Chemical Changes                                         Mole Concept
    These affect the composition as well as                 It is defined as the quantity of a substance
     chemical properties of matter and result in              that has the same number of particles as
     the formation of a new substance.                        are found in 12 grams of carbon-12.
    e.g. of chemical changes include                        The number of atoms present in 12 grams
     combustion (burning), cooking an egg,                    of carbon 12 (C-12) which is equal to
     rusting of an iron pan, and mixing                       6.023 X 1023. This is also known as
     hydrochloric acid and sodium hydroxide                   Avogadro"s constant.
     to make salt and water.                                 1 mol = 6.023 X 1023 = Avogadro"s
                                                              Number or Constant
Physical Changes
                                                             Atomic mass : It is the mass of one atom
    It is the change which only affect the                   of that element in atomic mass units (u).
     physical properties like colour: hardness,              Molar mass : It is equal to the numerical
     density, melting point etc. of matter.                   value of the atomic mass. Its unit is g. The
    It does not affect the composition and                   molar mass of an atom is also known as
     chemical properties of matter.                           gram atomic mass.
    e.g. of physical changes include crushing a             Molecular mass : It is the sum of the
     can, melting an ice cube, and breaking a                 atomic masses of all the atoms in a
     bottle.                                                  molecule of a substance.
                                                             Formula unit mass : It is the sum of the
                                                              atomic masses of all atoms in a formula
                                                              unit of a compound. It is used for
                                                              substances made up of ions.
                                       THE GAS LAWS
    PRESSURE VOLUME TEMPERATURE RELATIONSHIPS
Where P is the pressure, V is the volume of a gas, T is the absolute temperature, n is the number of
moles of the gas, k is the constant and R is the universal gas constant.
Boyle"s Law: The Pressure-Volume Law
It states that, at constant temperature, the             Charles" Law:        The Temperature-Volume
pressure of a fixed amount of gas (number of             Law
moles) is inversely proportional to its volume.
                                                         It states that, at constant pressure volume of a
     1
P  or PV  k
                                                         fixed mass of a gas is directly proportional to
     V                                                   its absolute temperature.
or P1V1  P2 V2
                                                          VT
When pressure goes up, volume goes down.                     V
                                                          or   k
When volume goes up, pressure goes down.                     T
                                                             V    V
                                                          or 1  2
                                                             T1 T2
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