Transcript Molar mass of H = 2

Moles and Molarity
Stoichiometry and Moles
Stoichiometry and Moles
Moles
• Moles are counting
units used in chemistry
• Moles measure the
• 2CuO + C = 2Cu + CO2
amount of the very tiny
2 moles + 1mole = 2 mole + 1 mole
particles (atoms and
molecules) that make Copper Oxide Carbon Copper Carbon
Dioxide
up matter
• The mole is a unit of
measurement used in
chemistry to express
amounts of a chemical
substance, defined as
the amount of any
substance that contains
as many elementary
entities (e.g., atoms,
molecules, ions,
electrons)
Moles
• 1 mole of water
molecules is
602 000 000 000 000 000
000 000 molecules.
That’s 602 septillion
molecules, but written
in scientific notation it
equals
6.022 X 1023
Moles
• 1 mole of water
molecules is
602 000 000 000 000 000
000 000 molecules.
That’s 602 septillion
molecules, but written
in scientific location it
equals
6.02 X 1023 = the number of
atoms or molecules in 1 mole of
substance.
Moles
• 1 mole of water molecules is
602 000 000 000 000 000 000 000
molecules.
That’s 602 septillion molecules, but
written in scientific location it equals
6.02 X 1023 = the
number of atoms or
molecules in 1 mole of
substance.
This amount is called:
Avogadro’s number
Scientific Notation
• For displaying very large
and very small
numbers.
• All numbers changed to
2-3 digit power of 10.
1,000,000 = 1 x 106
• 1,000 = 1 x 10?
• .0000000001 = 1 x 10?
Scientific Notation
• For displaying very large
and very small
numbers.
• All numbers changed to
2-3 digit power of 10.
1,000,000 = 1 x 106
• 1,000 = 1 x 103
• .0000000001 = 1 x 10-10
Scientific Notation
• When multiplying with
scientific notation, you
add the exponents
• 1,000,000 x 1,000
• 1 x 106 x 1 x 103 =
• 1 x 109
• When dividing with
scientific notation, you
subtract the exponents
Scientific Notation
• When multiplying with scientific
notation, you add the exponents
• 1,000,000 x 1,000
• 1 x 106 x 1 x 103 =
• 1 x 109
• When dividing with
scientific notation, you
subtract the exponents
• 1 x 106 = 106-3 = 1 x 103
• 1 x 103
Mole
• The large number of
particles allows this
amount of atoms,
molecules, or formula
units to be weighed and
measured.
• The atomic weight of an
element can be used to
measure the mass of
one mole of a
substance
Mole
• The large number of
particles allows this
amount of atoms,
molecules, or formula
units to be weighed and
measured.
• The atomic weight of an
element can be used to
measure the mass of
one mole of a
substance
Molar Mass
• Molar mass is used to
measure the amount in
grams of a substance
that makes up 1 mole of
atoms.
• 1 mole of an element is
the same as its Atomic
Weight
• Molar mass =
grams/mole = atomic
mass
One mol C = 12.01 g C
or 12.01 g/mol
One mol Cu = 63.55 g Cu
or 63.55 g/mol
Molar mass of compounds
• The molar mass of
compounds or
1 mol C X 12.01 g C = 12.01 C
molecules is the sum of
1 mol C
the molar masses of its
2 mol O X 16.00 g O = 32.00 O
atoms
1 mol O
• The molar mass of CO2
Molar mass of CO2 = 12.01 g + 32.00 g
contains one mole of C
= 44.O1 g CO2
and 2 moles of Oxygen
Factor method
• Factor Method
• Units/equivalents are
placed in fraction form
and used to crosscancel till desired unit
(answer) is reached.
• Unit to be removed is
the reciprocal fraction
• How many mm in 10
km?
• 10 km X___m X __mm
1
1 km 1 m
Factor method
• Factor Method
• How many mm in 10 km?
• Units/equivalents are
placed in fraction form
and used to crosscancel till desired unit
• 10 km X 1000m X 1000mm
(answer) is reached.
1
1 km
1 m
• Unit to be removed is
the reciprocal fraction
Factor method
• How many seconds in 2 days?
• 2 days X ________hr X _______min X ______sec
1
day
1
hr
1
min
• Calculate the molar mass of water H2O
2 mol H X
g H = ______ g H
1 mol H
1 mol O X
g O = ______ g O
1 mol O
Molar mass H2O = ______ + _____ =
Factor method
• How many seconds in 2 days?
• 2 days X ________hr X _______min X ______sec
1
day
1
hr
1
min
• 2 days X ___24_____hr X __60___min X 60____sec
1
day
1
hr
1 min
Calculating molar mass
• Calculate the molar
mass of Sodium (Na)
1 mol Na X
g Na = ______ g Na
1 mol Na
• Calculate the molar mass of
water H2O
2 mol H X
• Calculate the molar mass of
Iron (Fe)
g H = ______ g H
1 mol H
1 mol O X
g O = ______ g O
1 mol O
Molar mass H2O = ______ + _____ =
• Calculate the molar mass of
Silicon Dioxide ( SiO2)
Factor method
• How many seconds in 2 days?
• 2 days X ________hr X _______min X ______sec
1
day
1
hr
1
min
• Calculate the molar mass of water H2O
2 mol H X
g H = ______ g H
1 mol H
1 mol O X
g O = ______ g O
1 mol O
Molar mass H2O = ______ + _____ =
Find the molar masses of the following compounds
1)
Nitrogen atoms, N1 mole N X _____ g N
N=
g/mol
2)
Nitrogen molecules, N2
3)
Sodium Chloride (salt), NaCl
4)
Sucrose (table sugar), C12H22O11
5)
Baking Soda , NaHCO3
=
_____g N
1 mole N
Calculating moles
• How many moles are in
32 grams of Oxygen?
32 g O X 1 mol O
___ g O
= ______ moles O
• How many moles are in
32 grams of CO2
Calculating moles
• How many moles are in
32 grams of Oxygen?
32 g O X 1 mol O
___ g O
= ______ moles O
• How many moles are in
32 grams of CO2
Calculating mass
• How many grams are in
2 moles of Oxygen?
2 mol O
1
x ___ g O
1 moles O
=
• How many grams are in
3 moles of CO2?
___ g O
Calculating mass
• How many grams are in
2 moles of Oxygen?
2 mol O
1
x ___ g O
1 moles O
=
• How many grams are in
3 moles of CO2?
___ g O
Calculating Percent composition
Percent composition uses
the molar mass of the
component parts of
molecules or compounds
to determine the % or
portion of each
component to the whole
compound.
• Calculate the molar
mass of H20 (water) and
then use this
information to calculate
the % composition of
hydrogen (H) and
oxygen (O) in H20
Calculating Percent composition
Percent composition uses
the molar mass of the
component parts of
molecules or compounds
to determine the % or
portion of each
component to the whole
compound.
Molar mass of H2O =
H = 2x
O=
H2O =
Calculating Percent composition
• % composition of H
Molar mass of H
Molar mass of H2O
x 100 = % H
Molar mass of O x 100 = % O
Molar mass of H2O
Molar mass of H2O =
H = 2x 1 = 2 O = 16
H2O = 18
Calculating Percent composition
• % composition of H
Molar mass of H
Molar mass of H2O
x 100 = % H
Molar mass of O x 100 = % O
Molar mass of H2O
Molar mass of H2O =
H = 2x 1 = 2 O = 16
H2O = 18
Calculating Percent composition
• % composition of H
Molar mass of H = 2 x 100 = % H
Molar mass of H2O = 18
Molar mass of O = 16 x 100 = % O
Molar mass of H2O = 18
Molar mass of H2O =
H = 2x 1 = 2 O = 16
H2O = 18
Calculating Percent composition
• % composition of H
H = 2 = .111 x 100 = 11.1 % H
H2O = 18
O = 16 = .889 x 100 = 88.9 % O
H2O = 18
Hydrogen makes up 11.1 % and Oxygen
makes up 88.9% by mass of 1 water
molecule
Molar mass of H2O =
H = 2x 1 = 2 O = 16
H2O = 18
Calculating Percent composition
• What is the %
composition of C and O in
CO2 ?
Molar mass of C =
Molar mass of CO2 =
Molar mass of O =
Molar mass of CO2 =
x 100 = % H
x 100 = % O
Molar mass of CO2 =
C = O = 2x =
CO2 =
Calculating Percent composition
• What is the %
composition of C and O in
CO2 ?
C =
CO2 =
O =
CO2 =
x 100 =
x 100 =
%C
%O
Molar mass of CO2 =
C = O = 2x =
CO2 =
Equations and Molar Mass
• Chemical equations can
be used to determine
mass relationships
between reactants and
products.
• The proportional or
mass based method can
be used to determine
reactant and product
mass
• Burning carbon and carbon
containing compounds in air can
produce carbon monoxide. This is
one reason why carbon monoxide
detectors are used
2 C(s) + O2(g) ----> 2 CO(g)
• The equation says that two moles
of carbon react exactly with one
mole of oxygen. The coefficients
in the balanced equation tell the
moles of each substance involved
in the equation.