Acid Base Titration FINDING THE CONCENTRATION OF A BASIC SOLUTION USING THE acid base NEUTRALIZATION REACTION AND ESTIMATING THE AMOUNT OF THE BASIC COMPOUND DISSOLVED IN THE GIVEN SOLUTION THIS EXPERIMENT HAS THREE STEPS 1 Preparing a STANDARD SOLUTION 2 STANDARDIZING AN ACID SOLUTION 3 ESTIMATING THE AMOUNT OF THE BASIC COMPOUND DISSOLVED IN THE GIVEN SOLUTION 1 Standard solution Preparation of a standard solution of sodium carbonate Theory A standard solution is one whose concentration is accurately known A primary standard is a substance that can be used to make a standard solution directly A primary standard such as anhydrous sodium carbonate is available in a pure state is stable and is water soluble Anhydrous sodium carbonate Na2CO3 has a molar mass of 106 g mole For example 0 1 M solution is made up using a 250 cc volumetric flask From the definition and principles of expressing the concentration of solutions for 250 cc of 0 1 M sodium carbonate solution the mass of sodium carbonate required is 106 x 0 1 x 250 1000 2 65 g Procedure Using a balance measure accurately x g close to the desired amount of sodium carbonate for the molarity of your choice of pure anhydrous sodium carbonate on a watch glass Slowly transfer the sodium carbonate with stirring to about 50 cc of deionized water in a clean 250 cc beaker Leave any particles of sodium carbonate stuck to the watch glass as they are Continue stirring the mixture with a stirring rod until the sodium carbonate has fully dissolved Using a wash bottle wash off the solution on the stirring rod with de ionized water into the beaker Pour the solution through a clean funnel into the 250 cc volumetric flask Using a wash bottle rinse out the beaker several times with de ionized water and add the rinsings to the solution in the flask Rinse the funnel with de ionized water allowing the water to run into the flask Fill the flask to within about 1 cm of the calibration mark and then add the water dropwise using a dropping pipette until the bottom of the meniscus just rests on the calibration mark Stopper the flask and invert it several times to ensure a homogeneous evenly mixed solution Label the flask Using the amount of sodium carbonate transfered calculate the exact molarity of the solution you have prepared Data and calculations Intended molarity Amount required to prepare the standard solution of the above molarity of M in cc weight of the empty weigh boat weight of the weigh boat sodium carbonate weight of the weigh boat remnants of sodium carbonate amount of sodium carbonate transferred MOLARITY of the prepared sodium carbonate solution REPORT Questions 1 What is a standard solution 2 Why is it possible to make up a standard solution of sodium carbonate directly 3 Why is it necessary to wash the solution off the stirring rod into the beaker 4 Why are the rinsings from the beaker added to the volumetric flask 5 When the solution has been made up why is it necessary to mix the contents of the flask thoroughly What feature of the volumetric flask makes this particularly necessary 6 Why is a funnel used in transferring the solution from the beaker into the volumetric flask 7 How many grams of sodium carbonate are required to prepare a solution of 2 M in a 2L volumetric flask 8 What is the molarity of the solution obtained by dissolving 2 685 g of sodium hydrogen carbonate in 500 00 mL of de ionized water in a volumetric flask labeled as 500 00 mL 2 Standardization of an acid solution The reaction between an acid and a base is called a Neutralization reaction The net ionic equation is shown below H aq OH aq H2O In this titration a base of known concentration is given to you or you have prepared and you are required to use this solution to find the concentration of an acid The Base given to you prepared by you is a solution of sodium carbonate and the acid is Hydrochloric acid The acid is taken in a clean rinsed burette and titrated against the solution of sodium carbonate taken in an erlenmeyer flask At the end point equivalence point the number of moles of the base are equal to the number of moles of the acid The end point is detected with the help of an acid base indicator In layman s terms equivalence point is the point in a titration where just enough titrant has been added to react with all the analyte present The indicator is a chemical compound which changes colour at the equivalence point and is the visual indication that the equivalence point has been reached Na2CO3 aq 2 HCl aq 2 NaCl aq H2O CO2 Procedure 1 Clean a burette pipette and a 250 mL erlenmeyer flask with distilled water 2 Rinse the burette with the given solution of Hydrochloric acid and fill it up to the mark with the acid solution Make sure that there are no air bubbles in the nozzle Clamp the burette to the burette stand 3 Rinse the pipette with the given sodium carbonate solution Pipette out 20 mL of this base solution into the Erlenmeyer flask using the rinsed pipette Add a drop or two of the acid base indicator and swirl the contents of the flask observe the colour 4 Titrate the solution with the acid in the burette drop wise with constant swirling until a sharp colour change is observed with the addition of one drop of the solution Note the volume on the burette taking all the necessary precautions 5 Repeat the experiment at least 4 times or until concurrent titer values are obtained Tabular form S No Volume of sodium carbonate solution Initial Burette Reading Final Volume of HCl Calculations INDICATOR used Colour change V1 Volume of Sodium carbonate M1 Molarity of sodium carbonate n1 Number of moles of sodium carbonate V2 Volume of HCl M2 Molarity of HCl n2 Number of moles of HCl At equivalence point as the number of moles of sodium carbonate are equal to the number of moles of Hydrochloric acid Molarity of HCl solution M Amount of HCl in the given solution g L QUESTIONS 1 What volume of 0 0080 M sulphuric acid is needed to neutralize 20 00 mL of 0 0020 M barium hydroxide solution 2 How would the following errors effect your experiment a The solution was splashed from the erlenmeyer flask during titration b An air bubble in the nozzle of your burette came out during titration c Too much indicator was added d The solution in the burette was run past the indicator colour change 3 ESTIMATING THE AMOUNT OF THE BASIC COMPOUND DISSOLVED IN THE GIVEN SOLUTION Problem solution Execute the titration in the same manner as above using the given problem solution PAY