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. How do you find the concentration of NaOH? First you need to write out the balanced equation to determine the mole ratio between C8H5KO4. Potassium hydrogen phthalate, KHC8H4O4 (abbreviated KHP), is a non-hygroscopic, crystalline, solid that behaves as a monoprotic acid. In this case, 2 moles of NaOH are required to titrate 1 mole of H 2 SO 4. Oliver Twist: Characters, Setting, Style, Audience and Diction, On the Sidewalk, Bleeding: Analysis & Theme, Carolyn Meyers White Lilacs: Summary, Conflict, Analysis, President Ronald Reagans John F. Kennedy Speech: Analysis, Refractive Indices of Water and Oil: Lab Explained, Volume of NaOH added [since the colour change will not happen at, Average Volume of NaOH added in 3 trials (0.1 cm. 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 if you use the dimensional analysis method). 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. How do you find the concentration of NaOH? - Wise-Answer KHP 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. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
So the moles of solute are therefore equal to the molarity of a solution multiplied by the volume in liters. mol KHP= (0,436g)/(204,22 (g/(mol))) = 0,00213 mol . ATTENTION: Help us feed and clothe children with your old homework! 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. (Or, which house did you just return that dog to?). Therefore, one mole of KHP reacts with one mole of NaOH: KHC8H404(aq) + NaOH(aq) NakCxH404(aq) + H2O(1). %
The half equivalence point corresponds to a volume of 13 mL and a pH of 4.6. Next, we are able to determine the concentration of the NaOH solution by doing the following: Full Beaker= 25. So what is being weighed isnt totally NaOH, but also the moisture that it has absorbed. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam risus ante, dapibus a molestie consequat, ultrices ac magna. answered 07/11/19, Ph.D. University Professor with 10+ years Tutoring Experience. Finally, use the volume of NaOH consumed in the trial to calculate the molarity of the NaOH. This tells you that at you can reach the equivalence point by reacting equal number of moles of #"KHP"# and of #"NaOH"#. x\[s~L& Ng's:;-HT_v@II{^|.dR~|Ud>?.w_W1"^%7Wg1ec? The formula and structure for the carboxylic acid KHP is shown in Figure 5.1. No packages or subscriptions, pay only for the time you need. %PDF-1.5
Based on this equation, we need one mole of KPH to react with each mole of NaOH. Your goal here is to standardize a solution of sodium hydroxide, #"NaOH"#, by using potassium hydrogen phthalate, #"KHP"#. Nam lacinia pulvin, Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. tech2 - Vanderbilt University As you know, molarity is defined as moles of solute per liters of solution. This flaw was due to allowing excess sodium hydroxide to flow, causing the KHP solution to become pinker than it should have. As you can see, the actual molarity of the solution you prepared is relatively small compared with your target of #"0.100 M"#. PDF Chem 141 Titration Lab Lecture Notes - University of Richmond 2 0 obj
This might have caused some deviations because the volume of sodium hydroxide added was excess. moles NaOH = moles KHP x 1 mole NaOH 1 mole KHP 3. <>
Convert between KHC8H4O4 weight and moles Elemental composition of KHC8H4O4 Sample reactions for KHC8H4O4 Formula in Hill system is C8H5KO4 This is characteristic of a major error in your experiment. strong bases. 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-. Lorem ipsum doec aliquet. Lorem ipsum dolor sit, ac, dictum vitae odio. Introduction Sodium hydroxide is hygroscopic and absorbs water from the air when you place it on the balance for massing. NaOH + C8H5KO4-->NaC8H4KO4 + H2O. The expected % uncertainty that was expected was 0.500%, and the uncertainty I obtained was 0.503%. To get the molar amount of acid used for the experiment, use its molar mass 0.5100 g molar mass of KHP 1 mole KHP 204.22 g = 0.0024973 moles KHP Pellentesque dapibus efficitur laoreet. Get a free answer to a quick problem. and KHP are equal and we used an indicator to find this point. Our answer is 0.01692 moles of NaOH added and the same number of moles of Aspirin neutralized. Learn how to calculate the mass of KHP (potassium hydrogen phthalate) to standardize a NaOH (sodium hydroxide) solution. Because the ratio betweenC8H5KO4 and NaOH is one to one you will need the same number of moles of NaOH as KHP to reach the equivalence point. answered 11/20/13, Friendly tutor for ALL math and physics courses. 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. Pellentesque dapibus efficitur laoreet. Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. Why do neutralization reactions produce heat? a. Nam risus ante, dapibus a molestie consequat, ultrices ac mm risus ante, dapibus a molestie consequat, ultrices ac magna. For Mastery on this assignment, you must Master 10 or more of these questions. From mole ratio, number of moles of NaOH = 0.00979 mol. Also, the % uncertainty of the volume of NaOH was 1.05%, taking the value of 9.50 cm 3. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Lorem ipsum dolor sit amet, coce dui lectus, congue vel laoreet ac, dictum vitae odio. 1 0 obj
How can I find volume of NaOH used up on test data? And how to find [NaOH]? Donec aliquet. You do The concentration in units of molarity (moles/liter of solution) is just given by the number of moles of NaOH divided by the volume of liquid it was contained in: > ()@ NaOH KHP NaOH NaOH n n NaOH M VV 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? Nam lacinia, iscing elit. The percentage uncertainty calculated of the concentration of NaOH was 2.57%, which indicates that the level of precision, although not low, could have been better. [NaOH) - mol/L Calculation for Trial 2. The NaOH may not have reacted with the exact amount of KHP expected. I started to make the same mistake as you. Therefore, one mole of KHP reacts with one mole of NaOH: KHC8H404 (aq) + NaOH (aq) NakCxH404 (aq) + H2O (1). 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%#. PDF Titration of a Weak Acid General Chemistry - Colby College I assumed KHP was a potassium phosphate, but was troubled by a completely incorrect formula. Show your work. Lorem ipsum dolor sit amet, consecec facilisis. Solved 2. In a second titration with the same solution of - Chegg Number of moles of KHP in 2.00 grams = (m/M) = (2/204.22) mol = 0.00979 mol, Number of moles of KHP in 0.01 dm3 of solution in conical flask = [c] x V. From the mole ratio, the number of moles of NaOH = 0.00979 mol. Nam risus ante, dapibus a molestie conse, onec aliquet. <>
Nam risus an, ultrices ac magna. The molar mass of KHP is approximately 204.22 g/mol. 1. However, there has been a deviation of 0.9 cm3, which is significant, but not high. Report this using the correct number of significant figures. The moles of KHP used in the titration can be calculated from the mass of the KHP sample. Convert grams NaOH to moles - Conversion of Measurement Units Acid - Base Titrations - Chemistry Land \[\text{moles acid} = \text{moles base}\nonumber \] . KHP is slightly acidic, and it is often used as a primary standard for acidbase titrations because it is solid and air-stable, making it easy to weigh accurately. One experimental flaw which resulted in readings inconsistent with the literature value was due to human error. The distance "around the block" (amount of titrant required) doesn't change, regardless of the house (equilibrium-driven side conditions) position selected initially. Fusce dui lectus, congue vel laoreet ac, dictum vitae odio. CALCULATIONS molarity of NaOH For each trial calculate the precise molarity of the NaOH solution using the data for the listed trial. Nam lacinia pulvinar tortor nec facilisis, cing elit. These two atoms combine with the oxygen from the NaOH to form H2O, which is the chemical formula for water. 1 Digital Balance (up to 2 decimal places accuracy), % Uncertainty of (aq) KHP in Volumetric Flask = (0.1/100) x 100, % Uncertainty of (aq) KHP in Pipette = (0.1/10) x 100. a) Calculate the concentration of the NaOH solution Unknown Acid Postlab 1 - Chem Lab - Unknown Acid Postlab 1 - Studocu Type of Acid/Base Indicator used Phenolphthalein. However, as NaOH was added further, there came a point when no amount of stirring changed the pink colour. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. The deviation in the volume, however, is not the only indicator of noticeable systematic errors. Conversely, for the titration of a weak base with strong acid, the pH at the equivalence point is less than 7 because only the conjugate acid is present. The uncertainty of 2.57% indicates that my values were accurate up to within 2.57%. molecular equation: KHC8H4O4(aq) + NaOH (aq) KNaC8H4O4(aq) + H2O(l) 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. { "21.01:_Properties_of_Acids" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.
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