Download I. Structure of Matter

Objectives
• I. Structure of Matter
• C. Nuclear chemistry: nuclear equations,
half-lives, and radioactivity; chemical
Objectives (cont.)
• III. Reactions
• A. Reaction types-Synthesis,decomposition
and combustion
• B. Stoichiometry
• 2. Balancing of equations
• 3. Mass and volume relations with
emphasis on the mole concept, including
• empirical formulas and limiting reactants
Use 52c
• When 15 g of gold(III) sulfide reacts with
800 mL of hydrogen gas at 4 atm and 100
degrees C, 10 g of pure gold is recovered.
• What is the theoretical yield of gold?
• What is the percent yield of gold?
Use equation #52e
• How many L of sulfur tetrafluoride will be
collected at 25 degrees C from 25 mL of
liguid HF (d = 1.34 g/mL)?
Use equation 51b
• Xenon tetrafluoride gas is charged into a
5L flask containing water at 27 degree C
and 800 torr. What is the pressure in the
container when the reaction has gone to
completion at the same temperature?
Use equation 51e
• When 35 g of NaCl is dissolved in excess
water, sulfur dioxide gas is bubbled into
the mixture reacting all of the salt. What
would be the M of the HCl formed if the
final solution had a volume of 250 mL?
Synthesis Reactions
• A metal combines with a nonmetal to form
a binary salt
• Example:
lithium metal is dropped in nitrogen gas
• Metallic oxides and water form bases
(metallic hydroxides)
• Example:
solid sodium oxide added to water
solid magnesium oxide added to water
• Nonmetallic oxides and water form acids.
(the nonmetal retains its oxidation number)
• Example:
Carbon dioxide is bubbled into water
dinitrogen pentoxide is bubbled into water
• Metallic oxides and nonmetallic oxides
form salts
• Example:
solid sodium oxide is added to carbon dioxide
solid calcium oxide is added to sulfur trioxide
Decomposition Reactions
• Metallic carbonates decompose into
metallic oxide and carbon dioxide
• Example:
magnesium carbonate is heated
• Metallic chlorates decompose into metallic
chlorides and oxygen
• Example:
magnesium chlorate is heated
• Binary compounds break down into their
elements
• Example:
• Molten sodium chloride is electrolyzed
• Sulfurous acid decomposes into sulfur
dioxide and water
• Carbonic acid decomposes into carbon
dioxide and water
• Ammonium carbonate decomposes into
ammonia, carbon dioxide and water
• Ammonium hydroxide decomposes into
ammonia and water (ammonia water)
• Hydrogen peroxide decomposes into water
and oxygen
Combustion
• aCxHy + bO2  cCO2 + dH2O
• If x/2 is even, then x is coefficient(c) of CO2
• If x/2 is odd, then 2x is coefficient(c) of CO2 and 2
is coefficient(a) of the hydrocarbon
• Balance water and oxygen
– d = ay/2
– b = c + d/2
• CxHyOz + O2  CO2 + H2O
• Balance by inspection
• Other organic compound combustion
problems will tell you other products
Stoichiometry
• See the equation #53 on p. 72
• How many grams of fluorine are needed to
react with 15.2 g cyanogen gas?
• How many grams of fluorine are needed to
make 235.6 g of NF3?
Limiting Reactions
• Using the same equation
• How many grams of carbon tetrafluoride
are made when 12.5 g cyanogen reacts
with 3.4 g of fluorine?
• DO #67a on p. 73
Percent Yield
• 67B
• 67C
Gaseous Stoichiometry
• Density = mass / volume may be a given
• At STP, 1 mol = 22.4 L for ANY gas
• At all other conditions, PV = nRT
–
–
–
–
The units for P must match the R value
All temperatures must be in Kelvin
The volume must be in Liters (dm3)
The number of moles is n
Gas Stoichiometry
• Moles of solids is mass/formula mass
• Moles of gas is PV/(RT)
Gas Stoichiometry
• For the equation:
• 4PH3 (g) + 8O2 (g)  P4O10 (s) + 6H2O (g)
• How many grams of P4O10 is made when
2.4 L of phosphine is burned in air at 22oC
and 137 kPa?
4PH3 (g) + 8O2 (g)  P4O10 (s) + 6H2O (g)
• How many L of water at 95oC and 1.2 atm
is made when 14.6 g of tetraphosphorus
decoxide is made?
• How many L of oxygen is needed to burn
2.9 L of phosphine if measured at the same
conditions?
4PH3 (g) + 8O2 (g)  P4O10 (s) + 6H2O (g)
• How many L of oxygen at STP will be
needed to generate 89.1 g of P4O10?
NUCLEAR
• Isotopes are versions of an element with
different number of neutrons
• Most elements exist as a mixture of their
isotopes
• The atomic mass on the periodic table is a
weighted average of all the isotopes
Isotope notation
• Zinc naturally exists as 5 isotopes
• Zn-64, Zn-66, Zn-67, Zn-68, Zn-70
• All zinc has 30 protons; the number
represents the mass, hence, a difference in
the # of neutrons
• Another notation is 6430Zn
Nuclear Reactions
• The sum of the masses are conserved
• The sum of the charges are conserved
•
a X
b
+ cdY  a+cb+dZ
• The superscripts are masses.
• The subscripts are the atomic numbers/hence, the
identity of the element.
Special Nuclear Particles
•
•
•
•
•
•
•
Alpha particle: 42He
Beta particle: 0-1e
Positron: 0+1e
Neutron: 10n
K-capture is an electron (beta particle)
Deuterium: 21H
Tritium: 31H
Nuclear Reactions
• The loss of a positron by Y-85
• The fission of Pu-239 to give Sn-130, two
neutrons and another nucleus
Nuclear Reactions
• The alpha emission forming Pa-233
• The fusion of two C-12 nuclei to give Na23 and another particle
Nuclear Reactions
• Bombard U-238 with a nucleus to produce
Fm-249 and five neutrons
• Bombard Al-27 with deuterium to produce
and alpha particle and another nucleus
Nuclear Reactions
•
235 U
92
+ 10n  13754_____+210n + ______
• Rubidium-81 undergoes K-capture
Formula from Analysis
• 37A on p. 71
Combustion Analysis
• When any hydrocarbon burns, the same
products are always made: CO2 + H2O
• All of the carbon from the hydrocarbon
turns into carbon dioxide.
• All of the hydrogen in the hydrocarbon
turns into water.
• The amount of oxygen is from 2 sources.
Combustion Analysis
• P. 71 #39
Combustion Analysis
• If the hydrocarbon has other elements in it,
the analysis of the other products will be
given to you.
• #41 p. 72
• #43 p. 72
MM determination
• An unknown gas collected in a 1-liter flask
at 25oC and 191 kPa has a mass of 2.63 g.
What is the molar mass of the gas?
• What is the molar mass of a solute if 50.0 g
dissolved into one-liter of solution at 15oC
has an osmotic pressure of 3.45 atm?
MM determination
• When 15.0 g of an unknown nonelectrolyte
is dissolved in 250 mL of acetic acid, the
freezing point is 12.89oC. What is the
molar mass of the solute?
• P. 278 #39,41,43
Molecular Mass Determinations
Using Colligative Properties
• At a certain temperature, the vapor pressure of benzene is
0.930 atm. A solution prepared by dissolving 10.0 g of a
molecular, nonvolatile solute in 78.11 g benzene at that
temperature has a vapor pressure of 0.900 atm.
Determine the MM of the solute.
• A 0.350 g sample of a large biomolecule was dissolved in
15.0 g chloroform and the freezing point depression was
0.24oC. Determine the MM of the molecule if Kf
chloroform is 4.70.
• An aqueous solution of 10.0 g catalase dissolved to make
1L of solution at 27oC has an osmotic pressure of 0.745
torr. Determine the MM of catalase (an enzyme found in
liver).