Analytical Chemistry with Professional Lab Experiments
Discover comprehensive laboratory procedures, precise calculations, and statistical analysis techniques that transform students into analytical chemistry experts.
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Complete Analytical Chemistry Lab Experiments
Statistical Evaluation & Q-Test
Statistical evaluation of analytical data with Dean and Dixon Q-test for outlier detection using repeated weight measurements.
Required Chemicals & Equipment:
- • Five rupee coins (5 pieces)
- • Analytical balance (±0.0001g)
- • Calculator for statistical analysis
Procedure:
- 1. Weigh each coin 5 times using analytical balance
- 2. Record all measurements in data table
- 3. Calculate mean, standard deviation, and relative standard deviation
- 4. Apply Q-test: Q = |suspect value – nearest value| / range
- 5. Compare calculated Q with critical Q value (0.710 for n=5)
Sample Calculation:
Weights: 3.85g, 3.87g, 3.86g, 3.84g, 3.92g
Mean = 3.868g
Q = |3.92 – 3.87| / (3.92 – 3.84) = 0.625
Since Q < 0.710, no outlier exists
Glassware Calibration
Precise calibration of burette, pipette, and volumetric flask with error analysis and uncertainty calculations.
Required Equipment:
- • 50 mL burette
- • 25 mL pipette
- • 250 mL volumetric flask
- • Distilled water
- • Analytical balance
Calibration Procedure:
- 1. Fill glassware with distilled water at 20°C
- 2. Weigh delivered water using analytical balance
- 3. Convert mass to volume using water density (0.9982 g/mL at 20°C)
- 4. Calculate percentage error: [(Actual – Nominal)/Nominal] × 100
- 5. Repeat measurements 5 times for statistical analysis
Error Calculation:
For 25 mL pipette:
Mass of water = 24.95g
Volume = 24.95/0.9982 = 25.00 mL
Error = [(25.00-25.00)/25.00] × 100 = 0.00%
Standard Solution Preparation
Preparation of molar, normal, and ppm solutions of oxalic acid, NaOH, HCl, and H₂SO₄ with precise calculations.
Required Chemicals:
- • Oxalic acid dihydrate (H₂C₂O₄·2H₂O)
- • Sodium hydroxide pellets (NaOH)
- • Hydrochloric acid (HCl, 37%)
- • Sulfuric acid (H₂SO₄, 98%)
- • Distilled water
Preparation Steps:
- 1. Calculate required mass/volume using molarity formula
- 2. Weigh solid reagents using analytical balance
- 3. Dissolve in small amount of distilled water
- 4. Transfer to volumetric flask and dilute to mark
- 5. Mix thoroughly and label properly
Sample Calculation (0.1M Oxalic Acid):
Molecular weight = 126.07 g/mol
For 250 mL: Mass = 0.1 × 0.25 × 126.07 = 3.15g
Weigh 3.15g oxalic acid dihydrate
NaOH Standardization
Standardization of sodium hydroxide (secondary standard) against oxalic acid (primary standard) using acid-base titration.
Required Solutions:
- • 0.1M Oxalic acid (primary standard)
- • ~0.1M NaOH solution (to be standardized)
- • Phenolphthalein indicator
- • Distilled water
Titration Procedure:
- 1. Pipette 25 mL oxalic acid into conical flask
- 2. Add 2-3 drops phenolphthalein indicator
- 3. Fill burette with NaOH solution
- 4. Titrate until permanent pink color appears
- 5. Record burette readings and repeat 3 times
Calculation:
H₂C₂O₄ + 2NaOH → Na₂C₂O₄ + 2H₂O
M₁V₁/n₁ = M₂V₂/n₂
M(NaOH) = (0.1 × 25 × 2)/(V(NaOH) × 1)
Sodium Chloride Analysis
Quantitative determination of sodium chloride percentage in sample mixtures using precise acid-base titration methods.
Required Materials:
- • Unknown NaCl sample mixture
- • Standardized 0.1M AgNO₃ solution
- • K₂CrO₄ indicator (5%)
- • Distilled water
Analysis Procedure:
- 1. Weigh accurately 0.5-1.0g sample
- 2. Dissolve in 50 mL distilled water
- 3. Add 1 mL K₂CrO₄ indicator
- 4. Titrate with AgNO₃ until brick-red precipitate forms
- 5. Calculate NaCl percentage from titration volume
Percentage Calculation:
NaCl + AgNO₃ → AgCl + NaNO₃
% NaCl = (M × V × 58.44 × 100)/(Sample weight × 1000)
Where M = Molarity of AgNO₃, V = Volume used
Aspirin Content Analysis
Accurate determination of aspirin content in Disprin tablets using back-titration with standardized acid-base solutions.
Required Solutions:
- • Disprin tablets
- • Standardized 0.1M NaOH
- • Standardized 0.1M HCl
- • Phenolphthalein indicator
- • Ethanol (for dissolution)
Back-Titration Method:
- 1. Crush and weigh one Disprin tablet accurately
- 2. Add excess 0.1M NaOH (50 mL) and heat gently
- 3. Cool and add phenolphthalein indicator
- 4. Back-titrate excess NaOH with 0.1M HCl
- 5. Calculate aspirin content from consumed NaOH
Aspirin Calculation:
C₉H₈O₄ + NaOH → C₉H₇O₄Na + H₂O
Moles NaOH consumed = (50 × 0.1) – (V(HCl) × 0.1)
Aspirin mass = Moles × 180.16 g/mol
Water Hardness Determination
Complexometric determination of total hardness (Ca²⁺ + Mg²⁺) in water samples using EDTA as complexing agent.
Required Reagents:
- • Water samples (tap, well, distilled)
- • 0.01M EDTA solution
- • Eriochrome Black T indicator
- • NH₃-NH₄Cl buffer (pH 10)
Complexometric Procedure:
- 1. Take 50 mL water sample in conical flask
- 2. Add 5 mL buffer solution (pH 10)
- 3. Add 2-3 drops Eriochrome Black T indicator
- 4. Titrate with EDTA until blue color appears
- 5. Calculate hardness as mg/L CaCO₃ equivalent
Hardness Calculation:
Hardness (mg/L as CaCO₃) = (V(EDTA) × M(EDTA) × 100.09 × 1000)/V(sample)
Where 100.09 = Molecular weight of CaCO₃
Chloride by Mohr’s Method
Precise determination of chloride content in water samples using Mohr’s argentometric titration method with visual endpoint detection.
Required Solutions:
- • Water samples for analysis
- • Standardized 0.1M AgNO₃ solution
- • 5% K₂CrO₄ indicator solution
- • Distilled water for dilution
Mohr’s Titration Steps:
- 1. Take 50 mL water sample (pH 6.5-10.5)
- 2. Add 1 mL K₂CrO₄ indicator
- 3. Titrate with AgNO₃ until persistent brick-red color
- 4. Record endpoint volume accurately
- 5. Calculate chloride concentration in mg/L
Chloride Calculation:
Cl⁻ + AgNO₃ → AgCl + NO₃⁻
Chloride (mg/L) = (V(AgNO₃) × M(AgNO₃) × 35.45 × 1000)/V(sample)
Where 35.45 = Atomic weight of Cl
Calcium in Gluconate Injection
Quantitative analysis of calcium content in pharmaceutical calcium gluconate injection using EDTA complexometric titration.
Key Calculation:
Ca²⁺ + EDTA⁴⁻ → [Ca-EDTA]²⁻
Ca content (mg/mL) = (V(EDTA) × M(EDTA) × 40.08)/V(injection)
Gravimetric Copper Analysis
Gravimetric determination of copper as cupric oxide (CuO) from unknown samples containing copper metal with precision weighing.
Gravimetric Factor:
Cu → CuO (heating in air)
% Cu = (Weight of CuO × 63.55)/(79.55 × Sample weight) × 100
Gravimetric factor = 63.55/79.55 = 0.7989