KVV E-Modules - Estimation of free CO2 from given water sample

Quadrant -I (Video)

Estimation of free CO2 from given water sample

Quadrant - II (Study Material)

1. Estimation of free CO2 from given water sample

View File

Quadrant - III (Assignments)

1. Estimation of free CO2 from given water sample

Free carbon dioxide in the water accumulates due to microbial activity and respiration of microorganisms. Surface water normally contains less than 10mg/L free co2 while some ground water may easily exceed that concentration up to 30-50 mg/L. This imparts acidity to the water because of the formation of carbonic acid. The CO2 content in water may contribute significantly to corrosion.

Download Assignment

Quadrant - IV (MCQs)

What is the main chemical used for titration in the estimation of free CO₂ in water?

A: Hydrochloric acid B: Sodium thiosulfate C: Standard sodium carbonate D: Standard sodium hydroxide

Which indicator is commonly used in the titration process for estimating free CO₂?

A: Methyl orange B: Phenolphthalein C: Bromothymol blue D: Litmus

The endpoint of the titration is indicated by which color change?

A: Red to colorless B: Yellow to pink C: Colorless to pink D: Blue to green

Free carbon dioxide in water exists mainly in which form?

A: CO₂ gas B: Carbonic acid (H₂CO₃) C: Bicarbonate ion (HCO₃⁻) D: Carbonate ion (CO₃²⁻)

Which of the following best describes the reaction during the titration of free CO₂ with NaOH?

A: CO₂ + H₂O → H₂CO₃ B: H₂CO₃ + NaOH → NaHCO₃ + H₂O C: NaHCO₃ → Na₂CO₃ + CO₂ D: CO₂ + NaOH → Na₂CO₃

Why is phenolphthalein used as an indicator in this experiment?

A: It changes color in strongly acidic pH B: It changes color in basic pH C: It is sensitive to pH change around 8.3 D: It detects CO₂ directly

What is the usual volume of the water sample taken for this estimation in a lab setting?

A: 10 mL B: 25 mL C: 50 mL D: 100 mL

Free CO₂ in water contributes to which of the following properties?

A: Alkalinity B: Hardness C: Acidity D: Turbidity

Why must the water sample be analyzed immediately after collection?

A: CO₂ evaporates easily B: NaOH loses strength C: Indicator degrades D: Bacteria consume CO₂

If the pink color appears after adding phenolphthalein, it indicates:

A: No free CO₂ is present B: High free CO₂ content C: The sample is too alkaline D: Acidic sample

Validation Certificates

1. Validation Certificate No. 1

View File

2. Validation Certificate No. 2

View File

3. Validation Certificate No. 3

View File