Moles

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Molecular Formula
Molecules
Atoms
Avogadros Number
6.022 x 1023
Moles
Moles
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Chemical Equations
Qualitative Information
Reactants
Products
States of Matter (s) solid (l)
liquid (g) gaseous (aq) aqueous
2 H2 (g) O2 (g) 2 H2O (g)
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Chemical Equation Calculation - I
Atoms (Molecules)
Avogadros Number
6.02 x 1023
Molecules
Reactants
Products
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Chemical Equation Calculation - II
Mass
Atoms (Molecules)
Molecular Weight
Avogadros Number
g/mol
6.02 x 1023
Molecules
Reactants
Products
Moles
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The Haber process for producing ammonia.
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Figure 3.11 Steps in a stoichiometric
calculation.
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Practice Problem 3.79
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Practice Problem 3.80
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Figure 3.14 Limiting reactant analogy using
cheese sandwiches.
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Conceptual Problem 3.13
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Conceptual Problem 3.18
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Practice Problem 3.84
NaClO
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Practice Problem 3.85
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Practice Problem 3.86
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O2? 0.7291 mol SO2
O2 is limiting ? 46.7 g SO2
CS2 ? 0.7879 mol SO2
2.23 g CS2 remaining
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Chapter 4 Chemical Reactions An Introduction
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Suggested Problems for Chapter 4
4.9, 4.12, 4.17, 4.18, 4.23, 4.25, 4.28, 4.29,
4.32, 4.37, 4.39, 4.44, 4.47, 4.55, 4.59, 4.65.
4.73, 4.75, 4.79, 4.95, 4.97, 4.131
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Figure 4.1 Reaction of potassium iodide solution
and lead (II) nitrate solution. Photo courtesy of
James Scherer.
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Figure 4.2 Motion of ions in solution.
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Figure 4.3 Testing the electrical conductivity
of a solution water.Photo courtesy of American
Color.
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Figure 4.3 Testing the electrical conductivity
of a solution sodium chloride.Photo courtesy of
American Color.
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Figure 4.4 Comparing strong and weak
electrolytes HCl. Photo courtesy of American
Color.
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Figure 4.4 Comparing strong and weak
electrolytes NH3. Photo courtesy of American
Color.
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Methanol
Li
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The Role of Water as a Solvent The Solubility
of Ionic Compounds
Electrical conductivity - The flow of electrical
current in a solution is a
measure of the solubility of ionic
compounds or a
measurement of the presence of ions in
solution. Electrolyte - A substance that
conducts a current when dissolved in
water. Soluble ionic compound
dissociate completely and
may conduct a large current, and are called
strong Eeectrolytes.
NaCl(s) H2O(l)
Na(aq) Cl -(aq)
When sodium chloride dissolves into water the
ions become solvated, and are surrounded by water
molecules. These ions are called aqueous and
are free to move through out the solution, and
are conducting electricity, or helping electrons
to move through out the solution
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Fig. 4.2
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The Solubility of Ionic Compounds in Water
The solubility of ionic compounds in water
depends upon the relative strengths of the
electrostatic forces between ions in the ionic
compound and the attractive forces between the
ions and water molecules in the solvent. There
is a tremendous range in the solubility of ionic
compounds in water! The solubility of so called
insoluble compounds may be several orders of
magnitude less than ones that are
called soluble in water, for example
Solubility of NaCl in water at 20oC 365
g/L Solubility of MgCl2 in water at 20oC 542.5
g/L Solubility of AlCl3 in water at 20oC 699
g/L Solubility of PbCl2 in water at 20oC 9.9
g/L Solubility of AgCl in water at 20oC 0.009
g/L Solubility of CuCl in water at 20oC 0.0062
g/L
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Precipitation Reactions Will a Precipitate Form?
If we add a solution containing potassium
chloride to a solution containing ammonium
nitrate, will we get a precipitate?
KCl(aq) NH4NO3 (aq) K(aq)
Cl-(aq) NH4(aq) NO3-(aq)
By exchanging cations and anions we see that we
could have potassium chloride and ammonium
nitrate, or potassium nitrate and
ammonium chloride. In looking at the solubility
table it shows all possible products as soluble,
so there is no net reaction!
KCl(aq) NH4NO3 (aq) No Reaction!
If we mix a solution of sodium sulfate with a
solution of barium nitrate, will we get a
precipitate? From the solubility table it shows
that barium sulfate is insoluble, therefore we
will get a precipitate!
Na2SO4 (aq) Ba(NO3)2 (aq)
BaSO4 (s) 2 NaNO3 (aq)
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