You cannot then use this concentration of NaOH to estimate the percentage composition of the same KHP. The expected % uncertainty that was expected was 0.500%, and the uncertainty I obtained was 0.503%. To also determine the concentration of NaOH in the KHP solution. taken from the buret containing the NaOH was 0.52 mL … The titration of NaOH with KHP involves adding NaOH from the burette to a known volume of KHP. Hypothesis: When KHP is added to the solution of NaOH and the indicator, the solution will turn clear and neutralize. Part I: Preparing KHP sample To standardize your NaOH solution, measure out approximately 0.5g of the KHC 8 H 4 O 4 (potassium hydrogen phthalate, KHC 8 H 4 O 4, MW = 204.2 g/mol) into an Erlenmeyer flask.Add 30.0 mL of water to the flask and dissolve the KHC 8 H 4 O 4.. Ans. D. Molarity of NaOH from Sample 1 Sample 1 contained 0.002509 mole of KHP, and required 0.02275 L of NaOH to reach the endpoint (indicator color change). Use your average value of NaOH volume to calculate its molarity. Moles (nvf) of KHP in volumetric flask = mKHP/MKHP where MKHP is the Molar Mass of KHP (204.22 g), Moles of KHP in 10 cm3 of solution in where V is a given volume of water, Volume of NaOH added = Final Volume – Initial Volume, [c]KHP = (n/V) mol dm-3 = (0.00974/0.1) mol dm-3 = 0.0974 mol dm-3. of NaOH that reacted with the KHP. Allowing the KHP to flow along the inner walls of the conical flask. I just what to know how to solve these … However, this, being only 0.01 grams of the expected value, could have only constituted a very small portion of the error. Taking the value of 9.50 cm3 and mass of 2 grams, the concentration of NaOH should have been 0.103 mol, but the value I obtained due to the excessive deviation gave me 0.0937 mol. Article last reviewed: 2019 | St. Rosemary Institution © 2010-2020 | Creative Commons 4.0. Question: in a neutralization reaction 45.7 mL of 0.500 M sulfuric acid is required to completely react with 20.0 mL of sodium hydroxide. NaOH solution of known molarity cannot be directly prepared without resorting to an air-and-water-free environment. 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 mole ratio, number of moles of NaOH = 0.00979 mol. V of NaOH used =(31,26-0,23) = 31,03 mL = 0,03103 L mol NaOH = M V =M 0,03103 L but the mol of the two substance are the same therefore Molarity of NaOH = (mol KHP)/ (V NaOH … © 2021 Yeah Chemistry, All rights reserved. Also, the % uncertainty of the volume of NaOH was ±1.05%, taking the value of 9.50 cm3. 2. KHP solution (L) 0.0125 0.0120 0.0120 Molarity of NaOH to neutralize KHP solution (mol/L) 0.5882 0.6140 0.6133 Molarity of NaOH to neutralize KHP solution (M) 0.5882 0.6140 0.6133 Sample Calculation For The Average Science Teacher and Lover of Essays. To determine the molarity of NaOH solution, student took 3.5 g of KHP (KHP – Potassium hydrogen phthalate; Molar mass = 204.22 g/mol) and dissolved in 50 mL of water and titrated with the given unknown molarity NaOH solution loaded in burette. The average molarity of the sodium hydroxide solution was found to be 0.155 M after standardization. Calculate the molarity of the solution to 4 significant figures. Free proofreading and copy-editing included. Calculate the moles of KHP, NaOH, and the molarity of the NaOH. Hypothesis: When KHP is added to the solution of NaOH and the indicator, the solution will turn clear and neutralize. Therefore, NaOH solution is standardized by titrating weighed samples of a primary standard acidic substance, potassium hydrogen phthalate (KHC 8 H 4 O 4 , "KHP", molar mass 204.2 g). Allowing the KHP solution to become too pink. NaOH + HOOC-C6H4-COOK Æ NaOOC-C6H4-COOK + H2O By measuring the volume of the ~0.2M NaOH solution dispensed from the buret that is necessary to react completely with a weighed sample of KHP, the exact concentration of NaOH solution is 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. thank you so much!! It is important to note that the pink color in three titrations were all slightly different, some being darker than others. PROCEDURE PREPARATION OF THE NaOH SOLUTION The NaOH solution is a 50% by mass NaOH (.15mole), density of 1.525g/ml The average molarity of the NaOH from the KHP trials i got was 0.1405m Trials (volume) #1: 47.50ml acetic acid 47.50ml NaOH #2: 33.50ml acetic acid The standardized NaOH solution will then be used to determine the molarity of acetic acid in an unknown acetic acid sample. These errors were avoidable. #Trial 1: # Molar mass of KHP = 204.22 g mol-1 # Mass of KHP = 0.846 g # Moles of KHP = Mass / Molar mass = 0.846 g / (204.22 g/mol) = 0.004143 mol # Volume of NaOH = … Titration data for four trials for approximately 0.50 g of KHP titrated with NaOH of unknow concentration. As the transparent NaOH solution came into contact with transparent phenolphthalein in the KHP solution, it turned pink which on shaking became transparent. A 25.00-mL aliquot of an unstandardized HCl solution is titrated with the The volume of the volumetric flask is 250.0 mL. 2.00 grams was the amount expected to be taken, but the experimental amount was 1.99 grams. What is the molarity of the base? A 0.8234-g sample of "KHP" required 38.76 mL of NaOH for titration to the phenolphthalein endpoint. NaOH has 1 equivalent per mole so Normality = Molarity. yeah it would be KHP+NaOH --> H20+Na+KP This outlines a straightforward method to calculate the molarity of a The theoretical value of NaOH to be poured was 9.50 cm3, and more or less than 0.1 cm3 of that value. Sufuric acid has 2 equivalents of acid per mole so N = 2eqM = 2eq mol.