PROCEDURE PART ONE: Preparation of a Standard Beer\'s Law Curve: 1. Weigh accura
ID: 517802 • Letter: P
Question
PROCEDURE PART ONE: Preparation of a Standard Beer's Law Curve: 1. Weigh accurately 0.4 g of acetylsalicylic acid into a 250 ml Erlenmeyer flask. 2. Record the mass of the acetylsalicylic acid used. 3. Add 10 ml of 1.0 M sodium hydroxide and heat the mixture to boiling. Care should be exercised to avoid splattering and loss of contents. 4. Rinse down the inside walls of the Erlenmeyer flask with distilled water to ensure quantitative hydrolysis of the acetylsalicylic acid. 5. Quantitatively transfer the resulting solution of sodium salicylate to a 250 ml volumetric flask and dilute to the mark with distilled water. 6. Pipet 5 ml aliquot of this solution into a 100 ml volumetric flask and dilute to the mark with 0.02 M iron (ID chloride solution which has been buffered to a pH of 1.6 with hydrochloric acid-potassium chloride buffer. 7. Similarly, dilute 4-, 3-, 2-, and 1-ml aliquots of the sodium salicylate solution with the iron (I) chloride solution. 8. Determine and record the absorption of each violet solution spectrophotometrically at 530 nm utilizing the iron (Ill chloride buffer solution as a calibration blank.Explanation / Answer
From the above shown reaction data for the hydrolysis of acetyl salicylic acid to sodium salicylate with base sodium hydroxide and then forming complex with Fe(III) solution
Table
Reading concentration of complex (M)
1 0.0088 M x 5 ml/100 ml = 0.00044 M
2 0.0088 M x 4 ml/100 ml = 0.000352 M
3 0.0088 M x 3 ml/100 ml = 0.000264 M
4 0.0088 M x 2 ml/100 ml = 0.000176 M
5 0.0088 M x 1 ml/100 ml = 0.000088 M
Plot, concentration of complex on x-axis and absorbance on y-axis
The slope of the curve gives the molar absorptivity of complex Fe(III)-sodium salicylate formed.
Plot below
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