Hardness of Water | Temporary | Permanent

Summary

This video delves into the concept of water hardness, a property influenced by dissolved calcium and magnesium salts. Hard water fails to lather with soap due to these salts, leading to scum formation. The hardness is categorized into temporary, caused by bicarbonates and carbonates removable by boiling, and permanent, from other salts like sulfates and chlorides, requiring treatments like zeolite or ion exchange for removal. The video promises to explore hardness calculations in subsequent lectures.

Takeaways

• 💧 Water hardness is a property that affects how water interacts with soap, preventing it from lathering properly.
• 🔍 Hard water contains dissolved salts of calcium and magnesium, which are responsible for its hardness.
• 🧼 The inability to lather with soap is a key indicator of water hardness due to the reaction between calcium/magnesium ions and soap's fatty acid salts.
• 🌟 There are two main types of water hardness: temporary and permanent, distinguished by the salts present and their reactivity.
• 🕒 Temporary hardness is caused by bicarbonates and carbonates of calcium and magnesium, which can be removed by boiling the water.
• 🔬 Permanent hardness is due to other salts like chlorides, sulfates, nitrates, and phosphates, which do not remove easily by boiling.
• 🧪 A simple test to identify hard water is by adding soap and observing if a white precipitate, or scum, forms, indicating the presence of hardness.
• 🌡 Boiling water can convert bicarbonates to carbonates, which then precipitate out, thus reducing temporary hardness.
• 🛠 To remove permanent hardness, methods like using zeolite, lime soda process, or ion exchange resins are employed.
• ⏩ The lecture will continue with calculations related to water hardness in the next session.

Q & A

What is water hardness?

Water hardness is a property of water that prevents it from lathering with soap properly due to the presence of dissolved salts of calcium and magnesium.

Why does hard water not lather with soap?

Hard water contains calcium and magnesium salts that react with the sodium or potassium salts of higher fatty acids in soap, leading to the formation of a precipitate or scum, which prevents proper lathering.

What are the two main types of water hardness?

The two main types of water hardness are temporary hardness and permanent hardness.

What causes temporary hardness in water?

Temporary hardness is caused by the presence of bicarbonates and carbonates of calcium and magnesium in the water, which can be removed by boiling.

How can you remove temporary hardness from water?

Temporary hardness can be removed by boiling the water, which causes the bicarbonates and carbonates to convert into precipitates that can be filtered out.

What is permanent hardness and how is it different from temporary hardness?

Permanent hardness is caused by salts other than bicarbonates and carbonates, such as chlorides, sulfates, nitrates, and phosphates of calcium and magnesium, and cannot be removed by boiling alone.

What are some methods to remove permanent hardness from water?

Permanent hardness can be removed using methods like ion exchange, zeolite, or lime soda processes, which involve the use of compounds like zeolite, calcium hydroxide, or sodium carbonate.

Why is it important to identify water hardness?

Identifying water hardness is important to determine the suitability of water for various applications, such as domestic use, agriculture, and industrial processes, where hard water can cause scaling and other issues.

What is pseudo hardness and how does it differ from temporary and permanent hardness?

Pseudo hardness, also known as fake hardness, is not discussed in detail in the script but generally refers to hardness caused by certain metals other than calcium and magnesium, which can be removed by simple settling or filtration.

How can you differentiate between hard and soft water?

Hard water can be identified by its inability to lather with soap and the presence of a white precipitate or scum, while soft water will lather easily and not produce a precipitate.

What are the potential issues caused by hard water in domestic use?

Hard water can cause issues such as scaling in pipes and appliances, reduced efficiency of water heaters, and difficulty in cleaning with soap, which can affect the quality of laundry and dishes.