Law of conservation of mass (Lavoisier) — proof, examples

1.1.8 · Chemistry › Matter, Measurement & the Mole

LAW kya hai?

Woh keyword jo sab kuch carry karta hai: closed/isolated. Agar gas bahar nikal jaaye ya hawa andar aa jaaye, toh balance container ke liye toot jaata hai, universe ke liye nahi.

YEH SACH KYUN HAI? (First principles se derivation)

Hum ise sirf assert karne ki bajaye atomic theory se derive karte hain.

Yahi wajah hai ki hum chemical equations balance karte hain: balancing $N_{i}^{before} = N_{i}^{after}$ enforce karta hai, jo hai hi atomic level par conservation of mass.

LAVOISIER NE ISSE KAISE PROVE KIYA? (Experiment)

Figure — Law of conservation of mass (Lavoisier) — proof, examples

Common mistakes (Steel-manned)

Recall Feynman: ek 12-saal ke bache ko samjhao

Socho tum exactly 100 LEGO bricks se ek toy castle banate ho, phir todke ek spaceship banate ho. Tumhare paas abhi bhi exactly 100 bricks hain — tumne koi nahi khoye, bas rearrange kiye. Atoms bhi aise hi kaam karte hain. Jab lakdi jalti hai aur "disappear" lagti hai, atoms actually invisible smoke aur gas ban ke udh jaate hain. Agar tum us saari gas ko ek sealed box mein trap karo aur weigh karo, toh box exactly pehle jitna hi weighs karega. Kuch bhi kabhi really lost nahi hota — woh bas kapde badal leta hai.

Active-recall flashcards

#flashcards/chemistry

Law of Conservation of Mass batao

Ek closed system mein, reactants ki total mass = products ki total mass; mass na create hoti hai na destroy hoti hai ek chemical reaction mein.

Kisne propose kiya aur kab

Antoine Lavoisier, 1789.

Law observe karne ke liye system closed kyun hona chahiye

Taaki koi gas andar ya bahar na ja sake; warna container ki mass badlti hai chahe universe ki mass conserved ho.

First principles se, mass conserved kyun hoti hai

Atoms sirf rearrange hote hain, create/destroy nahi; har element ka atom count aur atomic mass unchanged rehta hai, isliye total mass (

\sum N_{i} m_{i}

) unchanged rehti hai.

Equation balance karna law se kaise related hai

Balancing dono sides par equal atom counts enforce karta hai, jo atomic level par conservation of mass hai.

10 g CaCO₃ khule mein garam karne par 5.6 g solid bachta hai — 4.4 g kahaan gaya

CO₂ gas ban ke nikal gaya; total (5.6 + 4.4) = 10 g abhi bhi conserved hai.

2 g H₂ + 16 g O₂ → paani ki mass

18 g.

Yeh law kab fail lagti hai

Nuclear reactions mein, jahaan mass energy mein convert hoti hai (

E = m c^{2}

), ek measurable mass defect deta hai.

Lavoisier ne kya garam kiya, aur kis apparatus mein

Mercury ko ek sealed retort mein; HgO bana jabki sealed air ne oxygen kho di, total mass constant rahi.

Connections

Dalton's Atomic Theory — woh postulate deta hai (atoms indestructible hain) jo is law ko prove karta hai.
Balancing Chemical Equations — conservation of mass ka practical enforcement.
Law of Definite Proportions — Lavoisier/Proust ke mass laws mein se agla.
Stoichiometry and the Mole — reactant/product amounts relate karne ke liye mass conservation use karta hai.
Mass–Energy Equivalence (E=mc²) — jahaan classical law toot jaati hai.