Chlorofluoromethanes (CFMs) are carbon compounds of chlorine and fluorine and are also known as Freons. Examples are Freon-11 (CFCl 3 ) and Freon-12 ( CF 2 Cl 2 ) , which were used as aerosol propellants. Freons have also been used in refrigeration and air-conditioning systems. In 1995 Mario Molina, F. Sherwood Rowland, and Paul Crutzen were awarded the Nobel Prize mainly for demonstrating how these and other CFMs contribute to the “ozone hole” that develops at the end of the Antarctic winter. In other pares of the world, reactions such as those shown below occur in the upper atmosphere where ozone protects the earths inhabitants from harmful ultraviolet radiation. In the stratosphere CFMs absorb high-energy radiation from the sun and split off chlorine atoms that hasten the decomposition of ozone, O 3 . Possible reactions are O 3 ( g ) + Cl ( g ) → O 2 ( g ) + ClO ( g ) Δ H ° = − 126 kJ ClO ( g ) + O ( g ) → Cl ( g ) + O 2 ( g ) Δ H ° = − 268 kJ O 3 ( g ) + O ( g ) → 2 O 2 ( g ) Δ H ° = ? The O atoms in the second equation come from the breaking apart of O 2 molecules caused by ultraviolet radiation from the sun. Use the first two equations to calculate the value of Δ H ° (in kilojoules) for the last equation, the net reaction for the removal of O 3 from the atmosphere.
Chlorofluoromethanes (CFMs) are carbon compounds of chlorine and fluorine and are also known as Freons. Examples are Freon-11 (CFCl 3 ) and Freon-12 ( CF 2 Cl 2 ) , which were used as aerosol propellants. Freons have also been used in refrigeration and air-conditioning systems. In 1995 Mario Molina, F. Sherwood Rowland, and Paul Crutzen were awarded the Nobel Prize mainly for demonstrating how these and other CFMs contribute to the “ozone hole” that develops at the end of the Antarctic winter. In other pares of the world, reactions such as those shown below occur in the upper atmosphere where ozone protects the earths inhabitants from harmful ultraviolet radiation. In the stratosphere CFMs absorb high-energy radiation from the sun and split off chlorine atoms that hasten the decomposition of ozone, O 3 . Possible reactions are O 3 ( g ) + Cl ( g ) → O 2 ( g ) + ClO ( g ) Δ H ° = − 126 kJ ClO ( g ) + O ( g ) → Cl ( g ) + O 2 ( g ) Δ H ° = − 268 kJ O 3 ( g ) + O ( g ) → 2 O 2 ( g ) Δ H ° = ? The O atoms in the second equation come from the breaking apart of O 2 molecules caused by ultraviolet radiation from the sun. Use the first two equations to calculate the value of Δ H ° (in kilojoules) for the last equation, the net reaction for the removal of O 3 from the atmosphere.
Chlorofluoromethanes (CFMs) are carbon compounds of chlorine and fluorine and are also known as Freons. Examples are Freon-11
(CFCl
3
)
and Freon-12
(
CF
2
Cl
2
)
, which were used as aerosol propellants. Freons have also been used in refrigeration and air-conditioning systems. In 1995 Mario Molina, F. Sherwood Rowland, and Paul Crutzen were awarded the Nobel Prize mainly for demonstrating how these and other CFMs contribute to the “ozone hole” that develops at the end of the Antarctic winter. In other pares of the world, reactions such as those shown below occur in the upper atmosphere where ozone protects the earths inhabitants from harmful ultraviolet radiation. In the stratosphere CFMs absorb high-energy radiation from the sun and split off chlorine atoms that hasten the decomposition of ozone,
O
3
. Possible reactions are
O
3
(
g
)
+
Cl
(
g
)
→
O
2
(
g
)
+
ClO
(
g
)
Δ
H
°
=
−
126
kJ
ClO
(
g
)
+
O
(
g
)
→
Cl
(
g
)
+
O
2
(
g
)
Δ
H
°
=
−
268
kJ
O
3
(
g
)
+
O
(
g
)
→
2
O
2
(
g
)
Δ
H
°
=
?
The O atoms in the second equation come from the breaking apart of
O
2
molecules caused by ultraviolet radiation from the sun. Use the first two equations to calculate the value of
Δ
H
°
(in kilojoules) for the last equation, the net reaction for the removal of
O
3
from the atmosphere.
Use the bond enthaplies in this table to determine triangleH for the formafion of hydrazine, N2H4, according to this equation.
Write the law for this reaction and explain how it is determined
SO2CL2 ->SO2 + CL2
Because carbon and silicon are both elements in group 14 on the periodic table,
we expect them to react with other elements in similar ways. To some extent, they do, but in some cases, carbon and silicon compounds that seem to have analogous structures have very different chemical characteristics. For example, carbon tetrachloride, CCl4, is very stable in the presence of water, but silicon tetrachloride, SiCl4, reacts quickly with water. The unbalanced equation for this reaction is
SiCl4 + H2O → Si(OH)4 + HCl
Balance this equation.
Write a conversion factor that could be used to convert between moles of
SiCl4 and moles of H2O.
How many moles of SiCl4 react with 24 moles of water?
Write a conversion factor that could be used to convert between moles of
Si(OH)4 and moles of water.
How many moles of Si(OH)4 form when 4.01 moles of H2O react with an
excess of SiCl4?
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