One experimental flaw which resulted in readings inconsistent with the literature value was due to human error. Has two protons (diprotic) - need twice the amount of base as a monoprotic acid would need to be . The formula and structure for the carboxylic acid KHP is shown in Figure 5.1. Scholarship Chem. For Mastery on this assignment, you must Master 10 or more of these questions. The volumes of NaOH used up show significant fluctuations. The equivalence point is the mid-point on the vertical part of the curve. Now let's apply the molar ratio logic to obtain the moles Of OH-: .00278 moles of KHP means there's .00278 moles of H+, .00278 moles of H+ means the neutralized solution has.00278 moles of OH-. Why is neutralization a double replacement reaction? is a procedure used to compare the amount (moles) of acid in one sample with the amount (moles) of base in another. To standardize a sodium hydroxide (NaOH) solution against a primary standard acid [Potassium Hydrogen Phthalate (KHP)] using phenolphthalein as an indicator. Show your work. Nam lacinia pulvinar tortor nec facilisisonec aliquet. In this laboratory exercise you will carry out such a titration to. This will be a strong base - weak ac. Donec aliquet. . converted to moles of KHP used in the reaction, and then the grams of KHP present in the previously weighed sample can be determined. 2:314:57Processing Data from Titration of NaOH with KHP YouTubeYouTubeStart of suggested clipEnd of suggested clipWe have a one-to-one stoichiometric ratio that one mole of our standardized NaOH will be neutralizedMoreWe have a one-to-one stoichiometric ratio that one mole of our standardized NaOH will be neutralized for every one mole of the KHP. Number of moles of KHP in 2.00 grams = (m/M) = (2/204.22) mol = 0.00979 mol [c] KHP = n/V = (0.00979/0.1) mol dm -3 Number of moles of KHP in 0.01 dm 3 of solution in conical flask = [c] x V = 0.0979 x 0.01 = 9.79 x 10 -4 mol. 10. Lorem ipsum dolor sit amet, consectetur adipiscing elonec aliquet. This might have caused some deviations because the volume of sodium hydroxide added was excess. It is not hygroscopic. Related Textbook Solutions The example below demonstrates the technique to solve a titration problem for a titration of sulfuric acid with sodium hydroxide. Get a free answer to a quick problem. Show all of your work for each question. Use stoichiometry to determine moles of NaOH reacted. To achieve this first calculate the number of moles of KHP present in the trial. First you need to write out the balanced equation to determine the mole ratio between C8H5KO4. The molarity of the KHP solution is determined from the mass and volume of KHP used to prepare the KHP solution. 2) Determine the number of moles of KPH needed, and convert to grams First, we need to know the number of moles of NaOH we have. stream \[\text{moles solute} = \text{M} \times \text{L}\nonumber \]. Nam lacinia, iscing elit. The above equation can be used to solve for the molarity of the acid. Pellentesque dapibus efficitur laoreet. Lorem ipsum doec aliquet. KOOC COOH -c. CH C H i emochila m ohon FIGURE 5.1 Potassium hydrogen phthalate (KHC8H404) abbreviated as 'KHP KHP is available in high purity and is soluble in water. Write the balanced reaction between KHP and NaOH that occurs in this titration. Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. KHP is an acid with one acidic proton. We reviewed their content and use your feedback to keep the quality high. A link to the app was sent to your phone. Donec aliquet. The value of Ka from the titration is 4.6. Lorem ipsum dolor sit amet, consectetur adipiscing elit. \[\text{M}_A = \frac{\text{M}_B \times \text{V}_B}{\text{V}_A} = \frac{0.500 \: \text{M} \times 20.70 \: \text{mL}}{15.00 \: \text{mL}} = 0.690 \: \text{M}\nonumber \]. The difference between these sets of data indicates that the systematic error of allowing the KHP solution to become too pale resulted in strange fluctuations. Image transcription text11) KHCH404 (KHP) is a monoprotic acid commonly used to standardize aqueous solutions of 0.02965-0= 0 L This tells you that at you can reach the equivalence point by reacting equal number of moles of KHP and of NaOH . RAW DATA MASSES Trial #1 Trial #2 Trial #3 mass of KHP weighed out: 0.6096_9 _0.6088_9 0.6022_9 VOLUMES burette reading: FINAL 32.65_ m _33.49_ML_30.47ML burette reading: O INITIAL 3.09 mL 4.29 ML 1.19 mL Volume of NaOH used: minus 0 29.56 mL 29.20 ml 29.28 mL CALCULATIONS molar mass of KHP Show the calculation of the Molar Mass of KHP (KHCH.O4): Tips: - use the Periodic Table in your laboratory manual (inside front cover) to obtain relevant atomic masses. Nam risus an, ultrices ac magna. Your online site for school work help and homework help. At the end point the solution pH is 8.42. As you start adding the NaOH, and converting it eventually to K3PO4, any bits that were initially present as H2PO4(1-), or PO4(3-), or H3O(1+), or OH(1-), will all "come out in the wash". Your goal here is to standardize a solution of sodium hydroxide, #"NaOH"#, by using potassium hydrogen phthalate, #"KHP"#. In the first standardization the molarity of a sodium hydroxide solution (NaOH) will be determined by titrating a sample of potassium acid phthalate (KHP; HKC8H4O4) with the NaOH. It takes [c] NaOH = n/V = (0.00979/0.0950) = 0.103 mol dm -3 (cm 3 is converted into dm 3) Raw Data Lab 1: Preparation of KHP Acid Weight of weighing boat before adding KHP = 2.67 g Weight of weighing boat with KHP = 4.67 g not need to show your work for additional trials; just populate the table. Pellentesque dapibus efficitur laoreet. total volume of solution. Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. So, you know that at equivalence point, the reaction will consume #0.0024973# moles of #"KHP"# and #0.0024973# moles of #"NaOH"#, since that's what the #1:1# mole ratio tells you. 1.54g of KHP is equivalent to 0.00754 mol of KHP. figs.). We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Only one of the hydrogen atoms in KHP has acidic properties. Lorem ipsum dolor sit amet, consectetur adipiscing elit. If you're using phenolphthalein as your indicator, an excess of sodium hydroxide would cause the solution to be a brighter shade of pink than it should be at equivalence point. The number of moles of NaOH is found by multiplying the moles of KHP by the mole ratio of NaOH to KHP given by the above, balanced chemical reaction. Recall that the molarity \(\left( \text{M} \right)\) of a solution is defined as the moles of the solute divided by the liters of solution \(\left( \text{L} \right)\). Nam risus ante, dapibus a molestie consequat, ultr, ultrices ac magna. Fusce dui l, m ipsum dolor sit amet, consectetur adipiscing, sus ante, dapibus a molestie consequat, ultrices ac magna. used. Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. Where [c]KHP is the concentration of KHP Acid. How does neutralization reaction differ from using a buffer? Course Hero is not sponsored or endorsed by any college or university. Cross), Forecasting, Time Series, and Regression (Richard T. O'Connell; Anne B. Koehler), The Methodology of the Social Sciences (Max Weber), Educational Research: Competencies for Analysis and Applications (Gay L. R.; Mills Geoffrey E.; Airasian Peter W.), Introductory College Chemistry I Laboratory (CHEM 1411), Post Lab 4 1411 - Lab Report 4 for CHEM 1411 UVA, Introductory College Chemistry I Laboratory, Web Programming 1 (proctored course) (CS 2205), Art History I OR ART102 Art History II (ART101), Accounting Information Systems (ACCTG 333), Differential Diagnosis & Primary Care Practicum (NR-511), PHIL ethics and social responsibility (PHIL 1404), Managing Business Communications and Change (MGT-325), Fundamentals General, Organic, Biological Chemistry I (CHE 121), Professional Application in Service Learning I (LDR-461), Advanced Anatomy & Physiology for Health Professions (NUR 4904), Principles Of Environmental Science (ENV 100), Operating Systems 2 (proctored course) (CS 3307), Comparative Programming Languages (CS 4402), Business Core Capstone: An Integrated Application (D083), Student-HTN-Atherosclerosis Unfolding Reasoning, Summary Media Now: Understanding Media, Culture, and Technology - chapters 1-12. a) Calculate the concentration of the NaOH solution One necessary piece of information is the saponification number. Donec aliquet. You know how many moles of sodium hydroxide were needed to reach the equivalence point, and the volume of sodium hydroxide solution that delivered that many moles to the reaction. _W}P?l?QhE$Bk!=9KgieR}EKJ#Vb$av3(>?"z%dH~HJ}Zjo]T5m$jEVRlcp,. The expected % uncertainty that was expected was 0.500%, and the uncertainty I obtained was 0.503%. <>>> 10 grams KHP to mol = 0.14069 mol 20 grams KHP to mol = 0.28137 mol 30 grams KHP to mol = 0.42206 mol 40 grams KHP to mol = 0.56275 mol 50 grams KHP to mol = 0.70343 mol 100 grams KHP to mol = 1.40687 mol 200 grams KHP to mol = 2.81373 mol Want other units? Lorem ipsum dolor sit amet, consectetur adipiscing elit. 3 0 obj How do you find the concentration of NaOH? your work. It is acidic and gives a clear, sharp end- point when titrated with sodium hydroxide and using phenolphthalein as the indicator. <> Nam lacinia pulvinar tortor, inia pulvinar tortor nec facilisis. Lorem ipsum dolor sit, ac, dictum vitae odio. Moles NaOH used. Mole ratio = 1 KHP:1NaOH From the mole ratio, the number of moles of NaOH = 0.00979 mol. endobj Nam risus ante, dapibus a molestie consequat, ultr, at, ultrices ac magna. The moles of KHP was found by dividing the mass of the sample of pure KHP by the molar mass for KHP. endobj So the moles of solute are therefore equal to the molarity of a solution multiplied by the volume in liters. The molarity of the NaOH solution is So what is being weighed isnt totally NaOH, but also the moisture that it has absorbed. {}Oqq=vq.L, v1? =_Q1{Ox#1#cdw~-g"qy]F$bM@(JzEAtDC:H.,B?k=hV'K"g~F`ZYZ?fq2Vh5?N4pddL{4yQKsf)3^9"N\X$b:4Kna|:4~Ys-ISE CALCULATIONS molarity of NaOH For each trial calculate the precise molarity of the NaOH solution using the data for the listed trial. At the endpoint the moles of HCl = the moles of NaOH so all that is present is H2O, Cl, and Na+. <>>> Empty Beaker= 23. Therefore, the moles of KHP is equal to the moles of NaOH. of an unknown monoprotic acid dissolved in water to a final volume of 50.00 mL. Conc. endobj 0. A mole is equal to 6.022 x 1023 molecules.) By doing the titration and making a plot of the volume of NaOH added versus the resulting pH of the solution, we find that the equivalence point occurs at 0.04398 L of NaOH. You start with 0.5100 g of KHP . It is acidic and gives a clear, sharp end- point when titrated with sodium hydroxide and using phenolphthalein as the indicator. % Uncertainty of (aq) KHP in Volumetric Flask = (0.1/100) x 100. CALCULATIONS molarity of NaOH For each trial calculate the precise molarity of the NaOH solution using the data for the listed trial. Most questions answered within 4 hours. So, assuming KHP is potassium hydrogen phthalate, we have the following reaction: NaOH + C 8 H 5 KO 4 ==> H 2 O + C 8 H 4 NaKO 4 molar mass KHP = 204 g/mole Science Teacher and Lover of Essays. At the equivalence point in a neutralization, the moles of acid are equal to the moles of base. The balanced equation is: NaOH (aq) + HCl (aq) NaCl (aq) + H 2O (l) So the mole ratio NaOH:HCl is 1:1. Number of moles of KHP in 2.00 grams = (m/M) = (2/204.22) mol = 0.00979 mol [c] KHP = n/V = (0.00979/0.1) mol dm -3 Number of moles of KHP in 0.01 dm 3 of solution in conical flask = [c] x V = 0.0979 x 0.01 = 9.79 x 10 -4 mol. pdf, Gizmos Student Exploration: Effect of Environment on New Life Form, Ejemplo de Dictamen Limpio o Sin Salvedades, Leadership class , week 3 executive summary, I am doing my essay on the Ted Talk titaled How One Photo Captured a Humanitie Crisis https, School-Plan - School Plan of San Juan Integrated School, SEC-502-RS-Dispositions Self-Assessment Survey T3 (1), Techniques DE Separation ET Analyse EN Biochimi 1, Reproduce your KHP standard data. answer questions 6-11. Because the ratio between C8H5KO4 and NaOH is one to one you will need the same number of moles of NaOH as KHP to reach the equivalence point. Finally, divide the moles of \(\ce{H_2SO_4}\) by its volume to get the molarity. M(NaOH)= 0,0688 (mol)/L V(NaOH) = 0,0469 L For a titration is necessary that the moles of NaOH are equivalent to the mole of KHP (that have a MM of 204,22g/mol). We can convert that to grams using its molar mass (180.157 grams per mole) and we get the final grams of 0.305 grams (305mg) of Aspirin present in the solution of 1 dissolved tablet. Why do neutralization reactions produce heat? Legal. The resulting percentage error out of this deviation is: Potassium Hydrogen Phthalate ( referred to in the experiment as KHP) was a brittle, white, crystalline substance. KHP 1. The distance "around the block" (amount of titrant required) doesn't change, regardless of the house (equilibrium-driven side conditions) position selected initially. So the steps are grams KHP to moles KHP to mmol KHP to mmol NaOH to ml NaOH as your final answer: Lorem ipsum dolor sit amet, consectetur adipiscing es a molestie consequat, ultrices ac magna. As you know, molarity is defined as moles of solute per liters of solution. Nam lacinia pulvin, Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec aliquet. Suppose that a titration is performed and \(20.70 \: \text{mL}\) of \(0.500 \: \text{M} \: \ce{NaOH}\) is required to reach the end point when titrated against \(15.00 \: \text{mL}\) of \(\ce{HCl}\) of unknown concentration. the KHP respectively in the balanced chemical equation. Lorem ipsum dolor sit amet, consectetur adi, trices ac magna. From the mole ratio, calculate the moles of \(\ce{H_2SO_4}\) that reacted. In a titration where neutralization occurs, it is 1 H+ to 1 OH- molar ratio. You can calculate the percent error by using the formula, #color(blue)("% error" = (|"approximate value" - "exact value"|)/"exact value" xx 100)#, #"% error" = (|0.07878 - 0.100|)/0.100 xx 100 = 21.22%#. For Free. Initial burette reading. A student weighs out 0.568 g of KHP (molar mass = 204 g/mol) and titrates to the equivalence point with 36.78 mL of a stock NaOH solution. First determine the moles of \(\ce{NaOH}\) in the reaction. Report this using the correct number of significant figures. Then convert this to the number of moles of NaOH that were neutralized in the bitration (refer to balanced Eqn 1 shown in the lab manual). To begin, we need to determine how many moles of KHP there are: KHP has a molecular weight of 204.22 g/mol, and one mole of KHP is equal to 354.5 mg divided by 204.22 g/mol, which equals 0.001736 mol. 4 0 obj Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. 2.752 x 10-1 mol 2.693 x 10-2 mol 2.693 x 10-3 mol 3.712 x 102 mol. Lorem ipsum dolor sit amet, consectetur adipiscing elit. 0 / 5 = 0. Therefore, due to flaws in raw data values taken from systematic errors, there has been a deviation in uncertainty too, indicating the impact of methodical flaws. When the solution starts becoming dark pink abruptly, immediately reduce the rate of flow of NaOH from the burette, and after the pink can no longer be eliminated, shut off the supply. Fusce dui lectus, congue vel laoreet ac, consectetur adipiscing elit. 35,000 worksheets, games, and lesson plans, Marketplace for millions of educator-created resources, Spanish-English dictionary, translator, and learning, Diccionario ingls-espaol, traductor y sitio de aprendizaje, a Question The end-point colour in Experiment 5 is the palest-possible light-pink that won't fade within 30 seconds: Experts are tested by Chegg as specialists in their subject area. He found out that it required 18.5 mL of NaOH to reach the endpoint of the titration. Article last reviewed: 2020 | St. Rosemary Institution 2010-2022 | Creative Commons 4.0. This means that you can calculate its actual molarity by dividing the two - do not forget to convert the volume from milliliters to liters by using the conversion factor, #["NaOH"] = "0.0024973 moles"/(31.70 * 10^(-3)"L") = color(green)(|bar(ul(color(white)(a/a)"0.07878 M"color(white)(a/a)|)))#. Therefore, due to flaws in raw data values taken from systematic errors, there has been a deviation in uncertainty too, indicating the impact of methodical flaws. However, there has been a deviation of 0.9 cm 3, which is significant, but not high. Nam risus ante, dapibus a molestie consequat, ultrices ac mm risus ante, dapibus a molestie consequat, ultrices ac magna. : an American History (Eric Foner), Chemistry: The Central Science (Theodore E. Brown; H. Eugene H LeMay; Bruce E. Bursten; Catherine Murphy; Patrick Woodward), Campbell Biology (Jane B. Reece; Lisa A. Urry; Michael L. Cain; Steven A. Wasserman; Peter V. Minorsky), Principles of Environmental Science (William P. Cunningham; Mary Ann Cunningham), Civilization and its Discontents (Sigmund Freud), Psychology (David G. Myers; C. Nathan DeWall), Business Law: Text and Cases (Kenneth W. Clarkson; Roger LeRoy Miller; Frank B. Nam risus ante, dapibus a molestie consequat, ultrices ac magna. 0. Fxp yNptvy}Fwz(.m2ALXJBzcw:=mP-:|jXV>eEB/5 \3/vG~E,L.2iw$UT5? The volume of \(\ce{H_2SO_4}\) required is smaller than the volume of \(\ce{NaOH}\) because of the two hydrogen ions contributed by each molecule. moles = mass/MM . In a titration where neutralization occurs, it is 1 H + to 1 OH-molar ratio.If we can figure out how many moles of KHP there is, we would find how many moles of H + there is (KHP to H + is a 1 to 1 molar ratio-monoprotic acid thing again).This can be found by dividing the molar mass of KHP into the mass of KHP (.568/204-the mass,gram units, cancel and moles remain . [c]NaOH = n/V = (0.00979/0.0950) = 0.103 mol dm-3 (cm3 is converted into dm3), Weight of weighing boat before adding KHP = 2.67 g, Weight of weighing boat with KHP = 4.67 g, Weight of weighing boat after transfer = 2.68 g, Mass of KHP Transfer = Weight of weighing boat with KHP Weight of weighing boat after transfer, *Initial volume is the initial reading of the burette and final volume is the reading after adding NaOH solution, From mole ratio, number of moles of NaOH = 0.00974 mol. Procedure The experiment consisted of three separate parts: the standardization of NaOH using the acid KHP, the determination of an acetic acid solution's molarity using the standardized NaOH, and using the same NaOH to find a sulfuric acid solution's molarity. The above equation works only for neutralizations in which there is a 1:1 ratio between the acid and the base. The crystals required intense stirring before they could be dissolved in water. Do round off the final result in each trial to the proper number of significant digits. (NaOH) = ( g KHP)( 1 mol KHP / 204.23 g) ( 1 mol NaOH / 1 mol KHP) / (V L of NaOH) (0.905 g KHP) ( 1mol KHP ) ( 1mol __ ) = 0.00443 . The titration of NaOH with KHP involves adding NaOH from the burette to a known volume of KHP. Make sure the conical flask is directly under the pipette, with no contact with the inner walls, so as to get a more accurate measure of the volume. %PDF-1.5 c) Calculate the Ka of the unknown monoprotic acid, Explore over 16 million step-by-step answers from our library, ar tortor nec facilisis. 7.50 X 10 -2 moles X 204.22 g KHP/ 1 mole = 15.3 g KHP 3 0 obj Donec aliquet, View answer & additonal benefits from the subscription, Explore recently answered questions from the same subject, Test your understanding with interactive textbook solutions, Fundamentals of General, Organic, and Biological Chemistry, Chemistry: An Introduction to General, Organic, and Biological Chemistry, Organic Chemistry with Biological Applications, Introduction to General, Organic and Biochemistry, Macroscale and Microscale Organic Experiments, Explore documents and answered questions from similar courses. 0.02/0= 0 M, Copyright 2023 StudeerSnel B.V., Keizersgracht 424, 1016 GC Amsterdam, KVK: 56829787, BTW: NL852321363B01, Brunner and Suddarth's Textbook of Medical-Surgical Nursing (Janice L. Hinkle; Kerry H. Cheever), Biological Science (Freeman Scott; Quillin Kim; Allison Lizabeth), Give Me Liberty! Type of Acid/Base Indicator used Phenolphthalein. That's one problem with abbreviations. M= moles/liter, so we have 25 mL of a 0.10 mole/liter solution. A Chem 1515 student dissolved 0.33 grams of KHP in 25.0 mL of water. The important thing to notice here is that you have a #1:1# mole ratio between the two reactants. Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. When the endpoint is reached the addition of titrant should be stopped. Get a free answer to a quick problem.