Inorganic Chemistry Lab Experiments

inorganic chemistry lab experiments with detailed calculations

★★★★★
4.8/5 (247 reviews)

🔬 Inorganic Chemistry Lab Complex Preparations

Master the art of inorganic chemistry lab complex synthesis with these essential preparations:

1. Tetraamminecopper (II) Sulphate [Cu(NH₃)₄]SO₄·H₂O

🧪 Detailed Procedure:

  • Step 1: Dissolve 5.0g CuSO₄·5H₂O in 20 mL distilled water in a 250 mL beaker
  • Step 2: Add concentrated NH₃ solution dropwise until deep blue color appears
  • Step 3: Continue adding NH₃ until no further color change occurs (total ~15 mL)
  • Step 4: Add 20 mL ethanol slowly to precipitate the complex
  • Step 5: Filter using Buchner funnel, wash with cold ethanol
  • Step 6: Dry in desiccator for 24 hours

2. Potassium Trioxalatochromate (III) K₃[Cr(C₂O₄)₃]·3H₂O

🧪 Detailed Procedure:

  • Step 1: Dissolve 5.0g K₂Cr₂O₇ in 50 mL water, heat to 60°C
  • Step 2: Add 15g oxalic acid (H₂C₂O₄·2H₂O) slowly with stirring
  • Step 3: Heat mixture to 80°C for 30 minutes until green color develops
  • Step 4: Cool to room temperature, add 10g K₂C₂O₄·H₂O
  • Step 5: Concentrate solution by gentle heating until crystals form
  • Step 6: Filter, wash with ice-cold water, dry in air

3. Potassium Trioxalatoaluminate (III) K₃[Al(C₂O₄)₃]·3H₂O

🧪 Detailed Procedure:

  • Step 1: Dissolve 2.0g Al₂(SO₄)₃·18H₂O in 30 mL hot water
  • Step 2: Add 6.0g oxalic acid dihydrate with continuous stirring
  • Step 3: Heat to 70°C, add 4.0g K₂C₂O₄·H₂O gradually
  • Step 4: Maintain temperature for 45 minutes with stirring
  • Step 5: Cool slowly to allow crystallization
  • Step 6: Filter, wash with cold water, air dry

4. cis-Potassium Dioxalatodiaquachromate (III)

🧪 Detailed Procedure:

  • Step 1: Dissolve 3.0g K₃[Cr(C₂O₄)₃]·3H₂O in 40 mL warm water
  • Step 2: Add 2 mL concentrated HCl dropwise to adjust pH to 2-3
  • Step 3: Heat gently at 50°C for 2 hours with occasional stirring
  • Step 4: Cool in ice bath to promote crystallization
  • Step 5: Filter crystals, wash with ice-cold water
  • Step 6: Dry between filter papers

📊 Comprehensive Calculations

Problem 1: Calculate theoretical yield of [Cu(NH₃)₄]SO₄·H₂O from 5.0g CuSO₄·5H₂O

Reaction: CuSO₄·5H₂O + 4NH₃ → [Cu(NH₃)₄]SO₄·H₂O + 4H₂O
Molar mass CuSO₄·5H₂O = 249.68 g/mol
Molar mass [Cu(NH₃)₄]SO₄·H₂O = 245.74 g/mol
Moles CuSO₄·5H₂O = 5.0g ÷ 249.68 = 0.0200 mol
Theoretical yield = 0.0200 mol × 245.74 g/mol = 4.92g

Problem 2: Calculate percentage yield if actual yield is 4.15g

Percentage yield = (Actual yield ÷ Theoretical yield) × 100
Percentage yield = (4.15g ÷ 4.92g) × 100 = 84.3%

Problem 3: Calculate molarity of NH₃ solution if 15 mL is used

Moles NH₃ required = 4 × 0.0200 = 0.0800 mol
Molarity = 0.0800 mol ÷ 0.015 L = 5.33 M

⚖️ Complexometric Titration Analysis

Perfect your analytical skills with complexometric titration techniques:

1. Determination of Zinc by EDTA Titration

🧪 Detailed Procedure:

  • Step 1: Prepare 0.01 M EDTA solution by dissolving 3.72g Na₂H₂EDTA·2H₂O in 1L water
  • Step 2: Standardize EDTA using 0.01 M ZnSO₄ standard solution
  • Step 3: Pipette 25.0 mL unknown Zn²⁺ solution into conical flask
  • Step 4: Add 5 mL NH₃-NH₄Cl buffer (pH 10) to maintain alkaline conditions
  • Step 5: Add 2-3 drops Eriochrome Black T indicator (wine red color)
  • Step 6: Titrate with EDTA until color changes from wine red to blue
  • Step 7: Record burette reading and repeat for concordant values

2. Determination of Cadmium by EDTA Titration

🧪 Detailed Procedure:

  • Step 1: Use same standardized EDTA solution from zinc determination
  • Step 2: Pipette 25.0 mL unknown Cd²⁺ solution into conical flask
  • Step 3: Add 10 mL NH₃-NH₄Cl buffer to maintain pH at 10
  • Step 4: Add 2-3 drops Eriochrome Black T indicator
  • Step 5: Titrate slowly with EDTA solution near endpoint
  • Step 6: Endpoint: wine red to blue color change
  • Step 7: Calculate cadmium concentration using 1:1 stoichiometry

3. Buffer Preparation (NH₃-NH₄Cl, pH 10)

🧪 Detailed Procedure:

  • Step 1: Dissolve 67.5g NH₄Cl in 200 mL distilled water
  • Step 2: Add 570 mL concentrated NH₃ solution slowly with stirring
  • Step 3: Dilute to 1000 mL with distilled water
  • Step 4: Check pH using pH meter (should be 10.0 ± 0.1)
  • Step 5: Store in plastic bottle, label clearly

🧮 Comprehensive Titration Calculations

Problem 1: 25.0 mL Zn²⁺ solution requires 18.5 mL of 0.0250 M EDTA. Find [Zn²⁺]

Reaction: Zn²⁺ + EDTA⁴⁻ → [Zn(EDTA)]²⁻
Moles EDTA = 0.0185 L × 0.0250 M = 4.625 × 10⁻⁴ mol
Moles Zn²⁺ = Moles EDTA (1:1 ratio) = 4.625 × 10⁻⁴ mol
[Zn²⁺] = 4.625 × 10⁻⁴ mol ÷ 0.0250 L = 0.0185 M

Problem 2: Calculate mass of Zn²⁺ in 250 mL solution if [Zn²⁺] = 0.0185 M

Total moles Zn²⁺ = 0.0185 M × 0.250 L = 4.625 × 10⁻³ mol
Mass Zn²⁺ = 4.625 × 10⁻³ mol × 65.38 g/mol = 0.302 g

Problem 3: If 20.0 mL Cd²⁺ requires 15.8 mL of 0.0250 M EDTA, find [Cd²⁺]

Moles EDTA = 0.0158 L × 0.0250 M = 3.95 × 10⁻⁴ mol
Moles Cd²⁺ = 3.95 × 10⁻⁴ mol (1:1 ratio)
[Cd²⁺] = 3.95 × 10⁻⁴ mol ÷ 0.0200 L = 0.0198 M

Problem 4: Calculate percentage of Zn in brass sample (0.5000g) if titration shows 0.0185 M Zn²⁺

Mass of Zn = 0.302 g (from Problem 2)
% Zn = (0.302 g ÷ 0.5000 g) × 100 = 60.4%

📋 Chromatographic Separations Excellence

Master paper chromatography techniques for transition metal separation:

1. Separation of Ni²⁺ & Co²⁺ Ions

🧪 Detailed Procedure:

  • Step 1: Prepare mobile phase: Acetone:HCl:H₂O (90:3:7 v/v/v)
  • Step 2: Cut Whatman No.1 filter paper (20×15 cm), draw pencil line 2 cm from bottom
  • Step 3: Prepare sample: Mix equal volumes of 0.1 M NiCl₂ and 0.1 M CoCl₂
  • Step 4: Apply 2-3 drops of sample mixture on pencil line using capillary tube
  • Step 5: Allow spot to dry completely, repeat application 2-3 times
  • Step 6: Place paper in chromatography chamber with mobile phase
  • Step 7: Allow solvent to rise 12-15 cm, remove and air dry
  • Step 8: Spray with 1% dimethylglyoxime in ethanol to detect Ni²⁺ (red spots)
  • Step 9: Spray with 1% nitroso-R-salt to detect Co²⁺ (orange-red spots)

2. Separation of Ni²⁺ & Cu²⁺ Ions

🧪 Detailed Procedure:

  • Step 1: Prepare mobile phase: Butanol:Acetic acid:H₂O (4:1:1 v/v/v)
  • Step 2: Use same paper preparation as above
  • Step 3: Prepare sample: Mix 0.1 M NiSO₄ and 0.1 M CuSO₄ solutions
  • Step 4: Apply sample mixture, dry thoroughly
  • Step 5: Develop chromatogram for 3-4 hours
  • Step 6: Remove paper, mark solvent front immediately
  • Step 7: Cu²⁺ appears blue-green, Ni²⁺ appears pale green
  • Step 8: Confirm with specific reagents: NH₃ for Cu²⁺, DMG for Ni²⁺

3. Separation of Cu²⁺ & Fe³⁺ Ions

🧪 Detailed Procedure:

  • Step 1: Prepare mobile phase: Acetone:HCl (9:1 v/v)
  • Step 2: Prepare sample: Mix 0.1 M CuCl₂ and 0.1 M FeCl₃ solutions
  • Step 3: Apply sample on filter paper baseline
  • Step 4: Develop chromatogram in closed chamber
  • Step 5: Fe³⁺ moves faster (higher Rf) than Cu²⁺
  • Step 6: Detect Fe³⁺ with K₄[Fe(CN)₆] solution (blue spots)
  • Step 7: Detect Cu²⁺ with K₄[Fe(CN)₆] solution (brown spots)
  • Step 8: Calculate Rf values for identification

4. Detection Reagents Preparation

🧪 Detailed Procedure:

  • Dimethylglyoxime (DMG): Dissolve 1g DMG in 100 mL ethanol
  • Potassium ferrocyanide: Dissolve 1g K₄[Fe(CN)₆] in 100 mL water
  • Nitroso-R-salt: Dissolve 0.5g in 100 mL water, add 2 drops HCl
  • Ammonia solution: Dilute concentrated NH₃ to 2 M concentration

📏 Comprehensive Rf Calculations

Problem 1: Cu²⁺ spot travels 4.2 cm, solvent front moves 5.8 cm. Calculate Rf

Rf = Distance traveled by solute ÷ Distance traveled by solvent
Rf(Cu²⁺) = 4.2 cm ÷ 5.8 cm = 0.72

Problem 2: In Ni²⁺/Co²⁺ separation: Ni²⁺ = 2.1 cm, Co²⁺ = 3.8 cm, solvent = 6.2 cm

Rf(Ni²⁺) = 2.1 cm ÷ 6.2 cm = 0.34
Rf(Co²⁺) = 3.8 cm ÷ 6.2 cm = 0.61
Separation factor (α) = Rf(Co²⁺) ÷ Rf(Ni²⁺) = 0.61 ÷ 0.34 = 1.79

Problem 3: Calculate resolution (Rs) if peak widths are 0.8 cm and 0.6 cm

Distance between centers = 3.8 – 2.1 = 1.7 cm
Average peak width = (0.8 + 0.6) ÷ 2 = 0.7 cm
Rs = 1.7 ÷ 0.7 = 2.43 (excellent separation, Rs > 1.5)

Problem 4: If Fe³⁺ travels 5.1 cm and Cu²⁺ travels 3.2 cm with solvent front at 6.8 cm

Rf(Fe³⁺) = 5.1 ÷ 6.8 = 0.75
Rf(Cu²⁺) = 3.2 ÷ 6.8 = 0.47
ΔRf = 0.75 – 0.47 = 0.28 (good separation)

🌈 Spectrophotometric Determination Mastery

Excel in spectrophotometric determination of transition metals:

1. Iron Determination using 1,10-Phenanthroline

🧪 Detailed Procedure:

  • Step 1: Prepare 0.1% 1,10-phenanthroline solution in distilled water
  • Step 2: Prepare acetate buffer (pH 4.5): Mix CH₃COONa and CH₃COOH solutions
  • Step 3: Prepare hydroxylamine hydrochloride (10%) to reduce Fe³⁺ to Fe²⁺
  • Step 4: Take 25 mL unknown iron solution in 100 mL volumetric flask
  • Step 5: Add 2 mL hydroxylamine solution, mix well
  • Step 6: Add 5 mL acetate buffer to maintain pH
  • Step 7: Add 3 mL phenanthroline solution, mix thoroughly
  • Step 8: Dilute to mark with distilled water, allow 10 minutes for color development
  • Step 9: Measure absorbance at 510 nm against blank
  • Step 10: Prepare standard curve using known Fe²⁺ concentrations

2. Manganese Determination using Periodate Oxidation

🧪 Detailed Procedure:

  • Step 1: Prepare 0.1 M KIO₄ solution in distilled water
  • Step 2: Prepare phosphoric acid solution (1:1 H₃PO₄:H₂O)
  • Step 3: Take 25 mL unknown manganese solution in 100 mL volumetric flask
  • Step 4: Add 10 mL phosphoric acid solution
  • Step 5: Add 5 mL KIO₄ solution to oxidize Mn²⁺ to MnO₄⁻
  • Step 6: Heat gently at 60°C for 15 minutes
  • Step 7: Cool to room temperature, dilute to mark
  • Step 8: Measure absorbance at 525 nm (purple MnO₄⁻ color)
  • Step 9: Use molar absorptivity ε = 2,230 L·mol⁻¹·cm⁻¹

3. Nickel Determination using Dimethylglyoxime

🧪 Detailed Procedure:

  • Step 1: Prepare 1% dimethylglyoxime in ethanol
  • Step 2: Prepare ammonia buffer (pH 9): NH₃-NH₄Cl solution
  • Step 3: Take 25 mL unknown nickel solution in 100 mL volumetric flask
  • Step 4: Add 10 mL ammonia buffer to maintain alkaline pH
  • Step 5: Add 5 mL dimethylglyoxime solution dropwise
  • Step 6: Mix well, allow 30 minutes for complex formation
  • Step 7: Dilute to mark with distilled water
  • Step 8: Measure absorbance at 445 nm (yellow-green complex)
  • Step 9: Prepare calibration curve with standard Ni²⁺ solutions

4. Standard Solutions Preparation

🧪 Detailed Procedure:

  • Iron stock (1000 ppm): Dissolve 7.022g Fe(NH₄)₂(SO₄)₂·6H₂O in 1L water
  • Manganese stock (1000 ppm): Dissolve 3.076g MnSO₄·H₂O in 1L water
  • Nickel stock (1000 ppm): Dissolve 4.478g NiSO₄·6H₂O in 1L water
  • Working standards: Dilute stock solutions to 1, 2, 5, 10, 20 ppm

💡 Comprehensive Spectrophotometric Calculations

Problem 1: Iron solution shows absorbance 0.485 at 510 nm. If ε = 11,100 L·mol⁻¹·cm⁻¹, find concentration

Beer-Lambert Law: A = εbc
c = A ÷ (ε × b)
c = 0.485 ÷ (11,100 × 1.0) = 4.37 × 10⁻⁵ M
Mass concentration = 4.37 × 10⁻⁵ × 55.85 = 2.44 mg/L

Problem 2: Manganese shows A = 0.325 at 525 nm. Calculate [Mn] if ε = 2,230 L·mol⁻¹·cm⁻¹

c = A ÷ (ε × b)
c = 0.325 ÷ (2,230 × 1.0) = 1.46 × 10⁻⁴ M
[Mn] in mg/L = 1.46 × 10⁻⁴ × 54.94 = 8.02 mg/L

Problem 3: Calibration curve for Ni: A = 0.0485c + 0.008. If sample A = 0.245, find [Ni]

A = mc + b (linear calibration)
0.245 = 0.0485c + 0.008
c = (0.245 – 0.008) ÷ 0.0485 = 4.89 mg/L

Problem 4: Calculate detection limit if blank A = 0.005 ± 0.002, slope = 0.0485

Detection limit = 3 × standard deviation ÷ slope
DL = 3 × 0.002 ÷ 0.0485 = 0.124 mg/L

Problem 5: If dilution factor is 10 and final [Fe] = 2.44 mg/L, find original concentration

Original concentration = Final concentration × Dilution factor
Original [Fe] = 2.44 × 10 = 24.4 mg/L

🔗 External References

For additional theoretical background, visit RSC Periodic Table and NIST Chemistry WebBook for comprehensive spectroscopic data.

Advanced techniques: Shimadzu Analysis Basics and Agilent Spectroscopy Resources

🚀 Explore More Amazing Science Topics

Expand your scientific knowledge with our comprehensive study materials

🧪 Explore Chemistry 🧬 Discover Biology ⚡ Master Physics 🔬 Study Biochemistry