Chloride Calculator
About Chloride Formula
Chloride (mg/l) = (A-B) × N × 35.45 × 1000 / ml of sample
Where:
- A = ml AgNO₃ required for sample
- B = ml AgNO₃ required for blank
- N = Normality of AgNO₃ used
- 35.45 = Atomic weight of chloride
- 1000 = Conversion factor to mg/l
Chloride Information
Chloride anion is generally present in natural waters and waste waters. The presence of chloride in natural waters can be attributed to dissolution of salt deposits, discharge of effluents from industries, and other anthropogenic sources.
Importance and Significance:
- Water Quality Indicator: Chloride concentration is an important parameter in determining water quality for various uses.
- Taste Impact: The salty taste produced by chloride depends on the chemical composition of the water. A concentration of 250 mg/l may be detectable in water containing sodium ions, while the salty taste may be absent in water containing up to 1000 mg/l chloride when calcium and magnesium ions are predominant.
- Infrastructure Impact: High chloride content has a deleterious effect on metallic pipes and structures due to its corrosive nature.
- Agricultural Impact: Elevated chloride levels can negatively affect agricultural plants, impacting crop yields and quality.
- Environmental Health: Chloride levels can affect aquatic ecosystems and the organisms that live within them.
Standard Ranges and Guidelines:
- Drinking Water: The WHO and many national standards recommend that chloride levels in drinking water should not exceed 250 mg/l.
- Fresh Surface Water: Natural freshwater bodies typically contain chloride levels between 1-100 mg/l.
- Agricultural Use: For irrigation water, chloride levels below 70 mg/l are generally considered safe for most plants, while levels above 350 mg/l can cause severe problems for many crops.
- Industrial Use: Requirements vary by industry, but many industrial processes require water with low chloride content to prevent corrosion and other issues.
Measurement Principle:
Chloride is determined in a natural or slightly alkaline solution by titration with standard silver nitrate, using potassium chromate as an indicator. Silver chloride is quantitatively precipitated before red silver chromate is formed, allowing for accurate determination of the endpoint.
Reagents Required:
- Potassium chromate indicator: Dissolve 50 gm K₂CrO₄ in distilled water. Add AgNO₃ till definite red precipitate is formed. Allow to stand for 12 hours. Filter and dilute to 1000 ml.
- Silver Nitrate 0.0141 N: Dissolve 2.395 gm AgNO₃ and dilute to 1000 ml. Standardize against NaCl, 0.0141 N. 1 ml of 0.0141 N AgNO₃ = 0.5 mg Cl⁻.
- Sodium chloride 0.0141 N: Dissolve 824.1 mg NaCl (dried at 140°C) and dilute to 1000 ml. 1 ml = 0.5 mg Cl⁻.
Procedure:
- Take 100 ml of sample and adjust the pH between 7.0-8.0.
- Take 50 ml of well-mixed sample adjusted to pH 7.0-8.0 and add 1.0 ml K₂CrO₄.
- Titrate with standard AgNO₃ solution till AgCrO₄ starts precipitating.
- Standardize AgNO₃ against std. NaCl.
- For better accuracy, titrate distilled water (50 ml) in the same way to establish reagent blank.
