Preparation, properties, uses of dihydrogen — Hinglish notes

3.1.3 · Chemistry › Hydrogen and s-Block

Overview

Dihydrogen (H₂) universe mein sabse zyada paaya jaane wala element hai aur ek bahut zaroori industrial chemical bhi hai. Iske preparation methods, physical aur chemical properties, aur applications ko samajhna industrial chemistry aur energy systems ke liye fundamental hai.

Preparation of Dihydrogen

Laboratory Preparation

Method 1: Metals ka Acids ke Saath Reaction

Principle: Active metals (Zn, Fe, Al) dilute acids se hydrogen ko displace karte hain.

First Principles se Derivation:

Metals ki ionization energies low hoti hain → aasaani se cations banate hain
Acids solution mein H⁺ ions provide karte hain
Jab metal electrons khota hai: M → M^n+^ + ne⁻
H⁺ electrons leta hai: 2H⁺ + 2e⁻ → H₂
Net reaction dono half-reactions ko combine karta hai

YEH KYU kaam karta hai: H⁺/H₂ ka reduction potential (-0.00 V) active metals se zyada hai (Zn²⁺/Zn = -0.76 V), isliye reaction spontaneous hoti hai.

$Zn(s) + 2HCl(aq) \to ZnCl_{2} (aq) + H_{2} (g)$

$Zn(s) + H_{2} SO_{4} (aq) \to ZnSO_{4} (aq) + H_{2} (g)$

KAISE perform karein:

Granulated zinc ko dilute H₂SO₄ ya HCl mein ek conical flask mein daalo
Gas ko water ke upar collect karo (inverted tube mein paani ko displace karta hai)
Granulated kyun? → Zyada surface area = tez reaction
Dilute acid kyun? → Concentrated H₂SO₄ oxidizing hota hai aur H₂ ki jagah SO₂ produce karta hai

Solution:

Step 1: Balanced equation likho $Zn + 2HCl \to ZnCl_{2} + H_{2}$ Kyun? Stoichiometry mole ratio determine karta hai
Step 2: Zn ke moles calculate karo $n_{Zn} = \frac{13 g}{65 g/mol} = 0.2 mol$ Kyun? Mass ko moles mein convert karo molar mass use karke
Step 3: Stoichiometry use karo (1:1 mole ratio) $n_{H_{2}} = 0.2 mol$ Kyun? Ek mole Zn ek mole H₂ produce karta hai
Step 4: STP par volume calculate karo $V = n \times 22.4 L/mol = 0.2 \times 22.4 = 4.48 L$ Kyun? STP par, 1 mole gas = 22.4 L

Answer: 4.48 L of H₂

Method 2: Alkali Metals/Hydrides ka Water ke Saath Reaction

$2 Na (s) + 2 H_{2} O (l) \to 2 NaOH (a q) + H_{2} (g)$

$CaH_{2} (s) + 2 H_{2} O(l) \to Ca(OH)_{2} (aq) + 2 H_{2} (g)$

CaH₂ KYU kaam karta hai: Metal hydrides mein, H H⁻ (hydride ion) ke roop mein exist karta hai. Paani H⁺ provide karta hai. Reaction acid-base hai: $H^{-} (aq) + H^{+} (aq) \to H_{2} (g)$

Yeh method bahut pure H₂ produce karta hai kyunki koi acidic impurities present nahi hoti.

Industrial Preparation

Method 1: Hydrocarbons ki Steam Reforming (Bosch Process)

Sabse common industrial method (~95% H₂ production yahi se hota hai)

Step 1: 1000-1200 K par Ni catalyst ke saath steam reforming $CH_{4} (g) + H_{2} O(g) Ni, 1000K CO(g) + 3 H_{2} (g)$ $Δ H = + 206 kJ/mol (endothermic)$

Ni catalyst KYU? C-H bond breaking ke liye activation energy kam karta hai. High temperature isliye chahiye kyunki reaction endothermic hai.

Step 2: 673 K par Fe/Cr catalyst ke saath water-gas shift reaction $C O (g) + H_{2} O (g) Fe, 673K C O_{2} (g) + H_{2} (g)$ $Δ H = - 41 kJ/mol (exothermic)$

YEH step KYU? CO (poisonous) ko CO₂ mein convert karta hai aur additional H₂ produce karta hai. Kam temperature exothermic forward reaction ko favor karta hai (Le Chatelier).

Net Reaction ki Derivation: Dono equations add karo: $C H_{4} + H_{2} O \to C O + 3 H_{2}$ $CO + H_{2} O \to CO_{2} + H_{2}$ $CH_{4} + 2 H_{2} O \to CO_{2} + 4 H_{2}$

Overall energy: (+206) + (-41) = +165 kJ/mol → Phir bhi endothermic hai, external heat chahiye

Solution:

Step 1: CH₄ ke theoretical moles calculate karo $n_{CH_{4}} = \frac{16000 g}{16 g/mol} = 10000 mol$ Kyun? Stoichiometry ke liye moles mein convert karo
Step 2: Stoichiometry use karo (1:4 ratio) $n_{H_{2}} = 1000 \times 4 = 40000 mol (theoretical)$ Kyun? 1 mol CH₄ → 4 mol H₂
Step 3: Theoretical mass calculate karo $m_{H_{2}} = 4000 \times 2 = 80000 g = 80 kg$ Kyun? H₂ ki molar mass = 2 g/mol
Step 4: Efficiency apply karo $Actual = 80 \times 0.80 = 64 kg$ Kyun? Sirf 80% successfully convert hota hai

Answer: 64 kg H₂ per day

Method 2: Water ki Electrolysis

$2H_{2} O(l) electricity 2H_{2} (g) + O_{2} (g)$

Electrochemical principles se Derivation:

Cathode par (reduction): $2H_{2} O + 2 e^{-} \to H_{2} + 2 OH^{-}$ $E ° = - 0.83 V$

Anode par (oxidation): $\ce 2 O H^{-} - > \frac{1}{2} O 2 + H 2 O + 2 e^{-}$ $E ° = + 0.40 V$

Minimum voltage required: $E_{cell} = E_{cathode} - E_{anode} = - 0.83 - 0.40 = - 1.23 V$

NEGATIVE KYU? Non-spontaneous process hai, external energy input chahiye.

Practical voltage: 1.8-2.0 V (overpotential aur resistance account karta hai)

Advantages: Bahut pure H2 produce karta hai (>99.9%), electronics aur fuel cells ke liye useful Disadvantages: Energy-intensive (30-50 kWh per kg H2), sirf wahan economic hai jahan bijli sasti ho

[!formula] Electrolysis ke liye Faraday's Law Produce hone waale substance ki amount, pass hone wale charge ke proportional hoti hai: $n = \frac{Q}{z F} = \frac{I t}{z F}$

Derivation:

Q = total charge (coulombs) = I × t
z = number of electrons per molecule (H₂ ke liye, z = 2)
F = Faraday constant = 96485 C/mol
KYU? Har transferred electron 1/z molecule deposit karta hai

$Mass of \ce H 2 = n \times M = \frac{I t \times M}{z F}$

H2 ke liye: $m = \frac{I t \times 2}{96485} = \frac{I t}{96485} grams$

[!example] Worked Example 3: Electrolysis Calculation Problem: Paani mein 5 A ki current 2 ghante tak pass hoti hai. Calculate karo (a) produce hone wala H2 ka mass, (b) STP par volume.

Solution (a):

Step 1: Charge calculate karo $Q = I \times t = 5 \times (2 \times 3600) = 36000 C$ Kyun? Current × time = charge; ghante ko seconds mein convert karo

Step 2: Faraday's law se moles calculate karo $n_{\ce H 2} = \frac{Q}{z F} = \frac{36000}{2 \times 96485} = 0.1865 mol$ Kyun? Har H₂ molecule ke liye 2 electrons chahiye
Step 3: Mass calculate karo $m = 0.1865 \times 2 = 0.373 g$ Kyun? Moles ko molar mass se multiply karo

Solution (b): $V = n \times 22.4 = 0.1865 \times 22.4 = 4.18 L at STP$ Kyun? STP par 1 mole gas = 22.4 L

Answer: (a) 0.373 g, (b) 4.18 L

Method 3: Coal Gasification

$\ce C (s) + H 2 O (g) - > [1270K] C O (g) + H 2 (g)$

Iske baad water-gas shift reaction hoti hai. Wahan use hota hai jahan coal abundant aur sasta ho.

Properties of Dihydrogen

Physical Properties

Quantitative Properties:

Molecular mass: 2.016 g/mol (sabse halka molecule)
Density: 0.089 g/L at STP (compare: air = 1.29 g/L)
Melting point: 14 K (-259°C)
Boiling point: 20K (-253°C)
Bond dissociation energy: 436 kJ/mol (single bond ke liye bahut strong)

Low boiling point KYU?

Molecules ke beech sirf London dispersion forces hoti hain
Chhota molecular size → weak intermolecular forces
Derivation: Boiling point ∝ intermolecular force strength ∝ molecular size/polarizability
H₂ ki polarizability minimal hai → sabhi molecules mein sabse kam b.p.

Low density KYU? STP par: $ρ = \frac{M}{V _{m}} = \frac{2.016}{22.4} = 0.090$ g/L

Sabse halka molecule → sabse kam density

Diffusion: Tezi se diffuse karta hai (rate ∝ 1/√M Graham's law se) $\frac{r _{\ce H 2}}{r _{\ce O 2}} = \frac{M _{\ce O 2}}{M _{\ce H 2}} = \frac{32}{2} = 4$

H₂, O₂ se 4 guna tez diffuse karta hai

Solubility: Paani mein kam ghulta hai (0.002 g/100 mL at 20°C) KYU? Nonpolar molecule hai, paani ke saath H-bonds nahi bana sakta

Chemical Properties

[!intuition] Reactivity Pattern H₂ room temperature par relatively unreactive hota hai, halanki thermodynamically react karna favorable ho. KYU? High bond dissociation energy (436 kJ/mol) ek bada activation barrier create karta hai.

Elevated temperatures ya catalysts ke saath: H₂ bahut zyada reactive ho jaata hai.

1. Air/Oxygen mein Combustion

Sabse zyada exothermic reaction: $\ce 2 H 2 (g) + O 2 (g) - > 2 H 2 O (l)$ $Δ H = - 286 kJ/mol$ Enthalpy ki derivation:
$&\text{Breaking 2 H-H bonds: } 2(+436) = +872 \text{ kJ}\\ &\text{Breaking 1 O=O bond: } +498 \text{ kJ}\\ &\text{Forming 4 O-H bonds: } 4(-464) = -1856 \text{ kJ}\\ &\text{Net: } +872 + 498 - 1856 = -486 \text{ kJ/2 mol H}_2 = -243 \text{ kJ/mol H}_2 \end{aligned}$$ (Actual $\Delta H = -286 \text{ kJ/mol}$ mein water vapor ka condensation bhi shamil hai) Explosive range: Air mein 4-75% H₂ Explosive KYU hota hai? Highly exothermic + rapid chain reaction propagation Common Error: Combustion aur Explosion mein Confusion Galat: "H₂ combustion hamesha explode karti hai." Yeh sahi kyun lagta hai: H₂ + O₂ → lab mein loud pop Haqeeqat: $$\begin{aligned} &\text{Combustion: Controlled, deflagration (subsonic flame propagation)}\\ &\text{Explosion: Uncontrolled, detonation (supersonic shock wave)}\\ &\text{Requires 4-75\% H}_2 \text{ in specific ratio} \end{aligned}$$ Fix: Pure H₂ jo proper mixing ke saath air mein jalti hai woh controlled combustion hai 2. Halogens ke Saath Reaction Reactivity order: F₂ > Cl₂ > Br₂ > I₂ Fluorine ke saath (explosive, andheron mein bhi, $-200°$C par): $$\ce{H2 + F2 -> 2HF}$$$

$Δ H = - 271 kJ/mol$

Itna reactive KYU? F₂ ki X-X bond sabse kamzor hoti hai (158 kJ/mol) kyunki chhote F atom mein electron-electron repulsion hoti hai.

Chlorine ke saath (sunlight ya heating chahiye): $\ce H 2 + C l 2 - > [hν or Δ] 2 H C l$ $Δ H = - 185 kJ/mol$

Mechanism (chain reaction):

Initiation: $\ce C l 2 - > [hν] 2 C l \cdot$
Propagation: $\ce C l \cdot + H 2 - > H C l + H \cdot$
Propagation: $\ce H \cdot + C l 2 - > H C l + C l \cdot$
Termination: $\ce C l \cdot + C l \cdot - > C l 2$

Photochemical KYU? Light Cl-Cl bond (243 kJ/mol) todne ki energy provide karti hai, free radicals initiate karta hai.

3. Metal Oxides ka Reduction

H₂ reducing agent ki tarah kaam karta hai, metal oxides se oxygen hataata hai:

$\ce C u O (s) + H 2 (g) - > [Δ] C u (s) + H 2 O (g)$

$\ce F e 2 O 3 (s) + 3 H 2 (g) - > [Δ] 2 F e (s) + 3 H 2 O (g)$

Feasibility ki Derivation:

H₂ ki oxygen ke liye strong affinity hai (stable H-O bonds banata hai)
ΔG < 0 jab: ΔH(H₂O ka formation) < ΔH(metal oxide ka formation)
Kaam karta hai: Cu, Pb, Fe, Zn oxides ke liye
Kaam NAHI karta: Alkali metal oxides, CaO, MgO, Al₂O₃ ke liye (bahut zyada stable hain)

Temperature KYU chahiye? M-O bonds todne ke liye activation energy overcome karta hai.

Solution:

Step 1: Balanced equation likho $\ce A l 2 O 3 + 3 H 2 - > 2 A l + 3 H 2 O$ Kyun? Energy calculation ke liye stoichiometry chahiye
Step 2: Reaction ke liye ΔH° calculate karo $Δ H ° = [3 (- 286)] - [- 1676] = - 858 + 1676 = + 818 kJ$ Kyun? ΔH = Σ(products) - Σ(reactants)
Step 3: Sign interpret karo Highly endothermic → Non-spontaneous Kyun? Al₂O₃, H₂O se zyada stable hai

Answer: Nahi, H₂, Al₂O₃ ko reduce nahi kar sakta (Al₂O₃ bahut zyada stable hai)

4. Metals ke Saath Reaction (Hydride Formation)

High temperature par reactive metals ke saath: $\ce 2 N a (s) + H 2 (g) - > [Δ] 2 N a H (s)$ (ionic hydride) $Ca(s) + H_{2} (g) Δ CaH_{2} (s)$ (ionic hydride) $Pd(s) + xH_{2} (g) \to PdH_{x}$ (interstitial hydride)

Bonding ke basis par classification:

Ionic hydrides: s-block metals, H⁻ ion contain karte hain
Covalent hydrides: p-block elements (H₂O, CH₄, NH₃)
Metallic/interstitial hydrides: d-block metals, H atoms metal lattice mein hote hain

5. Unsaturated Compounds ka Hydrogenation

C=C double bonds ke across catalyst ke saath addition: $C_{2} H_{4} (g) + H_{2} (g) Ni/Pt/Pd C_{2} H_{6} (g)$

$C_{6} H_{5} C H = C H_{2} + H_{2} N i C_{6} H_{5} C H_{2} C H_{3}$

Vegetable oil hardening: $Liquid oil + H_{2} Ni, 473K Solid fat$

Catalyst KYU chahiye?

H₂ bond strong hai (436 kJ/mol)
Catalyst H₂ ko adsorb karta hai → H-H bond kamzor karta hai
Metal surface reactants ko paas laata hai
Activation energy ~250 kJ/mol se ~50 kJ/mol tak kam karta hai

Uses of Dihydrogen

1. Ammonia Synthesis (Haber Process)

Sabse bada use (~50% global H₂ production)

$N_{2} (g) + 3 H_{2} (g) ⇌ 2 N H_{3} (g)$ $Δ H = - 92 kJ/mol$

Conditions: 700K, 200-250 atm, Fe₃O₄/K₂O/Al₂O₃ catalyst

YEH conditions KYU?

Exothermic: Kam T products favor karta hai, lekin bahut slow hota hai
ΔV negative (4 mol → 2 mol): High P products favor karta hai
Compromise: Moderate T (itna fast kaafi hai) + High P (accha yield)

Ammonia use hoti hai: Fertilizers (80%), plastics, explosives, cleaning agents mein

2. Methanol Production

$CO(g) + 2 H_{2} (g) ZnO/Cr_{2} O_{3} 500 K, 250 atm CH_{3} OH(l)$

KYU important hai? Methanol, formaldehyde, acetic acid, aur potential fuel ka feedstock hai

3. Petroleum Refining (Hydrocracking)

Bade hydrocarbons ko chhote mein todta hai: $C_{20} H_{42} + H_{2} catalyst Δ, P C_{10} H_{22} + C_{10} H_{20} + \dots$

Hydrodesulfurization: Crude oil se sulfur remove karta hai $RSH + H_{2} \to RH + H_{2} S$

KYU zaroori hai? Cleaner fuels produce karta hai, SO₂ emissions kam karta hai

4. Margarine aur Vanaspati Ghee Production

Unsaturated fats ka hydrogenation: $Vegetable oil (liquid) + H_{2} Ni 473K Vanaspati (semi-solid)$

Mechanism: C=C ko C-C mein convert karta hai, melting point badhata hai

5. Metal Extraction aur Purification

Metal oxides ka reduction: $WO_{3} + 3 H_{2} \to W + 3 H_{2} O$

Use hota hai: Tungsten, molybdenum, copper extraction ke liye

6. Rocket Fuel (Liquid Hydrogen)

Liquid H₂ + Liquid O₂ → Sabse efficient chemical rocket propellant

Specific impulse: 450s (gasoline: 250 s)

Best KYU hai?

Sabse zyada energy/mass ratio
Clean exhaust (sirf H₂O)
Calculation: $Specific impulse = \frac{Thrust}{Weight flow rate}$

Challenges: Cryogenic storage (-253°C), kam density

7. Fuel Cells (Clean Energy)

$2 H_{2} + O_{2} \to 2 H_{2} O + Electrical energy$

Efficiency: 40-60% (vs combustion engines ka 25-30%)

Advantages: Zero emissions, quiet, modular Disadvantages: H₂ storage, infrastructure, cost

8. Oxy-hydrogen Torch

$2H_{2} + O_{2} \to 2H_{2} O$

Achieve hone wala temperature: 2800-3000°C

Use hota hai: Metal cutting, welding (khaaskar underwater)

9. Weather Balloons

H₂ KYU? Sabse kam density → maximum lift Aajkal ki preference: Helium (non-flammable), lekin jahan cost matter kare wahan H₂ abhi bhi use hota hai

Recall Ek 12 saal ke bachche ko samjhao

Imagine karo tumhare paas universe ki sabse halki gas hai - itni halki ki isse bhra hua balloon seedha sky mein chala jaata hai! Yahi hai hydrogen gas, yaani H₂ (do hydrogen atoms haath pakde hue).

Kaise banate hain: Tum ise apni rasoi mein bana sakte ho (try mat karna!) zinc jaisi koi metal ko acid mein daalo - woh fizz karta hai aur hydrogen ke bubbles release karta hai. Factories ise TONS mein banati hain natural gas ko bahut garam steam ke saath mix karke, thoda jaise Lego blocks tod ke naye pieces hasil karna.

Kaisa hota hai? Yeh invisible hai, koi smell nahi, aur agar tum ise pakadne ki koshish karo, toh kuch feel nahi hoga. Yeh hawa se 14 guna halka hai! Lekin yeh bada interesting part hai - yeh JALANA CHAHTA hai. Ise oxygen ke saath mix karo aur aag lagao: BOOM! Woh explosion itni energy release karta hai ki rockets liquid hydrogen ko fuel ki tarah use karke space mein jaate hain.

Kism kaam aata hai? Hum hydrogen use karte hain fertilizer banane ke liye (taaki plants acche se ugein), liquid vegetable oil ko solid butter-jaisi cheez (vanaspati) mein convert karne ke liye, petrol saaf karne ke liye taaki woh pollute na kare, aur yahan tak ki special "fuel cell" cars power karne ke liye jo sirf paani "exhale" karti hain!

Mushkil baat? Hydrogen bahut reactive hai aur aasaani se explode kar sakta hai, plus ise store karna mushkil hai kyunki molecules itne tiny hain ki almost har cheez se leak karte hain. Lekin scientists ise isliye love karte hain kyunki ise jalana bahut clean hai - sirf paani banta hai, koi smoke ya pollution nahi!

Preparation methods ke liye: "MASH SCoRE"

Metal + Acid → Small-scale Hydrogen
Steam reforming → Commercial Really Effective

Properties ke liye: "Light Harry Burns Everything Rapidly"

Light → Sabse kam density wali gas
Harry → High diffusion rate (Graham's law)
Burns → Combustible (exothermic combustion)
Everything → Metal oxides ko reduce karta hai
Rapidly → High temperature par reactive

Halogens ke saath reactivity ke liye: "Flowers Can't Bloom In Dark" F₂ (Flowers) → cold/dark mein bhi explosive Cl₂ (Can't) → light chahiye (photochemical) Br₂ (Bloom) → heat + light chahiye I₂ (In Dark) → reversible, bahut slow

Uses ke liye: "AMP-MR FuelR"

Ammonia synthesis
Methanol production
Petroleum refining (hydrocracking)
Margarine production
Reduction of metal oxides
Fuel cells
Rocket fuel

Connections

Hydrogen - Introduction and Isotopes - H₂ molecular structure samajhne ki foundation
Water Gas Shift Reaction - Industrial CO removal process
Haber Process - Ammonia synthesis ke liye major H₂ consumer
Hydrogenation Reactions - Multiple bonds ke across H₂ ka addition
Electrolysis and Faraday's Laws - H₂ production ke quantitative aspects
Fuel Cells and Hydrogen Economy - Future energy applications
Redox Reactions - H₂ reducing agent ki tarah
Hydrides - Ionic, Covalent, Metallic - Alag elements ke saath H₂ ki reactions
Thermodynamics of Chemical Reactions - H₂ reactions ki spontaneity
Graham's Law of Diffusion - H₂ ki rapid diffusion explain karta hai

#flashcards/chemistry

Dihydrogen produce karne ka sabse common industrial method kya hai aur uske do main steps kya hain? :: Steam reforming of hydrocarbons (Bosch Process). Step 1: CH₄ + H₂O → CO + 3H₂ (1000K, Ni catalyst). Step 2: CO + H₂O → CO₂ + H₂ (water-gas shift, 673K, Fe catalyst). Net: CH₄ + 2H₂O → CO₂ + 4H₂

Laboratory mein H₂ prepare karne ke liye concentrated H₂SO₄ KYU use nahi karte?

Concentrated H₂SO₄ ek strong oxidizing agent hai jo H₂ ko waapas paani mein oxidize kar deta hai aur H₂ ki jagah SO₂ produce karta hai: Zn + 2H₂SO₄(conc) → ZnSO₄ + SO₂ + 2H₂O. Sirf dilute acids H₂ gas produce karti hain.

Zinc aur dilute HCl se H₂ ki laboratory preparation ki reaction likho.

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g). Active metal dilute acid se hydrogen ko displace karta hai.

Water ki electrolysis ke liye minimum theoretical voltage kitna chahiye aur kyun?

1.23 V. Electrode potentials se calculate hota hai: E_cell = E_cathode - E_anode = (-0.83) - (+0.40) = -1.23 V. Negative value non-spontaneous process indicate karta hai jisme external energy chahiye.

Faraday's law use karke electrolysis mein produce hone wale H₂ ke mass ka formula derive karo.

n = Q/(zF) = It/(zF) se shuru karke, jahan z = 2 H₂ ke liye. Mass = n × M = (It × M)/(zF) = (It × 2)/(2 × 96485) = It/96485 grams. Current amperes mein, time seconds mein.

H₂ ki bond dissociation energy kya hai aur yeh significant kyun hai?

436 kJ/mol. Single bond ke liye bahut high hai, ek bada activation barrier create karta hai. Isse H₂ room temperature par relatively unreactive hoti hai halanki thermodynamically react karna favorable ho. Ise overcome karne ke liye heat ya catalyst chahiye.

H₂ ka boiling point itna low (20 K) KYU hota hai?

H₂ molecules sirf weak London dispersion forces experience karte hain (koi dipole nahi). Chhota molecular size → minimal polarizability → bahut weak intermolecular attractions. Boiling point intermolecular force strength ke proportional hota hai, isliye H₂ ka sabhi molecules mein sabse kam b.p. hai.

Graham's law ke according H₂, O₂ se kitna tez diffuse karta hai?

4 guna tez. Graham's law se: r_H₂/r_O₂ = √(M_O₂/M_H₂) = √(32/2) = √16 = 4. Diffusion rate molar mass ke square root ke inversely proportional hoti hai.

Oxygen mein H₂ ke combustion ka balanced equation aur ΔH likho.

2H₂(g) + O₂(g) → 2H₂O(l), ΔH = -286 kJ/mol H₂. Bahut zyada exothermic reaction hai; H₂ fuel cells aur rocket fuel ka basis banta hai. Explosive range: Air mein 4-75% H₂.

Halogens ke saath H₂ ki reactivity order kya hai aur kyun?

F₂ > Cl₂ > Br₂ > I₂. F₂ -200°C par andheron mein bhi explosively react karta hai kyunki F-F bond sabse kamzor hai (158 kJ/mol) chhote F atom mein electron-electron repulsion ki wajah se. Halogen ka size badhne aur X-X bond strength badhne ke saath reactivity kam hoti jaati hai.

Explain karo ki H₂, CuO ko reduce kar sakta hai lekin Al₂O₃ ko nahi.

Reduction ki feasibility oxides ki relative stability par depend karti hai. CuO + H₂ → Cu + H₂O ke liye, ΔH negative hai (H₂O, CuO se zyada stable hai). Al₂O₃ + 3H₂ → 2Al + 3H₂O ke liye, ΔH = +818 kJ/mol (highly endothermic) kyunki Al₂O₃, H₂O se zyada stable hai. Thermodynamically unfavorable hai.

H₂ ke metals ke saath banane wale hydrides ke teen types kya hain?

(1) Ionic hydrides: s-block metals (NaH, CaH₂), H⁻ ion contain karte hain, high temp. par bante hain. (2) Covalent hydrides: p-block elements (H₂O, CH₄, NH₃). (3) Metallic/interstitial hydrides: d-block metals, H atoms metal lattice mein hote hain.