Kesadahan Air

Summary

This video tutorial covers the process of testing water hardness using volumetric titration. It explains the concept of water hardness, focusing on calcium and magnesium ions, and the difference between temporary and permanent hardness. The procedure includes titration with HCl to measure hardness, the use of indicators like methyl orange, and the necessary chemicals for neutralizing and precipitating. The experiment demonstrates the calculation of hardness in terms of French and German degrees, providing a practical guide for conducting the test and understanding water quality standards.

Takeaways

• 😀 The introduction explains the purpose of the environmental chemistry practical, focusing on water hardness.
• 😀 Water hardness is caused by calcium and magnesium ions, which can react with soap, forming calcium and magnesium salts.
• 😀 The two types of water hardness are temporary (bicarbonate salts) and permanent (chloride and sulfate salts).
• 😀 Temporary hardness can be removed by heating, while permanent hardness cannot be eliminated this way.
• 😀 Water hardness is measured in two units: French degrees (1 part CaCO3 per 100,000 parts water) and German degrees (1 part CaO per 100,000 parts water).
• 😀 The titration method uses 0.1N HCl and the methyl orange indicator to determine the hardness of the water.
• 😀 The maximum permissible limit for water hardness according to the Ministry of Health Regulation is 500 mg/L.
• 😀 Several tools and chemicals are required for the experiment, including burettes, flasks, HCl solution, methyl orange, and NaOH.
• 😀 The process includes preparing the sample, adding indicator, titrating with HCl, and heating the solution to neutralize the acids.
• 😀 The results of the titration are used to calculate the water hardness in both French and German degrees, with results falling within acceptable limits of 500 mg/L.

Q & A

What is water hardness, as explained in the script?

Water hardness refers to the amount of calcium and magnesium ions in water. These ions can react with soap and form calcium and magnesium salts, leading to water hardness.

What are the two main classifications of water hardness?

The two classifications of water hardness are temporary hardness and permanent hardness. Temporary hardness is caused by bicarbonate salts, which can be removed by heating, while permanent hardness is caused by chloride and sulfate salts, which cannot be removed by heating.

How is temporary hardness removed from water?

Temporary hardness is removed by heating the water. For example, calcium bicarbonate is converted into calcium carbonate, which precipitates out of the water.

What are the two types of degrees used to measure water hardness?

The two types of degrees used to measure water hardness are the French degree (°F) and the German degree (°dH). The French degree measures the amount of calcium carbonate in 100,000 parts of water, and the German degree uses calcium oxide as a reference.

What is the standard titration method used to measure water hardness in this experiment?

The standard titration method used in the experiment is volumetric titration with a 0.1 N hydrochloric acid (HCl) solution. The endpoint is detected using methyl orange as an indicator, which changes color from yellow to pink.

What role does methyl orange play in the titration process?

Methyl orange acts as an indicator in the titration process. It changes color from yellow to red when the pH of the solution changes from alkaline to acidic, signaling the endpoint of the titration.

What substances are used to neutralize and precipitate in the hardness testing procedure?

To neutralize the solution, ammonium hydroxide (NH4OH) is used. Sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) are used to precipitate magnesium ions from the solution.

Why is the sample of water heated in the experiment?

The sample is heated to remove temporary hardness by converting calcium bicarbonate into calcium carbonate, which precipitates out and can be separated from the solution.

What does the calculation of hardness involve in this experiment?

The calculation of hardness involves measuring the volume of HCl used in the titration and applying it to specific formulas to calculate hardness in mg/L for both French and German degrees.

What were the final results for the water hardness in the experiment?

The final results for water hardness were 20.5 mg/L for French degree and 11.48 mg/L for German degree, both of which are within the acceptable standard limit of 500 mg/L.