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What is Temporary Hardness of Water (removable hardness)?
Grade Level:
Class 6
Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics
Definition
What is it?
Temporary hardness in water means the water contains certain dissolved minerals, mainly bicarbonates of calcium and magnesium, which make it 'hard'. This type of hardness is called 'temporary' because it can be easily removed by simple methods like boiling the water.
Simple Example
Quick Example
Imagine you are trying to wash clothes with soap in two different buckets of water. In one bucket, the soap forms lots of bubbles and lather easily. In the other bucket, it's hard to get much lather, and you see a white, sticky scum instead. The water in the second bucket likely has temporary hardness. If you boil that 'hard' water and then try again, you'll find the soap lathers much better!
Worked Example
Step-by-Step
Let's say you have 1 litre of hard water from a borewell.
Step 1: You take 1 litre of this hard water in a clean steel vessel.
---Step 2: You place the vessel on a gas stove and bring the water to a boil. Let it boil for about 10-15 minutes.
---Step 3: After boiling, you will notice some white deposits (like a thin film or small particles) settling at the bottom of the vessel as the water cools.
---Step 4: Carefully pour the water into another vessel, leaving the white deposits behind. This poured water is now 'softened' water.
---Step 5: If you try to wash your hands with soap in the original hard water, it won't lather well. But with the boiled and decanted water, the soap will lather much more easily, showing that the hardness has been removed.
---Answer: Boiling effectively removed the temporary hardness from the water.
Why It Matters
Understanding water hardness is crucial for industries like HealthTech, where pure water is needed for medicines, and in our homes for health and hygiene. Engineers in Chemistry and Physics use this knowledge to design water purification systems, ensuring we have safe drinking water. It helps us save soap and protect our plumbing.
Common Mistakes
MISTAKE: Thinking all hard water is the same and can be removed by boiling. | CORRECTION: Only temporary hardness can be removed by boiling. Permanent hardness requires different chemical treatments.
MISTAKE: Believing the white deposits after boiling are dirt from the water. | CORRECTION: The white deposits are calcium carbonate and magnesium hydroxide, which are the minerals that caused the temporary hardness, now solidified.
MISTAKE: Confusing temporary hardness with water pollution. | CORRECTION: Temporary hardness is due to naturally dissolved minerals, not necessarily pollution. While it can cause issues, it's different from harmful pollutants.
Practice Questions
Try It Yourself
QUESTION: What are the main minerals responsible for temporary hardness in water? | ANSWER: Bicarbonates of calcium and magnesium.
QUESTION: Your mother complains that her new electric kettle is getting a white coating inside very quickly. What kind of water hardness is likely causing this, and how can she easily remove the coating? | ANSWER: Temporary hardness is causing the white coating (limescale). She can remove it by boiling water with some vinegar or lemon juice, or simply by boiling and then scrubbing.
QUESTION: A family living in a village uses borewell water for all their needs. They notice their clothes are not getting clean easily even with a lot of soap, and their cooking vessels have white marks after boiling water. Explain why this is happening and suggest a simple solution for their drinking water. | ANSWER: This is happening because the borewell water likely has temporary hardness due to dissolved bicarbonates of calcium and magnesium. This prevents soap from lathering and leaves mineral deposits. For their drinking water, a simple solution is to boil the water for 10-15 minutes and then let it cool and settle before carefully pouring it out, leaving the deposits behind.
MCQ
Quick Quiz
Which of the following methods can easily remove temporary hardness from water?
Adding salt
Boiling
Filtering through sand
Freezing
The Correct Answer Is:
B
Boiling causes the dissolved bicarbonates to break down and form insoluble compounds, which then settle down, removing the temporary hardness. Other options like adding salt, filtering, or freezing do not remove these specific dissolved minerals effectively.
Real World Connection
In the Real World
In many Indian households, especially in areas with hard groundwater, people often boil their drinking water. This is not just to kill germs but also to remove temporary hardness, making the water taste better and preventing limescale buildup in kettles and pressure cookers. This simple practice improves water quality for daily use.
Key Vocabulary
Key Terms
HARDNESS: The presence of dissolved mineral ions in water, mainly calcium and magnesium | BICARBONATES: Specific chemical compounds of calcium and magnesium that cause temporary hardness | LATHER: Foamy bubbles produced by soap in water | LIMESCALE: Hard, chalky deposit, mainly calcium carbonate, often found in kettles or pipes due to hard water | BOILING: Heating water to its boiling point to remove temporary hardness
What's Next
What to Learn Next
Great job understanding temporary hardness! Next, you should explore 'What is Permanent Hardness of Water?'. This will teach you about another type of hardness that cannot be removed by boiling, and you'll learn different methods to treat it.
