Corrosion and Rancidity play an important role in our daily life. Corrosion and Rancidity are the most popular terms in chemistry of class 9 and class 10 in NCERT book.
We nearly see the phenomenon of corrosion and Rancidity in our surrounding. Let’s use clear with more details. Hi Guys My name is Rishabh and having a experience of more than 10 Years in the field of teaching. Let’s start.
What is Corrosion
Corrosion means degrade or eating of metals by the chemical reaction with water, air, moister, acid and other substance that present in our environment. In corrosion the strength and properties of metal is gradually lose.
Example 1 : Rusting of Iron
Rusting of iron means when iron metal is left over the surrounding then it is react with moisture and water and then a chemical reaction takes place. After it gradually convert in to red-brown substance called Rust.
4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O (Rust)
In other words we say that Corrosion means the metal slowly slowly convert in to other substance and the original metal is not left over.
you can see the below image how it works.
Example 2 : Tarnishing of Silver
we notice that in some time the silver ornaments get a deposition of black substance formed. When silver is kept in surrounding then the silver is react with sulfur compound that is present in air , thus a chemical reaction takes place and forms silver sulfide which is black in color.
This process called Tarnishing of silver or corrosion, where silver metal is convert in to silver sulfide.
4Ag+2H2S+O2→2Ag2S+2H2O
What is Rancidity
Rancidity is the process when fats and oil that present in our food react with oxygen molecule and get oxidize and becomes spoiled. The Spoiled food produce unpleasant smell and bad taste.
The taste of food mostly sour in nature and produce disguise smell.
When we left our foods in open environment then the oil and fats getting oxidizing and make our food spolied.
Examples of Rancidity
Example 1: Chips and Snacks
When we kept the chips and snacks openly in the environment. it slowly become rancid and produce bad smell and taste.
Example 2: Butter
We noticed that when we kept butter outside for long time, it produce odor smell due to rancidity. Hence, we need Refrigerator to prevent from it.
Example 3: Cooking Oil
When we place cooking oil openly then the oxygen molecule fast react with oil and produce disguising smell. It occurs due to Rancidity.
Frequently Asked Questions (FAQs)
Q1. What is corrosion?
Corrosion is the gradually degrade ( eating ) of original metals and convert to other substance.
Q2. What is the most common example of corrosion?
The rusting of iron is the most common example of corrosion as we know that when iron bar is react with moisture and air it forms a layer of Red brown coating called Rust.
Q3. What is rancidity?
Rancidity occurs when foods are place in open place and fats and oils react with oxygen to become spoilage.
Q4. Why do chips become stale after opening the packet?
When chips becomes stale it means that chip are undergo to rancidity. That’s why we kept chip packet in the tight container or nitrogen gas filling container.
Q5. How can corrosion be prevented?
Corrosion can be prevented by many ways such as painting, galvanization, electroplating, and applying oil or grease on it.
Q6. How can rancidity be prevented?
Rancidity can be prevented by refrigeration, airtight containers, vacuum packing, nitrogen filling gas and sometimes using antioxidants.
Q7. Why is nitrogen gas filled in packets of chips?
Nitrogen gas prevents the oxidation of fats and oils and make our food free from becoming rancidity.
Q8. Is rusting a chemical change?
Off Couse, rusting is a chemical change because a new substance called rust ( Red-brown ) is formed.
Q9. Is rancidity a chemical change?
Yes, rancidity is also a chemical change because new substances are fomed but with odor smeel and taste.
Q10. Which process causes economic loss on a large scale?
Corrosion causes huge economic losses because it damages Iron machinery, iron pillars of buildings, Metal bridges, and vehicles. Because metal is slowly eaten up by a chemical reaction with our surrounding.
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