Skills Practice Titration With An Acid And A Base
BackLessonPrintNameClassDateSkills PracticeTitration with an Acid and a BaseTitration is a process in which you determine the concentration of a solutionby measuring what volume of that solution is needed to react completely witha standard solution of known volume and concentration. The process consistsof the gradual addition of the standard solution to a measured quantity of thesolution of unknown concentration until the number of moles of hydronium ion,H3O , equals the number of moles of hydroxide ion, OH . The point at whichequal numbers of moles of acid and base are present is known as the equivalencepoint. An indicator is used to signal when the equivalence point is reached. Thechosen indicator must change color at or very near the equivalence point. Thepoint at which an indicator changes color is called the end point of the titration.Phenolphthalein is an appropriate choice for this titration. In acidic solution,phenolphthalein is colorless, and in basic solution, it is pink.At the equivalence point, the number of moles of acid equals the number ofmoles of base.(1)moles of H3O moles of OH By definitionmoles(2) molarity (mol/L) (L)volumeIf you rearrange equation 2 in terms of moles, equation 3 is obtained.(3)moles molarity (mol/L) volume (L)When equations 1 and 3 are combined, you obtain the relationship that is thebasis for this experiment, assuming a one-to-one mole ratio and the units ofvolume are the same for both the acid and base.(4) molarity of acid volume of acid molarity of base volume of baseIn this experiment, you will be given a standard hydrochloric acid, HCl, solutionand told what its concentration is. You will carefully measure a volume of it anddetermine how much of the sodium hydroxide, NaOH, solution of unknown molarityis needed to neutralize the acid sample. Using the data you obtain and equation 4,you can calculate the molarity of the NaOH solution.OBJECTIVESUse burets to accurately measure volumes of solution.Recognize the end point of a titration.Describe the procedure for performing an acid-base titration.Determine the molarity of a base.Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A67Skills Practice Experiment
BackLessonPrintNameClassDateTitration with an Acid and a Base continuedMATERIALS 0.500 M HCl50 mL burets, 2100 mL beakers, 3125 mL Erlenmeyer flaskdouble buret clampNaOH solution of unknown molarityphenolphthalein indicatorring standwash bottle filled with deionizedwaterAlways wear safety goggles, gloves, and a lab apron to protectyour eyes and clothing. If you get a chemical in your eyes, immediately flush the chemical out at the eyewash station while calling to your teacher.Know the locations of the emergency lab shower and eyewash station and theprocedures for using them.Do not touch any chemicals. If you get a chemical on your skin or clothing,wash the chemical off at the sink while calling to your teacher. Make sureyou carefully read the labels and follow the precautions on all containers ofchemicals that you use. If there are no precautions stated on the label, ask yourteacher what precautions to follow. Do not taste any chemicals or items used inthe laboratory. Never return leftovers to their original container; take only smallamounts to avoid wasting supplies.Call your teacher in the event ofa spill. Spills should be cleaned uppromptly, according to your teacher’sdirections.Never put broken glass into aregular waste container. Brokenglass should be disposed of properly.0.00 mLHClburetNaOHburetProcedure1. Set up the apparatus as shown inFigure A. Label the burets NaOH andHCl. Label two beakers NaOH and HCl.Place approximately 80 mL of theappropriate solution into each beaker.2. Pour 5 mL of NaOH solution from thebeaker into the NaOH buret. Rinse thewalls of the buret thoroughly with thissolution. Allow the solution to drainthrough the stopcock into anotherbeaker and discard it. Rinse the burettwo more times in this manner, using anew 5 mL portion of NaOH solutioneach time. Discard all rinse solutions.Buretclamp50.00 mLRing standErlenmeyerflaskFigure ACopyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A68Skills Practice Experiment
BackLessonPrintNameClassDateTitration with an Acid and a Base continued3. Fill the buret with NaOH solution to above the zero mark. Withdraw enoughsolution to remove any air from the buret tip, and bring the liquid level downwithin the graduated region of the buret.4. Repeat steps 2 and 3 with the HCl buret, using HCl solution to rinse andfill it.5. For trial 1, record the initial reading of each buret, estimating to the nearest0.01 mL, in the Data Table. For consistent results, have your eyes level withthe top of the liquid each time you read the buret. Always read the scale at thebottom of the meniscus.6. Draw off about 10 mL of HCl solution into an Erlenmeyer flask. Add somedeionized water to the flask to increase the volume. Add one or two drops ofphenolphthalein solution as an indicator.7. Begin the titration by slowly adding NaOH from the buret to the Erlenmeyerflask while mixing the solution by swirling it, as shown in Figure B.Stop frequently, and wash down the inside surface of the flask, using yourwash bottle.BuretGround-glassstopcockJet tipSwirlingmotionof flaskFigure BCopyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A69Skills Practice Experiment
BackLessonPrintNameClassDateTitration with an Acid and a Base continued8. When the pink color of the solution begins to appear and linger at the point ofcontact with the base, add the base drop by drop, swirling the flask gentlyafter each addition. When the last drop added causes the pink color to remainthroughout the whole solution and the color does not disappear, stop thetitration. A white sheet of paper under the Erlenmeyer flask makes it easier todetect the color change.9. Add HCl solution dropwise just until the pink color disappears. Add NaOH again,dropwise, until the pink color remains. Go back and forth over the end pointseveral times until one drop of the basic solution just brings out a faint pinkcolor. Wash down the inside surface of the flask, and make dropwise addition ofNaOH, if necessary, to reestablish the faint pink color. Read the burets to thenearest 0.01 mL, and record these final readings in the Data Table.10. Discard the liquid in the flask, rinse the flask thoroughly with deionized water,and run a second and third trial.11. Record the known concentration of the standard HCl solution in the DataTable.DISPOSAL12. Clean all apparatus and your lab station. Return equipment to itsproper place. Dispose of chemicals and solutions in the containersdesignated by your teacher. Do not pour any chemicals down the drainor in the trash unless your teacher directs you to do so. Wash your handsthoroughly before you leave the lab and after all work is finished.Data TableBuret readings y of HClAnalysis1. Organizing Data Calculate the volumes of acid used in the three trials. Showyour calculations and record your results below.Trial 1: Volume of HCl Trial 2: Volume of HCl Trial 3: Volume of HCl Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A70Skills Practice Experiment
BackLessonPrintNameClassDateTitration with an Acid and a Base continued2. Organizing Data Calculate the volumes of base used in the three trials. Showyour calculations and record your results below.Trial 1: Volume of NaOH Trial 2: Volume of NaOH Trial 3: Volume of NaOH 3. Organizing Data Use equation 3 in the introduction to determine the numberof moles of acid used in each of the three trials. Show your calculations andrecord your results below.Trial 1: Moles of acid Trial 2: Moles of acid Trial 3: Moles of acid 4. Relating Ideas Write the balanced equation for the reaction between HCland NaOH.5. Organizing Ideas Use the mole ratio in the balanced equation and the molesof acid from Analysis item 3 to determine the number of moles of baseneutralized in each trial. Show your calculations and record your resultsbelow.Trial 1: Moles of acid Trial 2: Moles of acid Trial 3: Moles of acid 6. Organizing Data Use equation 2 in the introduction and the results ofAnalysis item 2 and 5 to calculate the molarity of the base for each trial.Show your calculations and record your results below.Trial 1: Molarity of NaOHTrial 2: Molarity of NaOHTrial 3: Molarity of NaOH7. Organizing Conclusions Calculate the average molarity of the base. Showyour calculations and record your result below.Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A71Skills Practice Experiment
BackLessonPrintNameClassDateTitration with an Acid and a Base continuedConclusions1. Analyzing Methods In step 6, you added deionized water to the HCl solutionin the Erlenmeyer flask before titrating. Why did the addition of the water notaffect the results?2. Analyzing Methods What characteristic of phenolphthalein made it appropriate to use in this titration? Could you have done the experiment without it?How does phenolphthalein’s end point relate to the equivalence point of thereaction?Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A72Skills Practice Experiment
BackLessonPrint PAGETEACHER RESOURCESkills PracticeTitration with an Acid and a BaseTeacher NotesTIME REQUIRED 60 minSKILLS ACQUIREDCollecting dataCommunicatingExperimentingIdentifying patternsInferringInterpretingOrganizing and analyzing dataRATINGTeacher Prep–3Student Set-Up–3Concept Level–3Clean Up–2Easy1234HardTHE SCIENTIFIC METHODMake Observations Students observe the color change at the end point of atitration.Analyze the Results Analysis questions 1 to 9Draw Conclusions Analysis question 7Communicate the Results Analysis questions 1 to 7MATERIALSTo prepare 1.0 L of 0.500 M hydrochloric acid, use a fresh bottle of reagent gradeconcentrated HCl, preferably one that shows the actual assay of HCl rather thanan average assay. Observe the required safety precautions. Assuming that theconcentrated HCl is 12 M, slowly and with stirring, add 41.65 mL to enough distilled water to make 1.00 L of solution. If a large number of students are to beprovided with solutions, it’s best to make up 10.0 L in a large dispenser to ensurethe same concentration for all lab groups. However, it will be impossible to makethe HCl exactly 0.500 M without the accuracy of a volumetric flask. Some 5 galcarboys with spigots make ideal dispensers for the acid and base solutions.To prepare 1.0 L of 0.6 M sodium hydroxide solution, observe the requiredsafety precautions. Stir while adding 24 g of NaOH to enough distilled water tomake 1.0 L of solution.To prepare 1.0 L of phenolphthalein solution, dissolve 10 g of phenolphthaleinin 500 mL of denatured alcohol and add 500 mL of water.A wet cloth mop can be rinsed out a few times and used until it falls apart.Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A67ATeacher’s Guide: Skills Practice Experiment
BackLessonPrint PAGETEACHER RESOURCETitration with an Acid and a Base continuedBromthymol blue may be used as an indicator and is the more appropriate indicator for the titration of a strong acid with a strong base. For the concentrationsof acid and base used, phenolphthalein and bromothymol blue give the samemolarity results.SAFETY CAUTIONSRead all safety precautions, and discuss them with your students. Safety goggles and a lab apron must be worn at all times. In case of an acid or base spill, first dilute with water. Then mop up the spillwith wet cloths or a wet cloth mop while wearing disposable plastic gloves.Designate separate cloths or mops for acid and base spills. Wear safety goggles, a face shield, impermeable gloves, and a lab apron whenyou prepare the NaOH and HCl solutions. For preparing HCl, work in a hoodknown to be in operating condition, and have another person stand by to callfor help in case of an emergency. Be sure you are within a 30 s walk from asafety shower and an eyewash station known to be in good operating condition.TIPS AND TRICKSDemonstrate all techniques needed for successful titration: cleaning the burets,reading the buret with the eye at the liquid level, reading the buret scale correctly,swirling the flask, manipulating the stopcock, washing down the sides of theflask, and evaluating the color of the indicator.Discuss the role of the indicator and the meaning of the terms end point andequivalence point. Indicators change colors at diffferent pH values. It is important to chose an indicator that changes color at a pH which is close to the pH ofthe equivalence point of the titration. For this titration, phenolphthalein is a goodindicator.It may help students if you work through a set of sample titration data.DISPOSALSet out three disposal containers for the students: one for unmixed acid solutions, one for unmixed base solutions, and one for partially neutralized substances and the contents of the waste beaker. To neutralize the acid and base,slowly combine the solutions while stirring. Adjust the pH of the final waste liquid with 1.0 M acid or base until the pH is between 5 and 9. Pour the neutralizedliquid down the drain.Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A67BTeacher’s Guide: Skills Practice Experiment
BackLessonPrint PAGETEACHER RESOURCENameClassDateSkills PracticeTitration with an Acid and a BaseTitration is a process in which you determine the concentration of a solutionby measuring what volume of that solution is needed to react completely witha standard solution of known volume and concentration. The process consistsof the gradual addition of the standard solution to a measured quantity of thesolution of unknown concentration until the number of moles of hydronium ion,H3O , equals the number of moles of hydroxide ion, OH . The point at whichequal numbers of moles of acid and base are present is known as the equivalencepoint. An indicator is used to signal when the equivalence point is reached. Thechosen indicator must change color at or very near the equivalence point. Thepoint at which an indicator changes color is called the end point of the titration.Phenolphthalein is an appropriate choice for this titration. In acidic solution,phenolphthalein is colorless, and in basic solution, it is pink.At the equivalence point, the number of moles of acid equals the number ofmoles of base.(1)moles of H3O moles of OH By definitionmoles(2) molarity (mol/L) (L)volumeIf you rearrange equation 2 in terms of moles, equation 3 is obtained.(3)moles molarity (mol/L) volume (L)When equations 1 and 3 are combined, you obtain the relationship that is thebasis for this experiment, assuming a one-to-one mole ratio and the units ofvolume are the same for both the acid and base.(4) molarity of acid volume of acid molarity of base volume of baseIn this experiment, you will be given a standard hydrochloric acid, HCl, solutionand told what its concentration is. You will carefully measure a volume of it anddetermine how much of the sodium hydroxide, NaOH, solution of unknown molarityis needed to neutralize the acid sample. Using the data you obtain and equation 4,you can calculate the molarity of the NaOH solution.OBJECTIVESUse burets to accurately measure volumes of solution.Recognize the end point of a titration.Describe the procedure for performing an acid-base titration.Determine the molarity of a base.Copyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A67Teacher’s Guide: Skills Practice Experiment
BackLessonPrint PAGETEACHER RESOURCENameClassDateTitration with an Acid and a Base continuedMATERIALS 0.500 M HCl50 mL burets, 2100 mL beakers, 3125 mL Erlenmeyer flaskdouble buret clampNaOH solution of unknown molarityphenolphthalein indicatorring standwash bottle filled with deionizedwaterAlways wear safety goggles, gloves, and a lab apron to protectyour eyes and clothing. If you get a chemical in your eyes, immediately flush the chemical out at the eyewash station while calling to your teacher.Know the locations of the emergency lab shower and eyewash station and theprocedures for using them.Do not touch any chemicals. If you get a chemical on your skin or clothing,wash the chemical off at the sink while calling to your teacher. Make sureyou carefully read the labels and follow the precautions on all containers ofchemicals that you use. If there are no precautions stated on the label, ask yourteacher what precautions to follow. Do not taste any chemicals or items used inthe laboratory. Never return leftovers to their original container; take only smallamounts to avoid wasting supplies.Call your teacher in the event ofa spill. Spills should be cleaned uppromptly, according to your teacher’sdirections.Never put broken glass into aregular waste container. Brokenglass should be disposed of properly.0.00 mLHClburetNaOHburetProcedure1. Set up the apparatus as shown inFigure A. Label the burets NaOH andHCl. Label two beakers NaOH and HCl.Place approximately 80 mL of theappropriate solution into each beaker.2. Pour 5 mL of NaOH solution from thebeaker into the NaOH buret. Rinse thewalls of the buret thoroughly with thissolution. Allow the solution to drainthrough the stopcock into anotherbeaker and discard it. Rinse the burettwo more times in this manner, using anew 5 mL portion of NaOH solutioneach time. Discard all rinse solutions.Buretclamp50.00 mLRing standErlenmeyerflaskFigure ACopyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A68Teacher’s Guide: Skills Practice Experiment
BackLessonPrint PAGETEACHER RESOURCENameClassDateTitration with an Acid and a Base continued3. Fill the buret with NaOH solution to above the zero mark. Withdraw enoughsolution to remove any air from the buret tip, and bring the liquid level downwithin the graduated region of the buret.4. Repeat steps 2 and 3 with the HCl buret, using HCl solution to rinse andfill it.5. For trial 1, record the initial reading of each buret, estimating to the nearest0.01 mL, in the Data Table. For consistent results, have your eyes level withthe top of the liquid each time you read the buret. Always read the scale at thebottom of the meniscus.6. Draw off about 10 mL of HCl solution into an Erlenmeyer flask. Add somedeionized water to the flask to increase the volume. Add one or two drops ofphenolphthalein solution as an indicator.7. Begin the titration by slowly adding NaOH from the buret to the Erlenmeyerflask while mixing the solution by swirling it, as shown in Figure B.Stop frequently, and wash down the inside surface of the flask, using yourwash bottle.BuretGround-glassstopcockJet tipSwirlingmotionof flaskFigure BCopyright by Holt, Rinehart and Winston. All rights reserved.Holt ChemFile A69Teacher’s Guide: Skills Practice Experiment
BackLessonPrint PAGETEACHER RESOURCENameClassDateTitration with an Acid and a Base continued8. When the pink color of the solution begins to appear and linger at the point ofcontact with the base, add the base drop by drop, swirling the flask gentlyafter each addition. When the last drop added causes the pink color to remainthroughout the whole solution and the color does not disappear, stop thetitration. A white sheet of paper under the Erlenmeyer flask makes it easier todetect the color change.9. Add HCl solution dropwise just until the pink color disappears. Add NaOH again,dropwise, until the pink color remains. Go back and forth over the end pointseveral times until one drop of the basic solution just brings out a faint pinkcolor. Wash down the inside surface of the flask, and make dropwise addition ofNaOH, if necessary, to reestablish the faint pink color. Read the burets to thenearest 0.01 mL, and record these final readings in the Data Table
point at which an indicator changes color is called the end point of the titration. Phenolphthalein is an appropriate choice for this titration. In acidic solution, phenolphthalein is colorless, and in basic solution, it is pink. At the equivalence point, the number of moles of acid equals the number of moles of base. (1) moles of H 3O moles of OH
What is redox titration? A TITRATION WHICH DEALS WITH A . REACTION INVOLVING OXIDATION AND . REDUCTION OF CERTAIN CHEMICAL . SPECIES. What is a titration? The act of adding standard solution in small quantities to the test solution till the reaction is complete is termed titration.
II. Weak acid- strong base titration In this part of the experiment you will do weak acid strong base titration. 0.05M, 20 mL CH 3 COOH is titrated with 0.05M NaOH. perform same procedure mentioned above. III. Mixture of weak acid, strong acid and strong base titration 0.02M, 10 mL HCl and 0.02M, 10 ml acetic acid mixture is titrated with 0.05 .
is that the visual method cannot be automated and is therefore difficult to validate and it lacks data integrity. This paper summarizes the steps involved in converting an existing manual titration procedure to semi-automated or automated titration procedures. It discusses topics such as selecting the right electrode and titration mode.
As in the weak acid-strong base titration, there are three major differences between this curve (in blue) and a strong base-strong acid one (in black): (Note that the strong base-strong acid titration curve is identical to the strong acid-strong base titration, but flipped vertically.) 1- The weak-acid solution has a lower initial pH.
Titration of amino acid: When an amino acid is dissolved in water it exists predominantly in the . isoelectric form. Amino acid is an . amphoteric. compound It act as either an acid or a base: Upon titration with acid it acts as a BASE (accept a proton). Upon titration with base it acts as an ACID (donate a proton)
Karl Fischer titration is the method of choice for water content determination. With the . with test certificate according to DIN 50049-2.3 First titrator (METTLER TOLEDO DL55) with online curves E f(t) and V f(t) for Karl Fischer titration. 1997 New DV705 KF Titration Stand with very low drift value ( 2μg/min) for the METTLER
Acid–Base Titration Experiment 7 Lecture and Lab Skills Emphasized Understanding the concept of titration. Explaining the difference between analyte and standard solutions. Know the definition of equivalence point. Converting between pH and the concentration of H . Calculating molarity.
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