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Determine the relative formula mass and the molecular formula of succinic acid
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Introduction
Experiment: To determine the relative formula mass and the molecular formula of succinic acid Aim: Using volumetric analysis, with a known standard solution of NaOH, to titrate a solution of succinic acid to determine its molar concentration and hence it's molecular mass. Principle: Given that succinic acid is a dibasic acid with the molecular formula HOOC - (CH2) n - COOH where n is a number between 1 and 4 (both inclusive). H2 A + 2NaOH Na2A + 2H2O 1 Mole 2 moles In the experiment a standard solution of succinic acid with a known gram - concentration is allowed to titrate to equilibrium with a convenient quantity of 25 cm3 of the standard solution of NaOH provided. Assume that the concentration of standard solution of NaOH be 0.1M.dm-3 No. of moles of NaOH in 25 cm3 of the solution = 0.0025 moles Since the mole ratio of acid : alkali is 1:2, No. of moles of acid required to neutralize 25 cm3 of the solution of Na OH = 0.0025/2 =0.00125 moles Assuming the n=3, Mr of succinic acid =132 Since Mr = m / M, the mass of succinic acid required = 132*0.00125 = 1.65g. ...read more.
Middle
* Add three drops of phenolphthalein indicator to NaOH. The solution turns pink. * Rinse a clean dry burette with acid solution * The burette is placed on the stand, making sure it is vertical and then fill with the acid solution using a funnel up to about 2cm3 above the 0.00cm3 level. * Run acid through the tap to remove air. Keep the upper level of the acid exactly at the 0.00cm3 level without parallax error. * Open the tap of the burette slowly so that the acid drips into the conical flask * Observe the conical flask constantly while stirring and observe the colour change (changes from pink to colourless) * Towards the end point add acid slowly drop by drop until a single drop makes the alkali completely colourless * Repeat the titration until concordant results ( within � 0.05 cm3) are obtained * Record the initial reading and final reading for each titration and the titration volume is derived Results: An example of burette readings is given below: Burette reading 1 2 3 4 Final volume ( cm3) ...read more.
Conclusion
0.05 cm3 2. There may be zero error for the weighing balance. 3. The perfect verticality of the burette may not be assured 4. The first appearance of the colorless mixture may be missed during the titration. The assessment of the exact colour of the mixture may be hindered by poor or artificial light. Hazards and Safety Hazard Effect Precaution/ prevention Emergency treatment Spillage of the acid or alkali on the skin Corrosive 1.Handle the solutions with great care 2. Wear lab coat and gloves all the time 1. Irrigation of the affected area with plenty of cold water Spillage of alkali on the mucous membrane of mouth while pipetting corrosive Avoid using mouth to fill the pipette. Use filler Gargle with cold water. Seek medical help Inhalation of fumes of the acid or alkali Injury to respiratory tract Avoid inhalation Seek urgent medical help Fumes in the eyes Injury to eye Use goggles all the time Irrigation of eyes with cold water in plenty. Seek medical help if irritation or redness persists. Large spillage of acid or alkali on the floor Damage to floor Careful handling of the equipment Dilute the acid or alkali with plenty of water and mop later. ******************************************** ...read more.
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