Science

Dekho — have you ever lit an agarbatti (incense stick) at home for puja? When it burns, you see it change into ash and smoke, and a totally new fragrance fills the air — this means new things have formed! This change, where new substances are created with different properties, is what we call a chemical reaction. What are the indicators that tell you a chemical reaction is happening when an agarbatti burns?

❌ Many students believe that any change they observe, like water boiling or ice melting, is a chemical reaction.

✅ No, that's not quite right. A chemical reaction specifically involves the formation of new substances with completely different properties. Water boiling or ice melting are just physical changes, where the substance's chemical identity remains the same – it's still water, just in a different state. Can you think of another everyday example where a physical change is often confused with a chemical reaction?

Ek kaam karo — take one spoon of baking soda in an empty bottle. Now, add a little vinegar to it and observe carefully. You'll see fizzing, which is a sign of gas evolution, showing a chemical reaction is taking place.

See interactive experiment in app →

You know how sometimes, after eating too much spicy biryani or oily pakoras, you get that burning sensation in your stomach? — We call that 'acidity'. And then your mum might tell you to take some Eno or a 'Digene' tablet. Ever wondered what these antacids actually do? Socho zara — how do these antacids manage to calm down that burning feeling in your stomach?

❌ Oh, acid means dangerous, burns everything! And bases? They're like soap, totally safe.

✅ Dekho beta — that's not quite right. Some acids, like the citric acid in nimbu paani or the acetic acid in vinegar, we actually consume. And on the other hand, some bases, like concentrated sodium hydroxide used in drain cleaners, can be extremely dangerous and can cause severe skin burns. It's all about their 'strength' — whether they are 'strong' or 'weak'. So — how do you think scientists categorize acids and bases as 'strong' or 'weak'?

Ek kaam karo — take a pinch of turmeric powder from your kitchen and mix it with a little water to make a paste. Now, spread this paste thinly on a piece of paper and let it dry. Then, put a drop of lemon juice (an acid) on one part of the paper, and a drop of soap solution (a base) on another part — and see what happens! Socho zara — why do you think the color changed? And can you find any other natural things around your home that could act as indicators?

See interactive experiment in app →