🌈 Exploring Substances – Acidic, Basic, and Neutral (Summary with NCERT Solutions 2025)
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| Exploring Substances Acidic, Basic and Neutral (AI Generated Image) |
On National Science Day, siblings Ashwin and Keerthi visited a science fair at their school. At the entrance, they received white sheets that magically displayed the words “Welcome to the Wonderful World of Science” when sprayed with a liquid. Curious to know how this happened, they explored a stall named “The Colourful World of Substances.” This marked the beginning of their journey to learn about acids, bases, and neutral substances.
🧪 Testing Substances with Litmus Paper
Their first experiment involved litmus paper, a natural indicator obtained from lichens. It comes in two colors — blue and red.
- Substances that turn blue litmus red are acidic.
- Substances that turn red litmus blue are basic.
- Substances that cause no color change are neutral.
They tested items like lemon juice, vinegar, amla juice, soap solution, baking soda, lime water, and sugar solution.
After testing, they classified substances into three groups:
- Basic (Group B): Soap solution, baking soda solution, lime water, washing powder solution — all turned red litmus blue.
- Neutral (Group C): Tap water, sugar solution, salt solution — no change in color.
🍋 Taste and Touch of Substances
Ashwin and Keerthi learned that:
- Acids usually have a sour taste (like lemon, tamarind, and vinegar).
- Bases feel soapy or slippery (like soap or baking soda solution) and taste bitter.
However, tasting unknown substances can be dangerous, so it should never be done without guidance.
🌹 Natural Indicators from Flowers
They discovered that many flowers and plants can also act as indicators.
Using red rose petals, they prepared a rose extract:
- When lemon juice was added, it turned red, showing acidity.
- When soap solution was added, it turned green, showing basic nature.
Thus, red rose extract is also an acid-base indicator. Other plants like beetroot, purple cabbage, turmeric, hibiscus, and jamun can be used similarly.
A fun fact they learned: the Hydrangea flower changes color depending on the soil — blue in acidic soil and pink/red in basic soil.
🌿 Turmeric as an Indicator
Turmeric (haldi) is another natural indicator.
They prepared turmeric paper strips and tested various
substances:
- The yellow turmeric paper turned red or brown in basic solutions (like soap).
- It showed no change with acids or neutral substances.
Hence, turmeric helps identify bases but not acids or neutrals.
This also explains why soap stains on turmeric-stained
clothes turn red — because soap is basic.
👃 Olfactory Indicators (Smell-Based)
Some substances change smell in acidic or basic environments.
Example: Onion juice or cloth strips soaked in onion lose
their smell in basic solutions (like baking soda) but retain it in acidic ones
(like tamarind water).
Such substances are called olfactory indicators.
🔥 When Acids and Bases Mix — Neutralization
Next, they learned what happens when an acid and a base mix.
In an experiment, they mixed lemon juice (acid) with lime
water (base) and observed that the solution eventually became neutral — neither
acidic nor basic.
This process is called Neutralisation Reaction:
Acid + Base → Salt + Water + Heat
This reaction releases heat and forms salt and water.
🌍 Neutralisation in Daily Life
1. Ant Bite: Ants inject formic acid into the skin. Applying baking soda (a base) neutralizes the acid and relieves pain.
2. Soil Treatment:
- If soil is too acidic, add lime (base).
- If soil is too basic, add organic matter like compost, which releases acids.
3. Factory Waste: Before releasing waste into lakes, factories neutralize acidic waste using basic substances to protect aquatic life.
These real-life examples show how neutralization helps
balance the environment and health.
🧠
Key Takeaways (“In a Nutshell”)
- Indicators like litmus, red rose, turmeric, and lichen extracts help identify their nature.
- Acids turn blue litmus red, while bases turn red litmus blue.
- Rose extract becomes red in acids and green in bases.
- Turmeric turns red in bases but remains yellow in acids or neutrals.
- Mixing acids and bases causes neutralization, forming salt, water, and heat.
- Neutralization is useful in ant bite relief, soil treatment, and pollution control.
~~The END~~
Chapter 2 Exploring Substances Acidic, Basic and neutral
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