionals
objectively determine the "value" of cooperative training? Then,
discuss the problems of cooperative training that should be
taken into consideration by human resource professionals.
Finally, make a recommendation as to how cooperative training
can be assessed and used for succession planning.
Support your post with additional information from at least two
reputable sources (library and/or web-based). Cite your sources.
Bring in your own personal experiences, if applicable.
Module 3 – Background
Metrics & Analytics
For the past several years, HR has been all abuzz about metrics
and analytics. Everyone is talking about how to measure the
effectiveness of HR programs and assess their impact on
organizational outcomes. Well, what’s this talk all about? What
are metrics? What are analytics? What is benchmarking? How
are metrics, analytics, and benchmarking developed and used in
the HR context? Also, what are scoreboards and dashboards?
Answers to these questions will come from the reading and
research in this module.
Required Material
ASQ.org. (n.d.) What is a decision or Pugh matrix? Retrieved
from https://asq.org/quality-resources/decision-matrix.
Higgins, J. (2014). Bringing HR and finance together with
analytics. HR Magazine, 59(11), 44-46. Retrieved from
ProQuest in the Trident Online Library.
Lowisz, S. (July 2008). Six good metrics. Recruiting
Intelligence (ere.net). Retrieved from
http://www.ere.net/2008/07/07/6-good-metrics/.
Mahoney-Phillips, J., & Adams, A. (2010). Getting the measure
of HR. Strategic HR Review, 9(1), 5-9. Retrieved from
5. ABI/INFORM Global in the Trident Online Library.
Roberts. M. (Nov. 17, 2018). How hiring managers screen job
applicants. Retrieved from
https://www.thebalancecareers.com/how-do-hiring-managers-
screen-job-applications-1669574.
Shah, S.; Horne, A.; and Capella, J. (April 2012). Good data
won’t guarantee good decisions. Harvard Business Review.
Retrieved from https://hbr.org/2012/04/good-data-wont-
guarantee-good-decisions
Zielinski, D. (2014). Get analytical. HRMagazine, 59(11), 61-
62. Retrieved from ProQuest in the Trident Online Library.
Optional Material
Boyd, N., & Gessner, B. (2013) Human resource performance
metrics: methods and processes that demonstrate you care.
Cross Cultural Management 20.2 (2013): 251-273. Available in
the Trident Online Library.
Chhinzer, N., & Ghatehorde, G. (2009). Challenging
Relationships: HR Metrics and Organizational Financial
Performance. Journal Of Business Inquiry: Research, Education
& Application, 8(1), 37-48. Available in the Trident Online
Library.
Five steps to effective metrics. (2005). Strategic HR Review,
4(3), 7. Retrieved from ABI/INFORM Global in the Trident
Online Library.
Mirza, B. (2011). Cost-per-hire metric standard open for
comment. HR Magazine, 56(3), 80. Available in the Trident
Online Library.
Wroe, N. (2012). Innovations in Talent Analytics. T+D, 66(8),
30-31. Retrieved from the Trident Online Library.
360-Degree Feedback
Required Material
Custom Insight (2018). What is 360 Degree Feedback?
Retrieved from https://www.custominsight.com/360-degree-
feedback/what-is-360-degree-feedback.asp
Hudson Global (2018). What is 360 degree feedback? Retrieved
from https://www.youtube.com/watch?v=eT4tohLWeUw.
6. <br />
(Hudson Global, 2018)
Performance Experts (2017). 360 Degree Feedback. Retrieved
from https://www.youtube.com/watch?v=FDgtrg7k8Y4.
(Performance Experts, 2017)
Optional Material
Bracken, D. W., Rose, D. S., & Church, A. H. (2016). The
evolution and devolution of 360° feedback. Industrial and
Organizational Psychology, 9(4), 761-794. Retrieved from
ProQuest in the Trident Online Library.
Brett J, Atwater L. 360° Feedback: Accuracy, Accuracy,
Reactions, and Perceptions of Usefulness. Journal Of Applied
Psychology [serial online]. October 2001;86(5):930-942.
Available from: Business Source Complete in the Trident
Online Library
Nguyen, T., & Massingham, R. (2011). Using 360 degree peer
review to validate self-reporting in human capital measurement.
Journal of Intellectual Capital, 12(1), 143-74. Retrieved from
ProQuest in the Trident Online Library.
Internships/Apprenticeships
Required Material
10 Benefits of Starting an Internship Program. Retrieved from
http://www.internships.com/employer/resources/setup/benefits
The American Apprentice. (2013). HR Magazine, 58(11), 32-36.
Retrieved from ProQuest in the Trident Online Library.
Career and Professional Development Center (2016). Tips on a
successful internship, sponsored by General Electric. Retrieved
from https://www.youtube.com/watch?v=QHhV3_AxRLE.
Houston, L. (2014, Apr 23). Top law company hails benefits of
on-the-job training. Belfast Telegraph. Available in the Trident
Online Library.
Intern Queen Inc. (2016). How to run a successful internship
Program?|The Intern Queen. Retrieved from
https://www.youtube.com/watch?v=hnSqhSaLFW8.
7.
(Intern Queen, 2016)
Jones, D. A. (2011). Apprenticeships back to the future. Issues
in Science and Technology, 27(4), 51-56. Available in the
Trident Online Library.
Optional Material
10 Internship Characteristics that Attract Exceptional Interns.
Retrieved from
http://www.internships.com/employer/resources/setup/10-
internship-characteristics-that-attract-exceptional-interns
Apprenticeship. (1992). Occupational Outlook Quarterly, 35(4),
26. Retrieved from ProQuest in the Trident Online Library.
Blackhurst, J. (2013). Collaborative training. Training Journal,
9-12. Retrieved from the Trident Online Library
Google (2013). Google Interns’ first week. Retrieved from
https://www.youtube.com/watch?v=9No-FiEInLA.
>
(Google, 2013)
Lerman, R. I. (2011). In support of apprenticeships. Issues In
Science & Technology, 28(1), 12. Available in the Trident
Online Library.