Law of multiple proportions (Dalton) — Hinglish notes

1.1.10 · Chemistry › Matter, Measurement & the Mole

YEH LAW HAI KYA?

Isko iske sibling law se compare karo taaki confuse na ho:

Law	Kis pe laagu hota hai	Kya kehta hai
Definite/Constant Proportions	EK compound	Mass se composition hamesha same rehti hai
Multiple Proportions	Ek hi do elements ke DO YA ZYADA compounds	Fixed-mass-of-A → B ki masses ek small integer ratio mein hoti hain

YEH SACH KYU HAI? (Atoms se derivation — first principles)

Dalton ko grams-per-atom ka koi andaza nahi tha, lekin hum exactly dekh sakte hain ki yeh kyu kaam karta hai.

Step 1 — atoms mass ki indivisible units hain. Maano A ke ek atom ki mass $m_{A}$ hai aur B ke ek atom ki mass $m_{B}$ hai. Yeh nature ke fixed constants hain.

Step 2 — compounds mein atom counts integer hote hain. (Kyu? Kyunki aap ek molecule mein aadha atom nahi daal sakte.) Compound 1 ka formula $A_{p_{1}} B_{q_{1}}$ hai; Compound 2 ka $A_{p_{2}} B_{q_{2}}$ hai, jahan $p, q$ integers hain.

Step 3 — A ki fixed mass ke liye B ki mass likhte hain. Compound $i$ mein, A ki mass $= p_{i} m_{A}$ hai, B ki mass $= q_{i} m_{B}$ hai. Toh

$(\frac{mass B}{mass A})_{i} = \frac{q _{i} m _{B}}{p _{i} m _{A}}$

Step 4 — A ki mass fix karo (dono compounds ke beech ratio lo). (Kyu divide karte hain? "A ki fixed mass" ka matlab hai hum A ko normalise kar dete hain.)

$\frac{( mass B per unit A ) _{1}}{( mass B per unit A ) _{2}} = \frac{q _{1} / p _{1}}{q _{2} / p _{2}} = \frac{q _{1} p _{2}}{q _{2} p _{1}}$

Yahan har letter ek integer hai → poori cheez integers ka ratio hai → ek simple whole-number ratio.

Figure — Law of multiple proportions (Dalton)

Worked Examples

Common Mistakes (Steel-man + Fix)

Recall Feynman: ek 12-saal ke bachche ko samjhao (chupaaya hua hai — pehle khud try karo!)

LEGO socho. Carbon ek laal brick hai, oxygen ek neeli brick hai. Tum "1 laal + 1 neeli" aur "1 laal + 2 neeli" bana sakte ho. Kyunki tum sirf poori neeli bricks daal sakte ho (kabhi aadhi brick nahi), doosri toy mein neeli ka amount exactly pehli se do guna hai — ek clean 1-to-2. Kyunki atoms chhote toot-na-sakne wale bricks hain, oxygen ki masses saaf whole-number ratios mein aati hain. Yeh saafai isbaat hai ki matter chhote ginne-waale tukdon se bana hai.

Flashcards

Law of multiple proportions batao

Jab do elements ek se zyada compound banate hain, toh ek element ki masses jo doosre element ki fixed mass ke saath combine hoti hain, woh small whole numbers ke ratio mein hoti hain.

Yeh kisne aur kab propose kiya

John Dalton, 1803.

Mass ratio banane se PEHLE kya karna chahiye

Dono compounds mein ek element ki mass fix (scaling se barabar) karni chahiye.

CO vs CO₂ mein, fixed 12 g C ke liye oxygen ratio

16 g : 32 g = 1 : 2.

SO₂ vs SO₃ mein, fixed 32 g S ke liye oxygen ratio

32 g : 48 g = 2 : 3.

Ratio integer kyu hota hai, deep reason

Compounds mein whole numbers of atoms hote hain, aur har atom ki mass fixed hoti hai, isliye mass ratios integer atom-counts ke ratios mein reduce ho jaate hain.

Law of definite proportions se fark

Definite = ek compound ki constant composition; multiple = same elements ke do+ compounds ko compare karna.

Kya raw masses non-integers ho sakti hain?

Haan; sirf reduced ratio (ek element fix karne ke baad) small whole numbers mein hona chahiye.

Connections

Law of definite (constant) proportions — iska sibling; ek compound vs kai compounds.
Law of conservation of mass (Lavoisier) — doosra pillar jis par Dalton ne banaya.
Dalton's atomic theory — yeh law iska sabse strong evidence hai.
Mole concept and Avogadro number — mass ratios ko atom counts mein convert karta hai.
Empirical and molecular formula — practice mein integer atom ratios.
Law of reciprocal proportions (Richter) — combining-mass ka chautha law.

YEH LAW HAI KYA?

YEH SACH KYU HAI? (Atoms se derivation — first principles)

Worked Examples

Common Mistakes (Steel-man + Fix)

Flashcards

Connections

Concept Map