Laws of chemical combinations
1) Law of conservation of mass:- According
to this law “matter can neither be created nor destroyed” Given by Antone Lovoisin in 1789.
2) Law of definite proportion:-
According to this law “A given compound always contains exactly the same
proportion of elements by weight known as law of definite proportion or law of definite composition” given by Joseph Proust in 1754-1826
3) Law of multiple proportion:-
According to this law “if two elements combine to form more than one compound,
the masses of one element that combine with a fixed mass of small whole number”
given by Dalton in 1803.
4) Gay lussac’s law of gaseous volume:- According
to this law “gases combine or are produced in chemical reactions they do so in
a simple ratio by volume provided to all gases are at the same temperature and pressure” given by Gay Lussac’s in 1808.
5) Avogadro’s law:- According
to this law “Equal volume of gases at same temperature & pressure should
contain equal no. of molecules” given by Avogadro
in 1811.
Dalton’s Atomic Theory
ii.
All the atoms of a element have identical
properties (same properties) i.e. atoms of a element have same mass while atoms
of different elements have different masses.
iii .
Compounds formed when atoms of different
elements combine in fixed ratio.
iv.
Chemical reactions involve reorganization
(rearrangement) of atoms.
Atomic mass unit = 1/12th
mass of one carbon12 atom.
Molecular mass = It is
the sum of atomic masses of the elements present in a molecule.
Mole :- It is the
amount of substance equal to Avogadro no. (NA). = 6.022 ´ 1023 atoms/mole.
Molar mass:- Mass of
one mol of a substances in gram is known as molar mass.
Mass % of an element =
mass of that element in compound ´
100/ molar mass of the compound.
Empirical formula :- It
is the simplest whole no. ratio of various atoms present in a compound.
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