"Dilute" aur "Concentrated" Kaafi Nahi 🤔
Pichle lesson mein humne kaha ki jis solution mein solute kam ho wo "dilute", zyada ho wo "concentrated". Lekin ye words vague (dhundhle) hain. Ek doctor ko ye kaafi nahi ki dawa "thodi gaadhi" hai - use exact maatra chahiye. Isliye scientists solution ki Concentration ko numbers mein naapte hain.
📌 Concentration = ek diye gaye maatra ke solution (ya solvent) mein kitna solute
ghula hai. Ise aksar percentage (%) mein batate hain. Yaad rakho:
Mass of solution = Mass of solute + Mass of solvent
Class 9 mein hum concentration ko teen tareekon (percentage) se naapte hain. Chaliye ek-ek karke, formula aur solved examples ke saath samjhein.
1️⃣ Mass by Mass Percentage (w/w %)
Jab solute aur solvent dono ki maatra mass (grams) mein di ho, toh:
📐 Mass % = (Mass of solute ÷ Mass of solution) × 100
jahan Mass of solution = Mass of solute + Mass of solvent
✔ Solved Example 1:
40 g paani mein 10 g cheeni ghulaayi gayi. Solution ki mass % concentration nikalo.
Step 1 - Diya hua: Solute (cheeni) = 10 g, Solvent (paani) = 40 g
Step 2 - Mass of solution: = 10 + 40 = 50 g
Step 3 - Formula lagao: Mass % = (10 ÷ 50) × 100 = 20%
Matlab is solution ka 20% hissa cheeni hai.
✔ Solved Example 2:
Ek solution mein 15 g namak, 85 g paani mein ghula hai. Mass % kya hoga?
Solution: Mass of solution = 15 + 85 = 100 g.
Mass % = (15 ÷ 100) × 100 = 15%.
Tip: Jab solute + solvent = 100 g ho, toh solute ki grams hi seedha percentage ban jaati hai!
✔ Solved Example 3 (thoda ulta - reverse):
Ek 25% (mass) namak solution ke 200 g mein kitna namak hai?
Solution: 25% ka matlab har 100 g solution mein 25 g namak.
200 g solution mein namak = (25 ÷ 100) × 200 = 50 g namak (aur 150 g paani).
2️⃣ Mass by Volume Percentage (w/v %)
Jab solute ki maatra mass (g) mein aur solution ki maatra volume (mL) mein ho, toh:
📐 Mass by Volume % = (Mass of solute in g ÷ Volume of solution in mL) × 100
✔ Solved Example 4:
2 g namak ko paani mein ghulaakar total 50 mL solution banaya gaya. Mass by volume % nikalo.
Solution: = (2 ÷ 50) × 100 = 4% (w/v).
✔ Solved Example 5 (real-life - IV saline):
Hospital ki "normal saline" (IV drip) mein 0.9 g namak, 100 mL solution mein hota hai. Iski concentration kya hai?
Solution: = (0.9 ÷ 100) × 100 = 0.9% (w/v). Isi liye ise "0.9% saline" kaha jaata hai - ye hamare body ke fluids se match karti hai!
3️⃣ Volume by Volume Percentage (v/v %)
Jab solute aur solution dono liquid (volume/mL) mein hon (jaise do liquids ka mixture), toh:
📐 Volume % = (Volume of solute ÷ Volume of solution) × 100
✔ Solved Example 6:
20 mL alcohol ko paani mein milaakar 200 mL solution banaya gaya. Volume % nikalo.
Solution: = (20 ÷ 200) × 100 = 10% (v/v).
Aapne suna hoga hand sanitizer "70% alcohol" wala hota hai - ye volume by volume % hai! Matlab har 100 mL sanitizer mein 70 mL alcohol. Yahi 70% concentration germs maarne ke liye sabse achhi maani jaati hai.
🧾 Kaunsa Formula Kab? - Ek Nazar Mein
| Solute ki unit | Solution/Solvent ki unit | Formula |
|---|---|---|
| Mass (g) | Mass (g) | Mass by Mass % (w/w) |
| Mass (g) | Volume (mL) | Mass by Volume % (w/v) |
| Volume (mL) | Volume (mL) | Volume by Volume % (v/v) |
📌 Golden rule: Denominator (neeche) mein hamesha solution ki maatra aati hai (solute + solvent), sirf solvent ki nahi. Aur × 100 karna kabhi mat bhoolna!
Solute aur solvent ki maatra badlo aur teeno percentages live nikalte dekho - steps ke saath.
Open Calculator →✏️ Khud Try Karo (Practice Problems)
Q. Khud solve karo (answers neeche):
- 30 g cheeni ko 120 g paani mein ghulaaya. Mass % kya hai?
- 5 g glucose se 250 mL solution banaya. Mass by volume % kya hai?
- Ek 20% (mass) solution ke 300 g mein kitna solute hai?
Answers: 1) (30 ÷ 150) × 100 = 20% 2) (5 ÷ 250) × 100 = 2% 3) (20 ÷ 100) × 300 = 60 g
🧠 Chalo Test Karein! (Quick Quiz)
Apne aap ko check karo 👇
📌 Aage Kya? (Coming Next)
Ab tak humne true solutions dekhe. Lekin doodh, dhundh (fog), aur mitti-paani jaise mixtures thode alag hote hain. Agle lesson mein: Suspensions, Colloids aur Tyndall effect.