Download Measuring Matter - eChem2Bper2Miller

10.1-10.2 Notes
2/22/2008 11:35:00 AM
Measuring Matter
 Count how many you have of something
 Volume
o EX: purchasing gasoline
 Mass
o Ex: buying something using weight
 KEY CONCEPT
o You often measure the amount of something by one of the
three different methods, count, mass and volume
 Units
o By count
 EX: 1 dozen apples = 12 apples
o By mass
 EX: 1 dozen apples = 2.0 kg apples
o By Volume
 EX: 1 dozen apples = .2 bushel apples
o By knowing the units of these 3 different types of
measurements we can convert between them.
What is a mole?
 Mole: a unit that is a specified number of particles.
o 6.23 x 10^23 representative particles of that substance and
is the SI unit for measuring the amount of a substance.
 Avogadro’s Number
o Number of particles in a mole
 Representative Particle
o Species present in a substance…atoms, molecules of formula
units.

KEY CONCEPT: a mole of any substance contains Avogadro’s
number of representative particles.
The mass of a mole of an Element
 KEY CONCEPT: the atomic mass of an element is expressed in
grams is the mass of a mole of the element.
 Molar mass
o Mass of a mole in an element.
The mass of a Mole of a Compound
 Key Concept: to calculate the molar mass of a compound, find the
number of grams of each element in one mole of the compound.
Then add the masses of the elements in the Compound.
10.2
The Mole- Mass Relationship:
Key Concept: Use the molar mass of an element or compound to
convert between the mass of a substance and the moles of a
substance

Mass (grams) = Number of moles x Mass/ 1 mole
The Mole Volume Relationship:

Avogadro’s Hypothesis:
o

Equal volumes of gases at the same temperature and
pressure contain equal numbers of particles
Standard Temperature and Pressure (STP)
o
0 degrees Celsius and 101.3 kPa or 1 atmosphere
 Key Concept: At STP, 1 mol or 6.02 x 10^23 representative
particles, of any gas occupies a volume of 22.4 L

This quantity is called Molar volume
The Mole Road Map:

The mole is at the center of you chemical calculations, to do a
calculation the mole must be used as an intermediate step. The
form of the conversion factor depends on what you know and what
you want to calculate.
2/22/2008 11:35:00 AM
2/22/2008 11:35:00 AM