Results analysis to obtain the amounts of all the components Approach to the

Results analysis to obtain the amounts of all the

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Results analysis to obtain the amounts of all the components Approach to the problem For standardisation of HCl, conduct pre-calculations for the volume of aq NaOH to determine the concentration of hydrochloric acid. Draw a ICE (Inititial, Change and Eqm) table to determine the change in amount of acid and alcohol For two different initial mixtures, the volume of HCl used is constant and the total mass of CH 3 CH 2 COOH and CH 3 OH used for both mixtures has to be less than or equal to 10g (as these values are given in the qn) Suitable choice of apparatus for titration of aq NaOH with HCl/ CH 3 CH 2 COOH such as pipette, burette and acid-base indicator used and measurement of HCl using a pipette/ burette and measurement of CH 3 CH 2 COOH and CH 3 OH using a mass balance Process to reaction mixture to reach equilibrium such as placing the reaction mixture in a sealed container and left for one week Titration of HCl/ CH 3 CH 2 COOH against aq NaOH
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H2 Chemistry 9647 2015 Experimental pre-calculations Assuming that the concentration of HCl is 3.00 mol dm 3 , A 10cm 3 pipette is used to measure the volume of HCl. Vol of NaOH required = భబ భబబబ × . బబ . ଴଴ = 0.0300dm 3 = 30.0 cm 3 (less than max capacity of burette, 50 cm 3 ) Determination of accurate concentration of HC l (Standardisation of HC l ) 1. Fill up the burette with NaOH, noting the initial volume reading. 2. Pipette 10.0 cm 3 of HCl and transfer it to a 100 cm 3 conical flask. 3. Add two drops of bromothymol blue indicator to the HCl in the conical flask. 4. Carry the titration against NaOH until permanent green colour is obtained from the initial yellow solution. OR other suitable indicator with correct colour change 5. Repeat titration until at least 2 consistent titre readings are obtained (titre volume differ not more than 0.10 cm 3 ). Use the average of these 2 consistent titres for subsequent calculations. Pre-calculation and results analysis for determining amt of reagents to be used for the esterification reaction - Recognise that the volume of water is equal to the volume of hydrochloric acid and to link the mass of water to the volume of hydrochloric acid given the density of water. Using the M r values of propanoic acid, methanol and water, volume of HCl = volume of water and mass of HCl = mass of water = volume of HCl and density of water = 1 g cm -3 CH 3 CH 2 COOH + CH 3 OH CH 3 CH 2 COOCH 3 + H 2 O Initial amt/mol mass/ 74 =x Mass/32 = y 0 Vol of HCl/ 18 = z Change in amt/mol -(x-w) -(x-w) mass/74 – w = + x –w + x –w Eqm amt/mol w Mass/32 - (x –w) = y – (x –w) x – w z + (x - w) Experiment to carry out the esterification reaction 1. Using a mass balance, weigh out 4 g of CH 3 CH 2 COOH and 2 g of CH 3 OH into a clean and dry 250 cm 3 conical flask. 2. Pipette 10 cm 3 of HC l and transfer it to the reaction mixture in the conical flask slowly with swirling to ensure that the solid reagents are dissolved. Seal the conical flask.
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