LAW OF CHEMICAL COMBINATIONS:
1)Law of Conservation of Mass:
It states that "matter can neither be created nor destroyed".
2)Law of Definite Proportions:
It stated that "a given compound always contains exactly the same proportion of elements by weight".
Example : Oxygen and hydrogen in water always bear ratio of 16:2 or 8:1 by mass.
3)Law of Multiple Proportions:
According to this law, "if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers".
Example
Hydrogen + Oxygen — Water
2g 16g 18g
Hydrogen + Oxygen — Hydrogen Peroxide
2g 32g 34g
Here, the masses of oxygen (i.e. 16 g and 32 g) which combine with a fixed mass of hydrogen (2g) bear a simple ratio, i.e. 16:32 or 1: 2.
4)Gay Lussac's Law of Gaseous Volumes:
when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at same temperature and pressure.
Example:
Hydrogen + Oxygen — Water
100 mL 50 mL 100 mL
Thus,
the volumes of hydrogen and oxygen which combine together (i.e. 100 mL and 50 mL) bear a simple ratio of 2:1
5)Avogadro Law:
Avogadro proposed that equal volumes of gases at the same temperature and pressure should contain equal number of molecules.
Example .
Hydrogen + Oxygen — Water
we see that two volumes of hydrogen combine with one volume of oxygen to give two volumes of water without leaving any unreacted oxygen.
DALTON'S ATOMIC THEORY:
1. Matter consists of indivisible atoms.
2. All the atoms of a given element have identical properties including identical mass. Atoms of different elements differ in mass.
3. Compounds are formed when atoms of different elements combine in a fixed ratio.
4. Chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.
5.Dalton's theory could explain the laws of chemical combination.
1)Law of Conservation of Mass:
It states that "matter can neither be created nor destroyed".
2)Law of Definite Proportions:
It stated that "a given compound always contains exactly the same proportion of elements by weight".
Example : Oxygen and hydrogen in water always bear ratio of 16:2 or 8:1 by mass.
3)Law of Multiple Proportions:
According to this law, "if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers".
Example
Hydrogen + Oxygen — Water
2g 16g 18g
Hydrogen + Oxygen — Hydrogen Peroxide
2g 32g 34g
Here, the masses of oxygen (i.e. 16 g and 32 g) which combine with a fixed mass of hydrogen (2g) bear a simple ratio, i.e. 16:32 or 1: 2.
4)Gay Lussac's Law of Gaseous Volumes:
when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at same temperature and pressure.
Example:
Hydrogen + Oxygen — Water
100 mL 50 mL 100 mL
Thus,
the volumes of hydrogen and oxygen which combine together (i.e. 100 mL and 50 mL) bear a simple ratio of 2:1
5)Avogadro Law:
Avogadro proposed that equal volumes of gases at the same temperature and pressure should contain equal number of molecules.
Example .
Hydrogen + Oxygen — Water
we see that two volumes of hydrogen combine with one volume of oxygen to give two volumes of water without leaving any unreacted oxygen.
DALTON'S ATOMIC THEORY:
1. Matter consists of indivisible atoms.
2. All the atoms of a given element have identical properties including identical mass. Atoms of different elements differ in mass.
3. Compounds are formed when atoms of different elements combine in a fixed ratio.
4. Chemical reactions involve reorganization of atoms. These are neither created nor destroyed in a chemical reaction.
5.Dalton's theory could explain the laws of chemical combination.
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