Download Unit 2 PowerPoint part 2

*
Mr. Kinton
Honors Chemistry
* What’s a Mole?
* The mole allows us to quantitatively
understand how chemical reactions take place
* Before we begin we need to examine some
quantitative values pertaining to reactions
*
*Atoms of the same element (same # of
protons), but with different numbers
of neutrons.
*Have different mass numbers (and
masses)
*Isotopes behave the same chemically
because they still have the same
number of protons and electrons
*
Subatomic 12C
Particles
13C
14C
Protons
6
6
6
Electrons
6
6
6
Neutrons
6
7
8
*
* The actual masses of protons, neutrons and
electrons are all very small
* Therefore, we compare the relative masses of
atoms
* All relative to a reference isotope as a standard
* Scientists picked Carbon-12 as the reference
isotope
* Carbon-12 has a standardized mass of 12 amu
(atomic mass units)
*
*The weighted average mass of the atoms
in a naturally occurring sample of the
element
***Have to take isotopes and their relative
abundances into account
*
Element X has 2 natural isotopes. The isotope with a
mass of 10.012amu (10X) has a relative abundance of
19.91%. The isotope with a mass of 11.002amu (11X)
has a relative abundance of 80.09%. Calculate the
atomic mass of this element.
Atomic mass= (m1)*(abundance1)+(m2)*(abundance2)
100
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* Which isotope of copper is more abundant:
copper-63 or copper-65?
*
* An element is just its atomic weight
* F2- (2 x 19.00)= 38.00 amu
* K- 39.10 amu
* The sum of the atomic weights of each atom
* H2SO4(aq)- (2 x 1.008) + (32.07) + (4 x 16.00)=
98.09 amu
*
* Applies specifically to
* Applies specifically to
* C6H12O6- (6 x 12.01) + (12 x
* NaCl- 22.99 + 35.45 = 58.44
compounds containing only
nonmetals
1.008) + (6 x 16.00) = 180.2
amu
* Units are in amu
*
compounds containing
metals and nonmetals
amu
* Units are in amu
* Calculate the formula weight of each
compound and identify if it as a formula unit or
a molecular weight:
* C12H22O11
* Ca(NO3)2
* Al(OH)3
* CH3OH
*
* Amount of matter that contains as many
objects as 12g of Carbon-12
* Avogadro’s Number- 6.02 x 1023 (molecules,
atoms, ions, particles)
* 1 mole Carbon-12 atoms = 6.02 x 1023 atoms
* 1 mole of H2O molecules = 6.02 x 1023
molecules
* 1 mole NO3- ions = 6.02 x 1023 ions
*
* A mole is always 6.02 x 1023
* The mass of a mole can be different
* 1 atom of Carbon-12 has a mass of 12 amu
* 1 mol of Carbon 12 has a mass of 12g
* 1 atom of Magnesium-24 has a mass of 24 amu
* 1 mol of Magnesium-24 has a mass of 24g
* Given in g/mol
* Has the same numerical value as the formula
weight
* H2O = 18.02 g/mol
* Na = 22.99 g/mol
* Ca(NO3)2 = 164.1 g/mol
*
* Calculate the molar mass of the following:
* Ag
* I2
* CO2
* Fe2O3
*
* How many atoms are in 3g of Cu?
* 3g Cu 1 mol Cu 6.02 x 1023 Cu atoms
63.5g
1 mole
* 3 x 1022 Cu atoms
* How many grams are in 4.01 x 1022 molecules of
HNO3
* 4.01 x 1022 molecules 1 mole
63.02g
6.02 x 1023 1 mole
* 4.20 g
*
* How many moles are in 5.380g of C6H12O6
* 5.380g 1 mol
180.16g
* 0.02986mol
* How many grams are in .433 mol Ca(NO3)2
* .433 mol 164.1g
1 mol
* 71.1g
*
* Using dimensional analysis determine the
following quantities:
* Grams of NaHCO3 in 6.33 mol
* Moles of H2SO4 in 2.9 x 10-3g
* Atoms of Oxygen in 4.20g of HNO3
* Moles of C6H12O6 in 1.75 x 1022 molecules
*
* Percent mass contributed by each element
* Comparison between calculated and
theoretical values
* Let’s examine glucose or
C6H12O6
*
* Calculate the percent composition of Nitrogen
in Ca(NO3)2:
*
* Tells the relative number of atoms in a
compound
* Use percentages to determine the number of
atoms of each element
* Empirical formulas always contain the lowest
whole number ratios of atoms
*
* 1. Mass % of elements
* 2. Grams of each element
* 3. Moles of each element
* 4. Divide by small to get the Empirical formula
* Ascorbic Acid contains 40.92% C, 4.58% H, and
54.50% O by mass. Determine the empirical
formula
*
* Always a whole number multiple of the
empirical formula
* Must know the molecular weight
* Ex) The empirical formula of mesitylene is
C3H4. It has a molecular weight of 121 amu.
What is it’s molecular formula
*
* Relationship among the quantities of reactants
and products in a chemical reaction
* Based on dimensional analysis
* Mass to Moles
* Particles to Moles
*
* 2H2 + O2  2H2O
* Each coefficient tells us the number of moles
* Since this tells us the number of moles we can
convert between quantities of different
substances
* Calculate the amount of CO2 produced by the
combustion of 1.00 g of butane
*
* Reactant that is completely consumed in a
chemical reaction
* Determines the amount of product formed
* Quantity of product formed by the limiting
reactant
* Percent Yield: relates the actual yield to the
theoretical yield
*
* What is the mass of 2.50 moles of oxygen gas?
* How many moles are in 1.204 x 1025 molecules
of SO3?
* How many liters of gas do you have in .25
moles?
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