ACID BASE TITRATION

I. Title of Experiment : Acid base titrationII. Day/Date Experiment : Wednesday/December, 11th 2013III. Experiments Done : Wednesday/December, 11th 2013IV. The Aim of Experiment : 1. Determining concentration of NaOH with standart solution oscalat acid.2. Determining concentration of HCl with NaOH solution.V. Supporting TheoreticalTitration is analysis way of measuring the amount of solvent is required to act consistently with the substance is contained in the other solution. Analysis is related to the volume of reagent solution is called volumetric analysis. Acid base titration is a quantitative analysis to determine the morality of acid or base. Substance is determined the morality is titrated with a solution that knowed the morality and with the addition of appropriate indicators. Function of indicator is to know the final point of titration. If indicator that used is right, the indicator will change the colour in final point of titration. Final point of titrarion is happen near the equivalent point of titration, that condision when acid solution right react with base solution.A suitable indicator should be chosen, preferably one that will experience a change in colour (an end point) close to the equivalence point of the reaction. Here is some data of indicator that may suit to the special reaction.

Principles of acid-base titration :Acid base titration involving acid or base as titer or titrant. Acid base titration based neutralization reaction. Level of acid solution was determined using base solution and vice velsa. Titrant is added titer gradually until reach equivalent condision (stoichiometrily titrant and titer right completely react). This condision is called equivalent paint. At this point, titration process is stopped, then we record the volume of titer that required to reach that conditian. Using data volume of titrant, volume and consentration of titer, so we can calculated titrant level.Method to know the equivalent point :1. Wearing pH meter to monitor pH change during titration is done, then make plot between pH with titrant volume to get titration airve. The midpoint of titration curve is equivalent paint.2. Wearing acid and bae indicator. Indicator is added to titraint before titration prosses is done. This indicator will change colour when equivalent paint is accur. At this momet, we can stop the titration. Selection of appropriate indicator is the main requirement of tiration. If indicator that used is change colour when equivalent paint, so final paint of titration will same with equivalent paint. But, if the colour change indicator is located in pH where nitrat agent is slight excess, so final paint of titration is differ with equivalent point. To state pH change when titration, is used titration curve. Titration curve is easy our to determine the equivalent paint.1. Strong acid and strong base 2. Strong acid and weak base

3. Weak acid and strong base 4. Weak acid and weak base

After we titrate the solution, we can know the concentration by the formula of: or

VI. Tools and MaterialsA. Tools1. Statif and klem2. Buret3. Erlenmeyer 250 mL4. Mumps pipette 25 mL5. Pipette6. Graduated cylinder7. Beaker glass 100 mL8. Funnel

B. Materials1. NaOH2. C2H2O43. HCl4. Phenopthalein5. Aquades6. Curcuma extract

VII. Procedure (Scheme of experiment)

IX. AnalysisAt the first experiment we determine for concentration of NaOH with 10 mL C2H2O4 0,05 M with Phenolphtalein as indicator. Before, the colour of NaOH, C2H2O4, phenolpthalein are colorless. After that, NaOH added into buret and dropped into erlenmeyer flask that contain 10 mL C2H2O4 0,05 M and 2 drops of phenolpthalein, the color of solution is changing slowly. After the certain volume of NaOH has been added, the solution changed in to pink (++++). It means the end titration has been occured. We repeated the experiment 3 times,we get V1=10 ml, V2=8 ml, and V3=7 ml. From this data, we get the average concentration of NaOH is 0,123 N.At the second experiment that is determining concentration of HCl 10 mL with NaOH whose concentration has been found from the first experiment with phenolphtalein as indicator. The initial color of HCl,NaOH and phenolpthalein before dissolved are colorless. After little by little NaOH in Buret are given to the HCl in Erlenmeyer flask that added 4 drops phenolphtalein, the color is changing slowly into pink (+). It means the end titration has been occurred. We repeated the experiment 3 times,we get V1=10,9 ml, V2=9,3 ml, and V3=8 ml.Based the data and use the formula, we get an average concentration of HCl is 0,115 N. At the third experiment it same as the second observing but we use natural indicator that is Curcuma Extract. The initial colour of NaOH and HCl are colorless. The colour of Curcuma extract is orange (+++).The HCl 10 mL in the Erlenmeyer flask added by 2 drops of Curcuma extract,the colour is yellow. After little by little NaOH in buret dropped into it, the color changing slowly until raise the certain volume of NaOH. The final color between NaOH + HCl (with Curcuma extract) is orange. We repeated this experiment 3 times, we get V1=9,8 ml and the colour is orange (++), V2=9,6ml and the colour is orange (++), and V3=9,3 ml and the colour is orange (+).

X. DiscussionIn the first experiment, the adding of NaOH is too much. The color changing is bright. We should repeat the experiment to get the exact data. But we dont. For the next two repeating, we do it well. The color changing is little, not too bright. So the titration process is end. Then about shaking the solution in Erlenmeyer, it also will make the color change and then state into certain color. So, the shaking of Erlenmeyer is influenced. The main is about washing of the tools. It also affects the experiment process. But, here we thoroughly wash it cleanly and also make dry by tissue. So the solution doesnt contaminate. Then about the other experiment, second and third, we try to conduct the experiment well. The color changing is suitable with theory, that for PP is pink, and for plant extract is transparent green. So, the problem here is less than the first experiment.

XI. Conclusion1. The concentration of NaOH is 0,100 N. The color changing is from colorless into pink. The indicator is phenolphthalein, so the pink color indicates base solution. Strong base (NaOH) plus weak acid (C2H2O4) is come into base solution.2. The concentration of HCl is 0,096 N. The color changing by PP is also pink, but in plant extract is red into green. It suitable with the theory we read. The character of solution here is come into neutral cause strong acid (HCl) plus strong base (NaOH) is neutral.

XII. Answer of Question1. Because the range pH of phenolphthalein is 8,3 10,0. And we know, that strong base (NaOH) titrate with weak acid (C2H2O4) the result will be base. So, we need base indicator here, thats phenolphthalein.2. Equivalent point is a point that the value of OH- and H+ is equal. The other word is when the pH of solution is neutral, but the end point is when the solution has changed its color. The changing is indicating that we have to end titration process.3. C2H2O4 as primary standard solutionNaOH as secondary standard solutionHCl as tertiary standard solution

XIII. ReferencesBrandy, J.E, dan Huminston. 1986. General Chemistry. John Wiley and Sans: Singapore.Briggs, J.R.G. 2002. Chemistry for GCE O level. Pearson Education Asis Pte, Ltd. Singapore.Chang, Raymond. 2005. Chemistry. Mc Graw-Hill: New York.Tim Kimia Dasar. 1993. Petunjuk Praktikum Kimia Dasar. Institut Teknologi Bandung: BandungTim Kimia Dasar. 2013. Petunjuk Praktikum Kimia Dasar. Surabaya: UNESAPress.

Surabaya, December 16th, 2013KnownStudentLecture/ Guidance Assistant

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ATTACHMENT

A. Prepare the tools 1. Put the buret into clam

1. Put the erlemeyer in bottom of burret .

B. Determine the concentration of NaOH solution using C2H2O4 solution 1. NaOH before titration

1. C2H2O4 before titration

1. Titration proces

1. C2H2O4 + phenoptalen after added NaOH

C. Determine the concentration of Hcl solution using NaOH solution

1. NaOH before titration

1. HCl before titration

1. Titration procces

1. HCl + phenoptalen after added NaOH

D. Determine natural indicator which has similar characteristic with phenoptalen .

1. Natural indicator (extract of curcuma)

1. NaOH

1. HCl + natural indicator.

1. HCL + natural indicator after added NaOH

Calculation1. Determine the concentration of NaOH solution using C2H2O4 solution 2NaOH + C2H2O4 Na2 C2O4 + 2H2Oa. V1 = Na.Va = Nb.Vb Nb = Mb x n Ma.n.Va = Mb.n.Vb= 0,098 x 1 0,05M. 2. 5.10-3 = Mb. 1. 5,1.10-3 = 0,098 N = Mb = Mb

b. V2 => Na.Va = Nb.VbNb = Mb x n Ma.n.Va = Mb.n.Vb = 0,102 x 1 0,05M. 2. 5.10-3 = Mb. 1. 4,9.10-3 = 0,102 N = Mb = Mb

c. V3 => Na.Va = Nb.VbNb = Mb x n Ma.n.Va = Mb.n.Vb = 0,100 x 1 0,05M. 2. 5.10-3 = Mb. 1. 5.10-3 = 0,100 N = Mb = Mb

Average Nb = = = 0,100 N

1. Determining HCl with NaOH which have been found the normalityIndicator : PP (phenolftalein)HCl H+ + Cl- N = ekivalenNaOH Na+ + OH- N. NaOH = 0,100 MVa, Na, Ma is for acidVb, Nb, Mb is for base

a. V1 => Na.Va = Nb.Vb Na . = 0,100 . Na= 0,098 N

b. V2 => Na.Va = Nb.Vb Na . = 0,100 . Na = 0,096 N

c. V3 => Na.Va = Nb.Vb Na . = 0,100 . Na = 0,096 N

Average Nb = = = 0,096 N