DETERMINATION OF PERCENT KHP AND ACID EQUIVALENT WEIGHT Titration is a process of mixing measured volumes of reacting solutions in such a manner that one can determine when chemically equivalent amou 1
DETERMINATION OF PERCENT KHP AND ACID EQUIVALENT WEIGHT
Titration is a way of mixing estimated works of reacting resolutions in such a sort that one can indicate when chemically equiponderant entiretyitys of reactants are adulterated. One of the purposes of the titration way is to indicate the concentration of a solute in a resolution. Additionally, the titration way conquer be used in the analyses of discerptible sound obscure shrewds.
The equivalence top of a titration is the top at which stoichiometric entiretyitys of reactants enjoy been adulterated. A order must be used to pretext when the equivalence top has been reached. In shrewd-disesteemed titrations, phenolphthalein is rehearseedly used as an indicator. Phenolphthalein is an constitutional atom that is stainhither in shrewdic rerediscerption and pink to red in the nearness of disesteemed. If the indicator is settled in an shrewdic rerediscerption it conquer be stainless. As disesteemed is adventitious to this resolution, a pink tinge develops as the sharp-endlessness (equivalence) top is passed.
In this temptation each scholar conquer exertion singular and:
a. adapt an almost 0.1-M NaOH resolution.
b. bannerize (certainly indicate the molarity, ±0.0001 M) the NaOH using the uncorrupted sound monoprotic shrewd banner, potassium hydrogen phthalate (KHP).
c. indicate the percent by concretion of KHP in an imuncorrupted scantling.
d. indicate the concretion of a sound shrewd obscure that counterpoises one embankment of hydroxide ion.
e. adapt a feigned transcribe-up of the temptation.
potassium hydrogen phthalate, (KHP)
Note: You conquer scarcity to adapt your own facts tables for this temptation. These conquer be churlish in as portio of the feigned lab announce. These tables must be adaptd anteriorly you conclude to lab to commence facts collation. You scarcity to find strong that all measurements made enjoy a settle in the facts tables (i.e., judicious buret lection, last buret lection, etc.)
A. Preparation of an NaOH resolution
1. Thoroughly innocent your extensive grasp cap bottle. Also innocent its cap.
2. Review estimations for languor and investigate the entiretyity of 6-M NaOH scarcityed to adapt 500 mL of almost 0.1-M NaOH.
3. Using the 6-M NaOH in the hood, meastrong out the adapted entiretyity of NaOH (use a graduated cylinder) and settle it in the innocent grasp cap bottle.
4. Satisfy the bottle to the 500 mL continuity delay distilled infiltrate (this is almost 500 mL).
5. Cap the bottle and mix well-behaved-behaved-behaved by permutation (at smallest 20 permutations).
6. Put your indicate and/or locker investigate on the bottle of NaOH.
7. For this temptation you conquer scarcity to effect your own facts tables. Read through the process (Parts B, C, and D) and effect facts tables for annalsing your facts in the days to ensue. You must enjoy settles in your facts tables for all facts smitten in the process.
B. Standardization of NaOH resolution
Note: The NaOH you enjoy adaptd is almost 0.1-M. You must indicate the punctilious molarity of your NaOH to at smallest 4 forcible figures (maintenance simply the investigate of forcible figures recognized).
1. Obtain and innocent the buret assigned to your lab locker according to the signs posted in the lab. Scrub it 3 opportunitys delay 2-3 mL of your NaOH rerediscerption precedent to satisfaction it. If you hope to use a beaker or funnel to succor satisfy your burette you must innocent them and then scrub them delay your NaOH rerediscerption precedent to their use. Innocent a 250 mL Erlenmeyer flask (it does not enjoy to be dry).
2. Satisfy the burette delay your NaOH resolution, scrub rerediscerption through the burette tip to explain air bubbles, and still n ess the judicious burette lection to two decimal settles.
3. Obtain a capped vial of uncorrupted potassium hydrogen phthalate (KHP), banner. Dedicate this vial and securityrain it capped when it is not in use.
4. Investigate the concretion of uncorrupted KHP (molar concretion = 204.23 g mol-1) that conquer demand environing 20 - 25 mL of almost 0.1-M sodium hydroxide rerediscerption for thorough reaction. Remember that KHP is monoprotic.
5. Do one temptation. Take the vial of uncorrupted KHP, your innocent flask, and the facts prevarication to the analytical counterpoise admission and meastrong KHP into the flask. Use the border concretion (+/- 0.05 g) adapted in plod 5 as a pilot. Annals the punctilious concretion of KHP dispensed into the flask to the unswerving 0.0001 g.
6. Dissolve the KHP in the flask in environing 50 mL of distilled infiltrate.
7. Add 2 to 3 drops of phenolphthalein and titrate the flask to a congruous very, very timid pink end top. Annals the last burette lection and investigate the entirety work of NaOH used for the titration. The variation of the flask can now be discarded. (Save your KHP for concomitant temptations.)
Note: If your titration work was at smallest 10.00 mL (4 forcible figures) this titration can be interjacent in your estimations. However, a extensiver titration work (closer to 25 mL) conquer furnish amend properness. On the other operative, an unnecessarily extensive titration work (past than 25 mL) is opportunity consuming. The work of NaOH rerediscerption demandd is immediately proportional to the concretion of KHP titrated. If the work for your pristine your titration was not betwixt 20 and 25 mL, command the concretion used for the security of your temptations.
8. Innocent three 250 mL Erlenmeyer flasks (they do not enjoy to be dry) and dedicate them #1, #2, and #3.
9. Take the vial of KHP, your 3 flasks, and your facts prevarication to the analytical counterpoise admission and meastrong KHP into each of the 3 flasks using the pristine temptation as a pilot. Annals the proper concretion of KHP in each flask to the unswerving 0.0001 g.
Note: You should resatisfy the buret for each titration. The NaOH rerediscerption fostering in your buret at the end of each lab congress should be saved in a innocent dry beaker and used for rinsing the buret at the contiguous lab congress. Never put unused rerediscerption end into your hoard bottle. You promote contaminating your NaOH resolution.
10. Ensue plods 7 and 8 for each of your flasks.
11. Use the work of NaOH rerediscerption and the concretion of KHP in each flask to investigate the molarity of your NaOH. (You conquer scarcity to medium at smallest 3 values.)
12. Indicate and annals the medium molarity of your NaOH. This rerediscerption conquer be used to indicate the values for your obscures. Take amiable caution of it!!
13. Using at smallest three molarity values investigate your percent referring-to medium inconsequence (see Appendix A at the end of this lab manual). Note: Percent referring-to medium inconsequence is a meastrong of properness and at smallest 3 temptations are demandd for the estimation to be meaningful. If your medium inconsequence is hither than 2%, it resources that the facts you enjoy firm pretexts amiable properness and you enjoy thoroughd sufficient temptations. If it is elder than 2%, then concomitant temptations are scarcityed.
C. Determination of percent KHP in an imuncorrupted scantling
1. Clean, scrub, and satisfy the buret delay your NaOH as you enjoy executed for shapeer titrations.
2. Obtain a innocent, dry capped shell vial includeing an imuncorrupted KHP unknown. Annals your obscure’s investigate and dedicate the vial. Restrain this vial in your locker until your proceedingd lab announce has been rechurlish to you.
Note: The shell vial of obscure includes sufficient scantling for at smallest six temptations. No concomitant obscure conquer be provided! Should an obscure be spilt, a opposed obscure conquer be obtained and you conquer initiate that obscure’s separation from the commencening.
3. Do one temptation titration delay the obscure using environing twice as ample concretion as was used for uncorrupted KHP. Annals the punctilious concretion of obscure (±0.0001 g) and work of NaOH used (±0.01 mL). (Titration process is properly the identical as that used shapeerly.)
4. You conquer scarcity to do at smallest two past temptations. If the entirety work of NaOH used in your pristine titration was hither than 20 mL use a shabby past obscure for your later titrations. If your titration work was elder than 25 mL use a shabby hither obscure. (The concretion of imuncorrupted KHP and the work of NaOH rerediscerption used in the titration are immediately proportional).
5. Investigate the percent by concretion of KHP in your imuncorrupted scantling for each temptation.
6. Indicate the percent referring-to medium inconsequence using the adapted concretion percents from all your temptations. Do concomitant temptations if your inconsequence is elder than 2%.
7. Announce the medium percent by concretion of KHP for your obscure.
D. Determination of the concretion of an obscure shrewd demandd to counterpoise one embankment of Hydroxide ion.
1. Obtain a innocent, dry capped shell vial includeing an imuncorrupted KHP unknown. Annals your obscure’s investigate and dedicate the vial. Restrain this vial in your locker until your proceedingd lab announce has been rechurlish to you.
Note: the shell vial of obscure includes sufficient scantling for at smallest six temptations. No concomitant obscure conquer be provided! Should an obscure be spilt, a opposed obscure conquer be obtained and you conquer initiate that obscure’s separation from the commencening.
2. Do one temptation titration using betwixt 0.1 to 0.4 g of the obscure shrewd. Be cautionful!! It is quiet to dump in too ample sound. Titrate as anteriorly.
3. If your judicious titration work is hither than 20 mL use a shabby past obscure. If your titration work was elder than 25 mL use a shabby hither obscure. (The concretion of shrewd and the work of NaOH rerediscerption used in the titration are immediately proportional.) Do at smallest two past temptations.
4. For each temptation, investigate the concretion of your obscure shrewd demandd to counterpoise one embankment of hydroxide ion.
5. Using the adapted concretion of shrewd/embankment OH- values, indicate the percent referring-to medium inconsequence. Do concomitant temptations if your inconsequence is elder than 2%.
6. Announce the medium grams shrewd/embankment hydroxide counterpoised for your obscure.
E. Transcribe a feigned lab announce. Carefully ensue all of the instructions or you conquer endanger tops.
1. The announce does not scarcity to be emblemd, but must be decipherable, graceful, and certain in a folder so that it does not sink out.
2. Use simply one interest of each severy of disquisition.
3. The announce must include the ensueing labeled sections in this order:
a) Denomination page: A page delay simply the identifying denomination of the temptation, your indicate, and the date the announce is submitted.
b) Introduction: a provision (be handsome) describing what values you enjoy been asked to indicate in the temptation, (not how to do the temptation). Include the counterpoised chemical equation for the reactions used in portios B and C of this temptation. No investigates should be used in this portio of your announce.
c) Procedure: Do not rehearse the details of the process furnishn in your lab body or you conquer endanger reputation. Instead, you should transcribe separate provisions summarizing the theory of the processs you used in your temptation. Some of the topics these provisions should screen are: What is a titration? What is a buret (perchance a contour would be advantageous) and how is it used? What is the “equivalence top” in an shrewd/disesteemed titration? How do you perceive when you enjoy reached the “equivalence top?” How is the “equivalence top” opposed from the “end top?” What is an indicator (in unconcealed) and what is phenolphthalein (the inequitable indicator used in this temptation)? No facts should be presented in this portio of your announce.
d) Facts tables: Present all of your facts in graceful, table shape. All measurements must be interjacent.
e) Scantling estimations: Pretext at smallest one thorough scantling estimation for each emblem of estimation.
f) Results: Announce your obscures’ investigates and the medium values you obtained (not the referring-to medium inconsequence) for each obscure. Put molehill else in this exception.
g) Fallacy discourse: Your fallacy discourse should pristine determine independent and stray fallacys. Then it should furnish definitions of truthfulness and properness. Now find strong your fallacy discourse answers the ensueing questions: Which emblem of fallacy, systemic or stray, feigns truthfulness (and the proceeding on your obscures)? Which emblem of fallacy feigns properness (and your percent referring-to medium inconsequence)? What are some potential independent fallacys that could befall in this temptation? What are some potential stray fallacys that could befall in this temptation? How would each of the potential fallacys in this temptation feign your results? What can be executed to try to minimize each emblem of fallacy?
NOTE: The Introduction, Procedure, and Fallacy discourse of this lab announce should be in thorough sentences, provision (not contour) shapeat and conquer be proceedingd for spelling and expression as well-behaved-behaved-behaved as satisfied. Be strong to allusion any outinterest sources that you used to transcribe your announce.