2011 - 2012
Table of Contents
|Page |Title |Module |Skills tested | |# | | | | |3 |Standardisation of hydrochloric acid |2 | | |5 |Calibration of a pipette |2 |ORR, A&I | |6 |Redox Titration / H2O2 vs KMnO4 |2 |M&M, A&I | |8 |Back Titration |2 | | |10 |Gravimetric analysis of hydrated salt |2 | | |11 |Flame tests |2 | | |12 |Reactions of cyclohexane and cyclohexene |1 |ORR,A&I | |14 |Paper Chromatography |2 | | |15 |Water polluting inorganic ions |3 | | |16 |Distillation of a sample of rum |3 | | |17 |Salted peanuts “Fuller” |2 |P&D | |17 |Antique or Fake |2 |P&D | |17 |Margarine vs Butter |1 |P&D | |18 |Identity of sample X |3 |M&M, ORR, A&I |
STANDARDISATION OF HYDROCHLORIC ACID
SKILLS TESTED: None
AIM: The purpose of this experiment is to determine the concentration of a solution of hydrochloric acid using a standard solution of sodium carbonate.
Introduction: The salt reacts with hydrochloric acid in a 1: 2 molar ratio (1 mole sodium carbonate : 2 moles acid). In this experiment you will prepare a standard solution of sodium carbonate and titrate this solution against a solution of hydrochloric acid of unknown concentration using methyl orange as indicator.
Preparation of the standard solution.
1. Weigh 2.0 g of sodium carbonate to the nearest 0.01g. Dissolve the solid in the minimum amount of water. 2. Record your readings in the table below.
3. Transfer the solid and washings to a volumetric flask. Your teacher will guide you. 4. Add distilled water, swirling at intervals to mix the contents, until the level is within 1 cm of the calibration mark on the neck of the flask. 5. Using a wash bottle, carefully add distilled water to bring the bottom of the meniscus to the mark. 6. Insert the stopper and shake thoroughly (by inversion) to ensure complete mixing.
1. Rinse and fill the burette with hydrochloric acid solution. Record the initial burette reading. 2. Using a pipette filler, rinse the pipette with some of the sodium carbonate solution and carefully transfer 25cm3 of the solution to a clean conical flask. 3. Add 2 drops of the methyl orange indicator and swirl the flask. 4. Run hydrochloric acid from the burette into the flask, with swirling until an orange colour (with a hint of pink) permanent colouration is seen. Record the burette reading. 5. Repeat the titrations as many times as is necessary to obtain consistent results. 6. Do...
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