Important compounds — NaOH, NaCl, Na₂CO₃ (Solvay), NaHCO₃; CaO, CaCO₃, gypsum, plaster of Paris

3.1.9 · Chemistry › Hydrogen and s-Block

1. Do starting rocks/brines

Figure — Important compounds — NaOH, NaCl, Na₂CO₃ (Solvay), NaHCO₃; CaO, CaCO₃, gypsum, plaster of Paris

2. Sodium hydroxide — NaOH (caustic soda)

3. Sodium carbonate — Na₂CO₃ (washing soda) Solvay process se

Formula Solvay ke steps (KAISE, ek logical chain ki tarah derived)

Step 1 — CO₂ aur CaO banao limestone ko heat karke: $C a C O_{3} Δ C a O + C O_{2}$ Step 2 — brine ko NH₃ se saturate karo, phir CO₂ se. Ammoniacal brine + CO₂ se bicarbonate ions milte hain: $N H_{3} + H_{2} O + C O_{2} \to N H_{4} H C O_{3}$ $N H_{4} H C O_{3} + N a C l \to N a H C O_{3} ↓ + N H_{4} C l$ NaHCO₃ precipitate KYU hota hai? Ye is thandi concentrated mixture mein sabse kam soluble species hai (common-ion + low solubility) → bahar nikal jaata hai, aur equilibrium ko aage kheenchta hai. Step 3 — NaHCO₃ ko heat karo (calcination): $2 N a H C O_{3} Δ N a_{2} C O_{3} + H_{2} O + C O_{2}$ Step 4 — NH₃ recover karo step 1 ke CaO se: $2 N H_{4} C l + C a (O H)_{2} \to C a C l_{2} + 2 N H_{3} + 2 H_{2} O$ Overall: $2 N a C l + C a C O_{3} \to N a_{2} C O_{3} + C a C l_{2}$ . K is tarah nahi banaya ja sakta kyunki KHCO₃ itna soluble hai ki precipitate nahi hota.

4. Sodium bicarbonate — NaHCO₃ (baking soda)

5. Calcium family — CaO, CaCO₃, gypsum, plaster of Paris

Flashcards

Electrolyte aur chlor-alkali process ki overall reaction

2 N a C l + 2 H_{2} O \to 2 N a O H + C l_{2} + H_{2}

(brine ki electrolysis)

Chlor-alkali cell mein cathode reaction

2 H_{2} O + 2 e^{-} \to H_{2} + 2 O H^{-}

(water reduce hota hai, Na⁺ nahi)

Chlor-alkali cell mein anode reaction

2 C l^{-} \to C l_{2} + 2 e^{-}

Solvay process mein NaHCO₃ precipitate KYU hota hai?

Ye thandi ammoniacal brine mein sabse kam soluble species hai, isliye crystallise ho jaata hai aur equilibrium ko aage drive karta hai.

Solvay ki overall reaction

2 N a C l + C a C O_{3} \to N a_{2} C O_{3} + C a C l_{2}

(NH₃ recycled hoke)

Solvay process mein NH₃ kaise recover hota hai?

2 N H_{4} C l + C a (O H)_{2} \to C a C l_{2} + 2 N H_{3} + 2 H_{2} O

K₂CO₃ Solvay se KYU nahi ban sakta?

KHCO₃ itna soluble hai ki precipitate nahi hota.

Sodium bicarbonate ko heating par decomposition

2 N a H C O_{3} Δ N a_{2} C O_{3} + H_{2} O + C O_{2}

Washing soda ka formula aur naam

N a_{2} C O_{3} \cdot 10 H_{2} O

(sodium carbonate decahydrate)

Na₂CO₃ solution alkaline KYU hoti hai?

C O_{3}^{2 -} + H_{2} O ⇌ H C O_{3}^{-} + O H^{-}

(weak-acid anion ka hydrolysis)

Quicklime, slaked lime ke formulas

CaO (quicklime), Ca(OH)₂ (slaked lime)

Limestone ki calcination

C a C O_{3} Δ C a O + C O_{2}

Lime mortar hawa mein KYU hard hota hai?

C a (O H)_{2} + C O_{2} \to C a C O_{3} + H_{2} O

(stone vapas banta hai)

Gypsum aur Plaster of Paris ke formulas

Gypsum

C a S O_{4} \cdot 2 H_{2} O

; PoP

C a S O_{4} \cdot \frac{1}{2} H_{2} O

Gypsum se PoP banane ka temperature

~393 K (120 °C); 473 K se upar dead-burnt anhydrous CaSO₄ milta hai jo set nahi hoga.

PoP hard KYU set hota hai?

Ye water vapas absorb karke gypsum

C a S O_{4} \cdot 2 H_{2} O

reform karta hai, ek interlocking crystal mass.

Recall Feynman: ek 12-saal ke bachche ko explain karo

Socho salty water aur white rocks nature ke free LEGO bricks hain. Salty water mein se electricity guzaaro aur bahar nikalte hain teen useful cheezein: ek strong soapy cleaner (NaOH), ek green gas (Cl₂) aur ek balloon gas (H₂). Ab white rock ko bake karo aur ye ek gas phukt hai (CO₂) aur quicklime (CaO) bachta hai — water daalo aur ye hissaata hai aur garma hota hai (slaked lime), aur time ke saath ye hawa ka CO₂ khaata hai aur wapas stone ban jaata hai — isliye purani divaaren hard hoti hain. Ek aur white rock hai, gypsum: ise dheerey bake karo aur ye apna zyaatar hidden water khota hai, ek powder ban jaata hai. Us powder ko water se milao aur ye water vapas pakad leta hai aur rock-hard ho jaata hai — tuti haddiyon ke casts ke liye perfect. Par zyada hard bake karo, aur ye sulk karta hai aur aur set karna band kar deta hai.