Question

Define all laws of chemical combination?

and define atomic weight, molecular weight, gram atomic weight , gram molecular weight and average number too.

Answer 1

Hi friend,
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(i.) LAWS OF CHEMICAL COMBINATION:-

-» Law of conservation of mass:-
According to law of conservation of mass, "mass can neither be created nor be destroyed during a chemical reaction."

-» Law of constant composition or definite proportion:-
According to this law "A chemical compound always contains the same elements combined together in the same proportion by mass."
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(ii.) -» Atomic weight:- Atomic weight is the average mass of atoms of an element.

-» Molecular weight:- Molecular weight is a measure of the sum of the atomic weight values of the atoms in a molecule. 

-» Gram Atomic Weight:- Gram atomic mass is the mass, in gram, of one mole of atoms in a monatomic chemical element. 

-» Gram molecular weight:- Gram molecular weightthe mass of one mole of a chemical compound equal in gram to the compound's molecular weight.

-» Average Number:- Average refers to the sum of numbers divided by n. Also called the mean average.
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HOPE THIS HELPS YOU:-))

Answer 2

Hi Sister,

Mainly there are 5 Laws of Chemical Combination:-

1. Law of Conservation of Mass:- This law was given by Lavoiser who is considered as father of Chemistry !

According to this law energy is neither created nor destroyed but converted from one form into another that is the mass of reactants should be always equal to mass of reactants.

Ex:- H₂ + O₂ ----> H₂O ( OR) 2H₂ + O₂----> 2H₂O

2) Law of Definite proportion:- It is also know as Law of Constant Proportion or Fixed Proportion

→It was given by Joseph Proust.

→According to this law when a substance is formed from same element they combine in fixed ratio of their weights.

Ex:- C + O₂ ---->CO₂
H₂O₂-----... H₂O + 1/2O₂

3) Law of Multiple Proportion:- This law was given by Dalton. 

→According to this law two elements combine to form different compounds by taking mass of one element fixed the other element will be simple ratio.

Ex:- 2H₂ + O₂----. 2H₂O
H₂ + O₂-->>>> H₂O₂

Ratio is 1:2 

4) Law of Reciprocal Proportion:- This law was given by Ritcher.

→According to this law when two substances combine with another substances to form a compound which bears simple ratio.

5) Law of Combining Volume:- This law was given by Gay- Lussac 

→According to this law, the gaseous reactants and products always bear simple ratio( considering their volumes)

Ex:- Ammonia 

N₂ + 3H₂---->>>> 2NH₃ ( 1:2:3)


Atomic Weight:- It is defined as weight of an element in it's atomic form or it is weight of an atom.

→It has no unit as it is a relative property 

Atomic weight= Weight of an atom/1/2 × C₁₂

→It is indicated by writing 'amu' ( Atomic mass unit ) 


Molecular Weight:- It is defined as weight of a molecule. It has no units.

Gram Atomic Weight:- It is defined as weight of an atom in grams it is also called gram atom.

Gram Molecular Weight:- It is defined as weight of gram molecule in grams it is also called gram molecule.

Avagadro number:-It is defined as 6.023 ₓ 10²³ particles( Atoms, molecule, ions)

→1 avagadro number is referred to as a mole.

→1 mole of an atom has weight equal to it's gram atomic weight.

→1 mole of a molecule has weight equal to it's gram molecule weight.

→1 mole of a gas occupies a volume of 22.4 litres or 22400 ml which is called gram molar volume.


Law of Reciprocal Proportion:- Example please see the below picture attached to the answer !!

Hope it helps you!