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There are only four conversions that you need to know
| molar mass (g)
mole |
mole
molar mass (g) |
6 x 1023 items
mole |
mole
6 x 1023 items |
| Determine each type of atom in the molecule |
|
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| Determine the number of each atom |
|
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| Determine the molar mass of each atom (g) |
|
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| Multiply the number of each atom by its mass |
|
2 x 35.45g = 70.90g |
| Add the masses together |
|
= 110.98g |
| Determine each type of atom in the molecule |
|
|
|
| Determine the number of each atom |
|
|
|
| Determine the molar mass of each atom (g) |
|
|
|
| Multiply the number of each atom by its mass |
|
1 x 32.06g = 32.06g |
|
| Add the masses together | 2.02g + 32.06g + | 64.00g = 98.08 g |
Moles
to Atoms or Molecules
A. Find the number
of atoms in 7 moles of Sodium.
7 moles
of Sodium (6.02 x 1023
atoms of Sodium) = 4.214 x 1024
atoms of Sodium
mole of Sodium
B. Find the number of
molecules in 3 moles of NaCl.
3 moles
of NaCl (6.02 x 1023
molecules of NaCl) = 1.806 x 1024
molecules of NaCl
mole of NaCl
C. Find the number of
molecules in 5 moles of carbon dioxide.
5 moles
of CO2 (6.02 x 1023
molecules of CO2) = 3.10 x 1024
molecules of CO2
mole of CO2
NOTE: Oxygen is one of seven
atoms that are always diatomic as elements.
D. Find the
number of atoms in 4 moles of Oxygen gas.
4 moles
of O2 (6.02 x 1023molecules
of O2)( 2 atoms of O
) = 4.816 x 1024 atoms of
Oxygen
mole of O2
molecules of O2
Return
Atoms
or Molecules to Moles
A. Find the number
of moles if you have 5.4 x 1023 atoms of carbon.
5.4 x 1024 atoms
of carbon (
mole of carbon ) = 9 moles of
carbon
6 x 1023 atoms of carbon
B. Find the number of
moles if you have 9.6 x 1024 molecules of KOH.
9.6 x 1024 molecules
of KOH (
mole of KOH )
= 16 moles of KOH
6 x 1023 molecules of KOH
Return
Grams
to Moles
A. Find the number
of moles if you have 302 g of CaCl2. Note: you must first
find the molar mass.
302 g
of CaCl2 ( mole of CaCl2
) = 2.72 moles of CaCl2
111 g of CaCl2
B. Find the number
of moles if you have 157 g of H2SO4. Note:
you must first find the molar
mass.
157 g
of H2SO4( mole of H2SO4
) = 1.60 moles of H2SO4
98 g of H2SO4
Return
Moles
to Grams
A. Find the mass if
you have 14.00 moles of CaCl2. Note: you must first find
the molar mass.
14.00 moles
of CaCl2 (
111-g of CaCl2 ) = 1554-g of CaCl2
mole of
CaCl2
B. Find the mass if
you have 8.30 moles of H2SO4. Note: you must
first find the molar mass.
8.30 moles
of H2SO4( 98 g of H2SO4
) = 813-g of H2SO4
mole of H2SO4
Return
Grams
to Number of Atoms or Molecules
A. Find the number
of molecules if you have 4.37-g of CaCl2. Note: you must
first find the molar mass.
4.37 g
of CaCl2 (mole
of CaCl2)(6.02
x 1023 molecules of CaCl2)
= 2.37 x 1022 molecules
of CaCl2
(111 g of
CaCl2)
(mole of CaCl2)
B. Find the number of
chloride
ions if you have 4.37-g of CaCl2. Note: you must
first find the molar mass.
4.37 g
of CaCl2 (mole
of CaCl2)(6.02
x 1023 molecules of CaCl2)(
2 ions of Cl ) = 4.74
x 1022 chloride ions
(111 g of
CaCl2)
(mole of CaCl2)
(molecules of CaCl2)
C. Find the number of
oxygen
ions if you have 32.1-g of H2SO4. Note:
you must first find the molar
mass.
32.1 g
of H2SO4 (mole
of H2SO4)(6.02
x 1023 molecules of H2SO4)(
4 ions of O ) = 7.89
x 1023 oxygen ions
(98 g of
H2SO4)
(mole of H2SO4)
(molecules of H2SO4)
Return
Number
of Molecules or Atoms to Grams
A. What is the mass
of 8.26 x 1021 atoms of carbon?
8.26 x 1021 atoms
of C (
moles of C
)(12.01-g of C) = 0.165 g of Carbon
(6.02 x 1023 atoms of C)
(mole of C)
B. What is the mass
of 10,000 molecules of CaCl2?
10,000 molecules
of CaCl2 (
moles of CaCl2
)(111-g of CaCl2 )
= 1.84 x 10-18 g of CaCl2
(6.02 x 1023 molecules of CaCl2)(moles
of CaCl2)
Return
Balancing
a Chemical Equation
A chemical reaction has the reactants
(or substrates) on the left side and the products on the right side.
In chemical reactons:
a) The mass of the reactants must
be equal to the mass of the products.
b) The same number of each kind
of atom appears on each side of the arrow
c) The arrangement of atoms in reactants
is not the same as it is in the products of a chemical reaction.
To balance the chemical equation:
a) write the correct chemical formula
for each reactant and for each product.
b) adjust the numbers before each
molecule's formula until the atoms are conserved.
1) always start
with the atom that is limiting on one side
2) continue adjusting
until atoms are conserved
A. Find the balanced equation for the decomposition of water into hydrogen and oxygen.
|
Note: <> means not equal to |
has 2H + 1O <> 2H + 2O |
| Adjust number limiting of reactant
atoms of O
|
4H + 2O <> 2H + 2O |
| Adjust number limiting of product
atoms of H
|
4H + 2O = 2H + 2O |
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|
|
|
number of atoms Note: <> means not equal to |
has 2N + 2H + 6O <> N + H + 3O |
| Adjust number limiting of product
atoms of O
|
has 2N + 2H + 6O = 2N + 2H + 6O |
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Stoichiometry
A. A variety of phosphorus
called red phosphorous is used in match heads. When 0.062
grams of red phosphorus burns with oxygen, 0.142
grams of phosphorus oxide is formed. What is the empirical formula
for this oxide?
| Mass of Phosphorus used |
|
| Molar mass of Phosphorus |
|
| Moles of Phosphorus used | 0.062 (31.0 |
| Mass of Oxygen used |
|
| Molar mass of Oxygen |
|
| Moles of Oxygen used | 0.08 (16.0 |
| Molar Ratio - P:O | P = (0.002 moles
of P) = 2P --> P2O5
O (0.005 moles of O) 5O |