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Ch 7.1 Counting Units
One dozen = 12 things
We use a dozen to make it easier to count the amount of substances.
Molesthe SI base unit that describes the number of particles in a substance.
Mole is abbreviated mol
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/moleday.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/moleday.mp4
So what does a Mole equal?Avogodro’s constant is the amount of particles in one mole of a substance.
He found that 6.02x1023 is the amountparticles are always found in one mole
This amount is exactly equal to the amount of 1.0 mole.
MolesUsed by chemist when counting large numbers of tiny particles such as atoms
One mole of anything will equal the same amount of particles.
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/laser disc videos/CheMedia/moles.mpg
../../videos/austinpowersmole.mp4../../videos/austinpowersmole.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/austinpowersmole.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/austinpowersmole.mp4
Ch. 7.2 Molar MassThe mass in grams of 1 molof any substance.
Using the periodic chart you can determine the molar mass of any element or compound.
g/ 1 mole
6.02 x 1023 particles
Ch. 7.3 Molar Mass Calculations
Chemists must use mole calculations in order to prepare reactions.
They act as recipes for chemists.
EXAMPLE PROBLEM #1How many grams of Calcium fluoride must a chemist prepare if the reaction requires 4.0 moles of calcium fluoride?
SolutionThe molar mass of CaF2 is 78 g/1 mol.
4.0 moles CaF2 x 78.0 grams CaF2 =
1 mole CaF2
310 g CaF2
Example Problem #2How many moles were produced if your reaction yielded 92.0 grams of sodium sulfate?
SolutionMM of Na2(SO4) is 142 g/1 mole92.0 g Na2(SO4) x 1 mole Na2(SO4) =
142.0 g Na2(SO4)
0.648 moles Na2(SO4)
Example Problem #3How many molecules were produced if your reaction yielded 12.0 grams of Carbon monoxide?
Solution
MM of CO is 28 g/1 mole12.0 g CO x 6.02x1023molecules CO
28.0 g CO
= 2.58x1023 molecules CO
Ch. 7.4 Percent Composition
A measurement that measures the amount of each element in the total compound.
Can be used to determine the amount recovered from a compound breaking down
Hydrogen
Nitrogen
Oxygen76%
22%
2%HNO3
Percent Composition
How many grams of silver can be recovered by decomposing 32 grams of silver oxide?
Calculating Empirical FormulaA compound is made from 30.5% nitrogen and 69.5% oxygen. What is the empirical formula?
Assume you have a 100 gram sample
30.5 g N/ 14.0 gram per mole = 2.2 moles N
69.5 g O/ 16.0 grams per mole = 4.3 mole O
2.2 mole N/ 2.2 mole = 1 N
4.3 mole O/2.2 mole = 2 O
Formula is NO2
Empirical Formula
• A lab determines that a compound found in water contains 66.0% calcium and 34.0 % phosphorous. What is the identity of the compound?
Ch. 7.5 Determining Molecular Formula
The empirical formula is nitrogen dioxide. Its actual molar mass is 184 g/mole. What is the molecular formula?
Molar mass of NO2 is 46 g/ mole.
184g / 46.0g = 4
NO2 x 4 = N4O8
Ch 8.1 Chemical Reactions
•When substances undergo
chemical changes, they
form new substances.
•Atoms are rearranged,
because bonds are broken
and reformed
Chemical Reactions
• Signs are:
1. evolution of heat and light
2. color change
3. gases emitted
4. a precipitate forms (solid
residue)
Equation Make-up
•Reactants
substances that
will undergo a
chemical change.
(Left side)
Equation Make-up
•Products
substances that
are formed as a
result of a
chemical change.
(Right side)
Recipes:
• 1 cup batter +1/2 cup water + 2 eggs → 4 pancake
6CO2
+6H2O→C
6H
12O
6 + 6O
2
ReactantsProducts
Ch. 8.2 Balancing
• All equations must have the
same type and number of atoms
on each side of the equation.
• Law of Conservation of Mass
• Tells you the amounts
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/Chem. Music Videos/Chemistry_Music_Video_19___Don_amp
Beaker Violating Law of
Conservation of Mass
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/Beaker violates Conservation of mass.mp4
Mole Ratios
• Coefficients show the amount of
moles of each substance.
• Mole ratio is the smallest
relative number of moles of the
substance involved in a
reaction.
• 2H2
+ O2
→ 2H2O = 2:1:2
Rules to Balancing
• Can only change coefficients
and never subscripts.
• Always balance H and O last if
water is in the equation.
• In a double displacement
reaction, balance the ions.
• (OH)-= H
2O
Writing Complete
Equations
• Phase identification
• s, l, g, v, aq
• Solutions and acids are mixed
with water, so are considered
aqueous.
• All ionic compounds are solids or
aqueous
• Remember which ELEMENTS are
diatomic
Ch. 8.3
Reaction Types
• 5 types of reactions
1. Synthesis Reaction
(combination RXN)
•A reaction when two
substances form at
least one new, more
complex compound.
Synthesis Reaction
• EXAMPLE:
A + B A B
2Fe + O22FeO
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/potassiumchlorine.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/potassiumchlorine.mp4
• Zn + S → ZnS
• Al + Br2
→ AlBr3
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/zincsulfur.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/zincsulfur.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/brominealuminum2.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/brominealuminum2.mp4
2. Decomposition Reaction
•A reaction in which
one compound breaks
into at least two
products.
Decomposition Reaction
EXAMPLE:
AB A + B
2 NI3 N
2+ 3I
2
2 H2O
2 2 H
2O + O
2
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/laser disc videos/CheMedia/NI3.mpgC:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/NI3.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/NI3.mp4
Decomposition
of Sugar
C6H
12O
6→ C + H
2O
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/laser disc videos/Science is fun/dehydration sugar.mpgC:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/laser disc videos/Science is fun/dehydration sugar.mpg
3. Single displacement Reaction
•A reaction in which
atoms of one element
take the place of ions
of another
compound.
Single displacement Reaction• Example
X A + B B A + X
3CuCl2 + 2Al
2AlCl3 + 3Cu
• Fe2O
3+ 2Al → 2Fe + Al
2O
3
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/ironoxide and aluminum.mp4C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/ironoxide and aluminum.mp4
4. Double Replacement Reaction
• A reaction in which the apparent exchange of ions between two compound solutions.
Double replacement reaction
AX + BY AY + BX
Pb(NO3)2
+K2(CrO
4)
→
Pb(CrO4) + 2K(NO
3)
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/doubledisplacement.mp4
5. Combustion reaction
•Reaction in which an
organic compound
and oxygen burn.
•Oxygen always is a
reactant
Combustion reaction
•CO or CO2
will
always be a product
• H2O will always be a
product
Combustion reaction
C2H
50H + 3O
2
2CO2
+ 3H2O
MUPPET LABS
C:/Users/tglenn/OneDrive @ Manasquan School District 1/classes/videos/chemistry/The Muppet Show Muppet Labs - Fireproof Paper.mp4
Stoichiometry
Ch. 9.1
• Calculations dealing with the amounts
of substances needed or produced in
a chemical reaction.
• Mole-mole problems
• Mass-mass problems
• Percent Yield
Stoichiometry
Ch. 9.1
• Steps to solving:
1. Balance the chemical equation
2. Determine the mole ratio needed for
problem
3. Determine # of steps
4. Use Dimensional Analysis to solve
Stoichiometry
Mole-mole Problem
• How many moles of sodium nitrate
can be produced from the reaction of
0.67 moles of calcium nitrate with
excess sodium chloride?
2NaCl + Ca(NO3)2 → CaCl
2+ 2NaNO
3
0.67 moles Ca(NO3)2
x 2 mole Na(NO3)
1mole Ca(NO3)2
= 1.3 moles of Na(NO3)
Ch 9.2 Stoichiometry
Mass-mass Problem
• How many grams of
magnesium oxide could be produced
from 9.90 g of magnesium reacting
with an excess of oxygen gas?
• 2Mg + O2
→ 2MgO
9.90 grams Mg x 1 mole Mg x 2 mole MgO x 40.0 g MgO
24 g Mg 2 mole Mg 1 mole MgO
= 16.5 grams of MgO
Ch. 9.4 Stoichiometry
Percent Yield
• The actual amount of product
expressed as a percentage of the
calculated theoretical yield of that
product.
• The theoretical amount is what is
calculated using Stoichiometry
• Percent Yield = actual amount of product x 100%
theoretical amount of product
Stoichiometry
Percent Yield Problem
• What is the percent yield in the following
reaction if 5.50 grams of hydrogen reacts
with nitrogen to form 20.4 grams of
ammonia?
• N2
+ 3H2
→ 2NH3
5.50 g H2
x 1 mole H2
x 2 mole NH3
x 17 g NH3
2 g H2
3 mole H2
1 mole NH3
= 31.2 grams of NH3
• 20.4 g /31.2g x 100% = 65.4%