chem lab manual

Page 1: Standardization of EDTA

• Experiment Details:

  • Date:

  • Department of Chemistry

  • Name:

  • Branch:

  • Registration Number:

  • Duration: 90 min

• Objective: Standardization of EDTA by titrating against standard hard water.

• Requirements:

  • Reagents and Solutions:

    • Standard hard water (0.01M or 1000ppm)

    • EDTA solution

    • EBT indicator

    • NH3-NH4Cl buffer solution

  • Apparatus:

    • Burette

    • Pipette

    • Conical flask

    • Standard flask

    • Burette stand

• Procedure:

  1. Prepare EDTA solution:

     • Add distilled water to 100 mL in a volumetric flask.

  2. Titration Setup:

     • Pipette 20 mL of standard hard water into a conical flask.

     • Add 2 mL of NH4OH-NH4Cl buffer (to maintain pH ~10).

     • Add 1-2 drops of EBT indicator.

  3. Titration:

     • Titrate against the EDTA solution until color changes from wine red to steel blue.

     • Record volume of EDTA used as 'V1'.

  4. Replicate: Repeat for concordant readings.

• Data Table:

  S.No	Volume of standard hard water (mL)	Burette reading (mL)	Volume of EDTA (V1, mL)
  1
  2
  3

• Calculation:

  • ( 1 \text{ mL of EDTA} = \left( \frac{20}{V1} \right) \text{ mg of CaCO3 eq.} )

Page 2: Calculation of Molarity of EDTA

• (Expression of Concentration):

  • Given M1V1 = M2V2, with M1 for EDTA, M2 for CaCO3.

• Calculations:

  • ( M1 = \frac{M2 \times V2}{V1} = \frac{0.01 \times 20}{V1} ) (Molarity of CaCO3)

  • Equivalence Data:

    • 1L of 1M EDTA = 100g eqvt. of CaCO3

    • 1L of 0.01 x 20/ V1 EDTA = ( \frac{20}{V1} \text{ gm eq. of CaCO3} )

• Result Evaluation:

  • Sample water: 50mL of tap water required 15mL of EDTA.

  • After boiling, 10mL of EDTA consumed for same sample.

  • 50mL of 0.02M standard CaCO3 consumed 20mL of EDTA.

• Calculate hardness (temporary, permanent, total) in ppm.

Page 3: Determination of Total Hardness

• Aim: To determine total hardness of water using EDTA complexometric titration.

• Principle: Hardness arises from Ca2+ and Mg2+ salts in the water.

  • Reaction:

    • EDTA forms complexes with cations, quantitatively at pH 10.

    • General reaction: ( M + H2Y2- \rightarrow MY2- + 2H+ ) wherein M = Ca2+, Mg2+.

    • EBT forms a wine-red complex with M2+, less stable than metal-EDTA.

• Requirements:

  • Reagents/Solutions:

    • Standard hard water (0.01M), EDTA, EBT indicator, NH3-NH4Cl buffer

  • Apparatus: Same as previous.

Page 4: Procedure for Hardness Estimation

• Procedure for Titration I (Standardization of EDTA):

  1. Prepare a 100 mL EDTA solution for titration.

  2. Pipette 20 mL of standard calcium ion solution into a conical flask.

  3. Add 2-3 mL NH4OH-NH4Cl buffer and 3 drops of EBT.

  4. Titrate with EDTA until the color changes from red to blue: record as 'V1'.

• Procedure for Titration II (Total Hardness Estimation):

  1. Pipette 20 mL of the water sample into a conical flask.

  2. Follow steps 2-4 from Titration I, recording as 'V2'.

• Observation and Calculation:

  • Titration I Data Table:

  S.No	Volume of standard hard water (mL)	Burette reading (mL)	Volume of EDTA (V1, mL)
  1
  2
  3

  • Calculate hardness from V1 and V2.

Page 5: Titration II - Estimation of Total Hardness

• Burette: Standard EDTA solution

• Conical Flask: 20 mL of hard water + buffer + 2 drops of EBT

• Data Table:

  S.No	Volume of standard hard water (mL)	Burette reading (mL)	Volume of EDTA (V2, mL)
  1
  2
  3

• From this measurement, define total hardness in ppm.

Page 6: Estimation of Alkalinity in Wastewater

• Aim: Determine types and extent of alkalinity in a water sample.

• Principle: Alkalinity from OH-, CO32-, HCO3- ions neutralized by standard HCl.

• Detection Metrics:

  1. Titrate until pH 8.3 (Phenolphthalein indicator) = neutralizes OH- and half CO32-.

  2. Titrate until 4.4 (Methyl Orange indicator) = total alkalinity measured.

• Reagents/Solutions:

  • Hydrochloric acid (0.1N)

  • Methyl orange & phenolphthalein indicators

• Procedure:

  1. Mix water sample in a 100 mL volumetric flask and add HCl till the endpoint records [P] and [T].

  2. Record readings for subsequent calculations.

• Calculation Table:

  S.No	Water Sample (mL)	Burette Reading at [P] (mL)	Burette Reading at [T] (mL)

• Results: Determine the concentrations of each ion as well as total alkalinity.

Page 7: Estimation of Alkalinity - Observations and Calculations

• Titration Observation Table:

  S.No	Volume of Water Sample (mL)	Burette Reading (mL)	Concordant Value (mL)
  1

• Phenolphthalein Alkalinity and Calculations:

  • ( ext{Phenolphthalein Alkalinity (mg/L as CaCO3)} = \text{mL of HCl} \times \text{Normality of HCl} \times 50 \times 1000 )
    

• Methyl Orange Alkalinity Calculations: ( ext{Methyl Orange Alkalinity (mg/L as CaCO3)} = \text{mL of HCl} \times \text{Normality of HCl} \times 50 \times 1000 )

Page 8: Alkalinity Summary

• Data Regarding OH-, CO32-, HCO3- Alkalinity Types:

• Results Evaluation:

  • Total alkalinity and data to be filled:

  • Sample number, experimental values, actual values, % error, marks, and space for calculations.

Page 9: Estimation of Copper in Alloy by Iodometry

• Aim: To estimate copper content in a sample solution.

• Principle: Reaction of iodine and sodium thiosulphate and subsequent titration.

• Reagents/Solutions:

  • 0.01 N copper sulphate, KI, 0.01N sodium thiosulphate.

• Procedure Titration I (Standardization):

  1. Pipette 20ml of copper sulphate into a conical flask.

  2. Add ammonium hydroxide till precipitate forms, then clear it with acetic acid.

  3. Add KI and titrate iodine against thiosulphate until blue disappears.

• Data Table for Titration Analysis:| S.No | Volume of Std CuSO4 (ml) | Final Burette Reading | Volume of Sodium Thiosulphate (ml) |

Page 10: Estimation of Copper - Observations

• Titration II:

  1. Make alloy to 100 mL solution, and process as above.

  2. Measure readings.

• Data for Analysis:| S.No | Volume of Unknown CuSO4 (ml) | Volume of Sodium Thiosulphate (ml) |

• Calculate copper using: ( ext{Cu (present in the solution)} = \frac{ ext{Normality} \times ext{Equivalent Weight}}{10} )

Page 11 to 15:

• Calculations

• Detailed observation values across experiments, results, and marks analysis.

• Equivalence and final outcomes in standard measurements.

Page 16: Dissolved Oxygen Analysis

• Aim: Estimate dissolved oxygen in water samples via Winkler’s method.

• Principle: Oxygen oxidation of potassium iodide, measured via thiosulphate titration.

• Procedure:

  1. Mix sample with reagents, precipitate settling, then titrate.

  2. Record and calculate dissolved oxygen (ppm).

Page 17: Results Calculation of DO

• Formula Usage: ( ext{ppm} = N \times ext{equivalent weight} \times 1000 mg/L ) where N is normality.

Page 18: Estimation of Sulphate in Effluent

• Principle: Conductometric method evaluates the ion presence through conductivity variations during titration.

• Procedure:

  1. Calibrate TDS meter with KCl.

  2. Follow through with BaCl2 to monitor conductance.

• Data Recording and Graphing:

  • Result interpretation from graphs reflecting BaCl2 additions related to sulphate levels.

Pages 19-20: Data Analysis and Calculations in Sulphate Assessment

• Concise tabulated data reflecting volumetric analysis results.

Page 21: Fe(II) Estimation by Redox Potentiometry

• Principle: Potassium permanganate oxidizes ferrous ions under controlled conditions.

• Procedure: Measure EMF changes corresponding to titration volume; determine iron concentration from graphs.

Pages 22-24: Potentiometric Methods and Result Compilation

• Calculation equations for assessing Fe(II) concentration, aimed around titration endpoints with proper data layout for observations.

Page 25: Colorimetric Estimation of Copper in Brass

• Principle and Procedures:

  • Apply Beer's law to colorimetric analysis for Cu concentrations.

  • Prepare standard solutions and measure absorbances, graph results.

• Final Results: Reports for concentration outputs, comparative calculations.