Chapter 4: The Mole

• there is a constant ratio in equal volumes of different gases

Ex:

    Oxygen             : Hydrogen
    Carbon Dioxide: Hydrogen
    Carbon Dioxide: Oxygen

Avogadra's Hypothesis

Different gases will have the same number of particles if they are also at the same temperature and pressure.
This means...
                    if they have the same amount of particles, the mass ratio is due to the mass of the particles.
 The mass of 1 atom of the element in atomic mass units (amu/u/daltons)

Formula MassAll atoms of a formula of an ionic compound (in amu)

Ex:     
     Potassium Flouride
     K             F
     39.1+19.0=
     KF= amu

Molecular MassAll atoms of a formula of a covalent compound (in amu)

Ex:     Carbon     Dioxide
     C               O²
     12.0          16.0x2
     CO²= 44.0 amu

Atomic/molecular/formula mass of any pure substance
        (in grams per mol)

Ex:      1 mole of Oxygen= 16.0 g/mol
        "      "     Carbon= 12.0 g/mol
        "       "    Potassium= 39.1 g/mol

Avogadra's Number

The number of particles in 1 mole of any amount of substances is...

 

         6.022x10^²³ particles

                                    mol

The mole is important and very useful to chemists because it enable them to count atoms and molecules

Take a look at this link for a brief explanation about Avogadra's number:

http://www.youtube.com/watch?v=AsqEkF7hcII 

By Lauren