Abstract of Identification of an unknown acid by titration

In order to identify, the concentration of KHP (Potassium hydrogen Phthalate) in an unknown sample this experiment was performed. By first synthesizing a sodium hydroxide solution this task was accomplished as well as to determine the molarity of the solution by using titration analysis. 0.1 molar was the target molarity as well as average molarity is calculated by the synthesized solution was 0.1035M0.0001530M with precise result of titration. To identify the percentage of Potassium hydrogen Phthalate is unknown the same titration method is used. With a standard deviation of 0.1000 which was determined to be 34.60%. that is depend on the variation of percent 0.2900% as well as accuracy check of 0.2300% by the instructor, precise result as well as relative accurate are supported.

Introduction of Identification of an unknown acid by titration

Acidity of solution is determining as well as compounds is a main part of certain disciplines, for example quality control labs industrial or else science of environmental. It is difficult to identify the proper acidity as well as compound’s purity along with for proper reagents “grading” in an industrial lab setting. The quality of a substance is determines by the grading, it will receive the advertisement, as well as it will be most applicable inside which the field will be most applicable. Such as, for analytical application the product that is more important is analytical purpose, quality control, as well as researchers of other types; while a Pharmacopoeia Grade product is of higher quality as well as in pharmaceutical settings are used. In the environment finding the acidity could be particularly vital when dealing with various organisms, plants, as well as populations. If, for instance, the water of a lake is found to be acidic, try to reverse the pH level this is very important before on the ecosystem it has a detrimental toll (LCRA, 2011).

To define the endpoints of a reaction a titration method is used to analyze, as a result in the reaction determine the exact quality of reactant. To deliver a reactant a buret is used to the solution, while to retain a constant mixture a stir bar as well astir plate within the solution. To determine precise endpoint of the reaction frequently with a color changing reaction or else pH meter is used, a chemical indicator. By recording the initial volume of the reactant the quantity of the reactant could be found in the buret as well as the final volume subtracting. KHP (Potassium acid phthalate) as a primary standard it’s frequently used because it is stable chemically, in expensive, soluble in water, as well as in high purity quantities it can be obtained.

204.22 Daltons it has a formula weight, 1 mole of H+ is equivalent too, in neutralization titrations excellent choice as well as make it stable. To obtain a pure sample it is more difficult of sodium hydroxide because of the extensive process that should be completed. NaOH in order to obtain a pure sample free of carbonate contaminates that is used for “boil off” from liquid nitrogen as well as by carbon dioxide free water boil it. Heat of reaction as well as too exothermic dilution are hard to keep under control, as well as in solid form also have the remnants left (Milde, 2011).

To the bases the protons from the acid are transferred, in acid-base reaction in the following example;

To the base sodium hydroxide its available proton as the hyaluronic acid transfers, in the end product of water and salt it readily reacts resulting. In this neutralizing titration a similar reaction occur; with the sodium hydroxide as the potassium acid phthalate, as you can see in the following equation water as well as potassium sodium phthalate are produced;

There is no obvious color change, in most acid-base reaction; an indicator is used which will mostly use for the change of color. To determine accurately the endpoint of the reaction for this experiment phenolphthalein was used. The phenolphthalein is colorless in an acidic solution, it expresses a pink color in a basic solution. Moreover, once the basic solution is reached the solution will change color, between the KHP along with the NaOH entailing the precise endpoint of the reaction (Swensons, 2005).

Experimental Methods of Identification of an unknown acid by titration

For the preparation of 0.1 M NaOH solution, 0.1M NaOH ‘s 500mL was prepared for a required quantity of 6.0 M NaOH . Into a plastic bottle of 500mL, this quantity was added until the gain of needed volume. NaOH’s final morality was determined with the use of Titration. With the measurement of KHP or Potassium Hydrogen Phthalate’s pre-dried four samples, this accomplishment of this task took place. Masses ranged from 0.5g-0.7g while samples were transferred to Erlenmeyer four flasks. Later on, a consecutive order took place with the addition endpoint indicator phenolphthalein 3 drops and deionized water 3 drops were added to each and every sample.

KHP’s smallest amounts were added with NaOH using titration until a hue of pink appeared for a longer duration with the utilization of NaOH’s half-drops as required. The sides of flask needed to be washed for the addition of NaOH once the change in color was detected for measuring accurately. With the use of NaOH, the first neutralization in titrations was obtained with the same volume as the previous one for an initial point on the basis of amount of NaOH in the solution which is proceeding. NaOH’s final molarity was measured with the use of standard deviation and average morality of the trio of nearest subjects.

For the determination of KHP in a mixture which is unknown, 4 samples among 0.5g-0.7g were consecutively ordered after weighing them to largest from smallest. Into clean flasks, 4 samples were sent with deionized water’s 50mL and indicator phenolphthalein’s 3 drops were added. For the identification of KHP, titration procedures were almost the same for the determination of synthesized NaOH solution’s molarity. The data which was obtained from three titrations which were the best, KHP’s percentage was measured in an unknown sample.

Results of Identification of an unknown acid 

Table 1. Sodium hydroxide standardization

Table 2. Sodium hydroxide standardization result

Table 3. Unknown Sample of KHP titration

Table 4. Results of Unknown Sample of KHP titration

Sample calculation of Identification of an unknown acid by titration

-KHP moles

Sample mass* 1 mole/molar mass

Ex. 0.5047g* 1mole/204.22g= 0.002471 mol KHP

Volume of NaOH used

Final volume –initial volume

Ex. 24.10mL – 0.25mL=23.85mL

-Molarity

Moles/L

Ex. 0.002471 mol/0.02385L

=0.1036 mol/L

In sample KHP percent

(Mass of sample/grams used)*100

Ex. (0.184g/0.000903g) * 100

=34.6%

Average

Total/ number of total inputs

Ex. 34.6%+34.5%+34.7%)/3

34.60%

Standard Deviation

√∑ ( KHP average percent- actual yield)2/2

Ex. √ (34.6-35.6) 2 + (34.6- 34.5) 2 + (34.6- 34.7)2 = 0.10

Percent Variation

(Standard Deviation / Average Percent KHP ) * 100

Ex. 0.10 / 34.6) * 100 = 0.29%

Discussion & results of Identification of an unknown acid by titration

0.1035 M ± 0.000153 M was the synthesized solution’s final concentration for standardizing the aqueous sodium hydroxide as per the titration. 0.1 M was the target molarity. So, we were quite near to solution molarity whichw as required. Table 2 supported the conclusion of 0.1478 percent was the solution’s percent variation. The determination of KHP percent was possible with synthesized NaOH solution’s molarity in a sample which was unknown #36 to be 34.60%. Our findings are supported by 0.2900% percent variation so did the check for accuracy of our professor while 0.2300% was the amount (Table 4).

Sodium hydroxide’s titrations were quite accurate and precise especially regarding the ones with trial 3, trial 2, and trial 1 (Table 1). KHP’s titrations were also clearer and specifically those of trial 3, trial 2, and trial 1 (Table 3). KHP concentration’s determination in the sample which was not known was quite authentic. 0.2900% percent variation is helpful for our findings so did the findings of our professor while 0.2300% was the value (Table 4). 

Sure, results were quite good and all, there were definitely some points here and there which could be improved with more accuracy. First of all, KHP samples’ measurement which were more authentic and similar. Such a method would have produced good results. Secondly, precision and accuracy could be better with titration method’s more practice. Overall, there might be some impurities or contaminations that could have caused a disruption between the actual values and our values. Here the below figure show the result of given trial.

References of Identification of an unknown acid by titration

LCRA. (2011, August 15). Lower colorado river autyority. Retrieved from http://www.lcra.org/water/quality/crwn/indicators.html

Milde. (2011, september 20). chemlab-titration. Retrieved from http://www.dartmouth.edu/~chemlab/techniques/titration.html

Swensons, J. (2005, january 2). Titration callibration and NaOH and KOH. Retrieved from http://www.newton.dep.anl.gov/askasci/chem03/chem03525.htm