The Mole Mass & The Mole Ch CHM Hon.

How do you measure matter? Measure the amount by: –Counting –Mass –Volume

Measuring Matter Different forms of measurement relate –1 dozen apples = 12 apples –2.0 kg apples = 1 dozen apples –1 dozen apples = 0.2 bushel apples

Finding Mass from a Count What is the mass of 9 average- sized apples if 1 dozen apples has the mass of 2.0 kg? 15 kg

Finding Mass from a Count If 0.20 bushel is 1 dozen apples and a dozen apples has a mass of 2.0 kg, what is the mass of 0.5 bushel of apples? 5.0 kg

What is a mole? Remember: Matter is composed of atoms, molecules and ions Mole (mol) –6.02 x representative particles of that substance –The SI Unit for measuring the amount of a substance

What is a mole? Avogadro’s number –The number of representative particles in a mole –6.02 x –Avogadro ( ): Italian scientist who helped clarify the difference between atoms and molecules

The Representative Particle Refers to the species present in a substance –Usually atoms, molecules or formula units –The representative particle of most elements is the atom –Sometimes the representative particle is a molecule ex) Molecular compounds (H 2 O) 7 elements normally exist as diatomic molecules –H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2

The Representative Particle –A mole of any substance contains Avogadro’s number of representative particles (6.02 x )

Converting Number of Particles to Moles 1 mol = 6.02 x representative particles Conversion Factor:

Converting Number of Particles to Moles

0.208 mol Mg

How many moles is 2.8 x atoms of silicon? 4.65 mol Si

Converting Moles to Number of Atoms 1.40 x atoms

amu Remember that atomic mass of an element (the mass of a single atom) is expressed in atomic mass units! –Relative values based on C-12 atom C-12 atom = Mass 12 amu H atom = Mass 1 amu

Atomic mass & Molar mass Molar mass = the mass of a mole of an element The Atomic mass of am element expressed in grams is the mass of a mole of the element –Carbon: molar mass = 12 g –Hydrogen: molar mass = 1 g –Sulfur: molar mass = ? –Mercury: molar mass = ? 32.1 g g

Molar mass is the mass of 1 mol of atoms of any element!! Magnesium (Mg): 1 mol Mg  6.02 x atoms Mg  Molar mass 24.3 g

Determining the Mass of a Mole of a Compound First step: determine the molecular formula –Ex) Sulfur trioxide: Second step: calculate the mass of the molecule –Add the atomic masses of the atoms

Finding the Molar Mass of a Compound 34.0 g

Finding the Molar Mass of a Compound Find the molar mass of PCl g

Mole to Mole conversion 13.1 mol Ca

Determine the number of moles in 25.5 g Ag mol Ag

Mass to Atoms Conversion

How many atoms are in 55.2 g Li? 4.79 x atoms Li

Atoms to mass Conversion g He

What is the mass in grams of 6.02x10 24 atoms Bi 2.09 x 10 3 g Bi

I am so confused!? Putting it into prospective… MASS  MOLES  REP. PARTICLES