bell work
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Bell Work. Find the ΔH for the reaction below, given the following reactions and subsequent ΔH values: 2 SO 2 (g) + 2 P(s) + 5 Cl 2 (g ) 2 SOCl 2 (l) + 2 POCl 3 (l) - PowerPoint PPT PresentationTRANSCRIPT
Bell Work
Find the ΔH for the reaction below, given the following reactions and subsequent ΔH values:
2 SO2(g) + 2 P(s) + 5 Cl2(g) 2 SOCl2(l) + 2 POCl3(l)
SOCl2(l) + H2O(l) SO2(g) + 2 HCl(g)ΔHo/kJ = +10.3
PCl3(l) + 1/2 O2(g) POCl3(l)ΔHo/kJ = -325.7
P(s) + 3/2 Cl2(g) PCl3(l) ΔHo/kJ = -306.7
4 HCl(g) + O2(g) 2 Cl2(g) + 2 H2O(l) ΔHo/kJ = -202.6
What is the change in temperature, if 3450J of heat are added to a 23.4 gram sample of Fe. (Specific heat of iron is 0.444 J/g0C
GasesChapter 13
Properties
Uniformly fills a container
Easy to compress
Mixes completely with other gases
Exerts pressure on surroundings
Atmospheric pressure results from the mass of the air being pulled toward the center of the earth by gravity---weight of the air.
Units of pressure
mmHg (millimeters of mercury)
Torr Torr and mmHg can be used interchangeably
Atm (standard atmosphere)
Pascal
Kinetic-Molecular theory
Gases can be compressed easily, but liquids and solids cannot be compressed because particles are already close together
The intermolecular forces between gases are weak.
Gas particles move until a collision alters their course
Energy added into the system increases the kinetic energy of the particles, which translates to an increase in temperature of the gas.
Relationship between pressure and volume
Boyle’s law- pressure times volume equals a constant
P1V1=P2V2
Example of Boyle’s Law
A container holds 500. mL of CO2 at 20.° C and 742 torr. What will be the volume of the CO2 if the pressure is increased to 795 torr?
V1=500mL
P1=742 torr
V2= x
P2=795 torr
(500mL)(742Torr)=(x)(795Torr)
X=470mL
Practice Problem
A gas tank holds 2785 L of propane, C3H8, at 830. mm Hg. What is the volume of the propane at standard pressure, 760mmHg?
V1P1 = V2P2
(2785L)(830mmHg)=(x)(760mmHg)
3042L
Relationship between volume and temperature
Charles’s Law-gas volume is directly proportional to the temperature
V1 = V2
T1 T2
Temperature is in Kelvin (+273)
Example of Charles’s Law
A container holds 50.0 mL of nitrogen at 25° C and a pressure of 736 mm Hg. What will its volume be, if the temperature increases by 35° C?
V1 = V2 T1 T2
50mL = x 298K 333K
x= 56mL
Practice problem
A sample of helium has a volume of 521 dm3 at a pressure of 75 cm Hg and a temperature of 18° C. When the temperature is increased to 23° C, what is the volume of the helium?
V1 = V2 T1 T2
521dm3 = x 291K 296K
=530dm3
Combined gas Law
P1V1 = P2V2 T1 T2
The combined gas law is a mix between Charles’s, Boyle’s, and Gay-Lussac’s Laws
Example
A sample of argon has a volume of 5.0 dm3 and the pressure is 0.92 atm. If the final temperature is 30.° C, the final volume is 5.7 L, and the final pressure is 800. mm Hg, what was the initial temperature of the argon?
P1V1 = P2V2 T1 T2
(5.0dm3)(0.92atm) = (5.7L)(1.05atm)x 303K
=233K
Practice problem
A sample of sulfur dioxide occupies a volume of 652 mL at 40.° C and 720 mm Hg. What volume will the sulfur dioxide occupy at STP?
P1V1 = P2V2 T1 T2
(652mL)(720mmHg) = (x)(760mmHg)313K 273K
539mL
Avogadro’s Law
States that the volume of gas is proportional to the number of gas particles at constant temperature and pressure.
I.E. A volume occupied by one mole of gas is 22.4L when the temperature of the gas is at 0oC and its pressure is at 1atm.
These conditions are referred to as standard temperature and pressure (STP)
STP conditionsstandards listed below
22.4 Liters
1 atm=760mmHg or Torr
273 K
Example of STP
Calculate the number of moles of nitrogen gas produced and grams of sodium azide consumed if 115L of N2 results from a sodium azide explosion.
115L x 1mol 22.4L
=5.13 moles
Ideal gas Law
PV=nRT
P-pressure(atm)
V-volume(L)
n-number of moles (mol)
R-constant (0.0821L*atm/mol *K)
T-temperature (Kelvin)
Example
A reaction yields 3.75 L of nitrogen monoxide. The volume is measured at 19°C and at a pressure of 1.10 atm. What mass of NO was produced by the reaction?
PV=nRT
(1.10atm)(3.75L) =x(0.0821L*atm/mol*K)(292K)
0.17moles
0.17mol x 30g/mol
5.1 g
Practice problem
What is the pressure inside a tank that has a volume of 1.20 x 103 L and contains 12.0 kg of HCl gas at a temperature of 18°C?
PV=nRT
(x)(1.20x103L)=(329mol)(0.0821L*atm/mol*K)(291K)
6.6atm