chem 121 chapter 7 winter 2014 1. kinetic molecular theory of matter explains matter in various...
TRANSCRIPT
CHEM 121
Chapter 7
Winter 2014
1
Kinetic Molecular Theory of Matter
Explains matter in various states
1. 2.
3.
4. 5.
2
States of Matter
Matter:
Physical states:
•
•
•
3
Properties of Matter:
•
•
•
•
Solids• Strong attractive forces ( )•
Properties:
• _________________ density
• _________________ compressibility
• _________________ shape
• _________________ thermal expansion
4
Liquids• Medium forces ( )•
Properties:
• _________________ density
• _________________ compressibility
• _________________ shape
• _________________ thermal expansion
5
Gases
• No attractive forces• High kinetic E:
Properties:
• _________________ density
• _________________ compressibility
• _________________ shape
• _________________ thermal expansion6
Measuring Pressure
Pressure (P)
http://encarta.msn.com/media_461532488_761573986_1_1/mercury_barometer.html
Barometer:
7
Units of Pressure
• pascal• •
• atmosphere•
• Millimeter of mercury• •
• psi, pounds per square inch (engineering)
mmHg 760 atm 1
8
Gas Laws
9
4 Variables:
P:
T:
V:
n:
•
Boyle’s Law
volume occupied by a gas is __________ related to its pressure
10
A sample of gas has a volume of 100.0 mL at 1.0 atm. If we increase the pressure to 2.0 atm, what is the new volume of the gas (T is constant)?
11
3-minute practice
Charles’s Lawvolume of a gas is __________ related to its temperature
(K)
12
A sample of gas has a volume of 100.0 mL at 27 ˚C. If we heat the gas to 54 ˚C (keeping P constant), what is the new volume of the gas?
13
3-minute practice
Gay-Lussac’s Law
At constant volume, pressure is __________ related to temperature
Combined Gas Law:
14
Avogadro’s LawThe volume occupied by a gas is __________
proportional to the amount (mol) of gas(fixed T & P)
At fixed T & P:equal volumes of any ideal gas have…• •
15
Gas Behavior at STP• STP:
•
•
• Standard Molar Volume
16
What is the volume (mL) of 0.10 g of helium gas at STP?
17
3-minute practice
Ideal Gas LawCombine:
– Boyle’s Law
– Charles’s Law
– Avogadro’s Law
Solve at STP…
18
A tank filled with methane at 23 ˚C and 0.991 atm is fitted with a safety valve that opens if internal pressure exceeds 1.00 x 103 torr. When the tank is placed in boiling water at exactly 100. ˚C, will the safety valve open?
Initial:T =P =n =V =
Final:T =P =n =V =
19
A sample of gas occupies 105 mL at 0.903 atm. If temperature remains constant, what is the volume (in L) at 26.4 kPa?
Initial:P =V =n =
T =
Final:P =V =n =T =
20
Each gas in a mixture acts like it is the only gas present
Dalton’s Law of Partial Pressures:
Mixtures of Gases
Example: When water vapor added to pure air….
Each gas exerts __________________________________
21
Graham’s Law
• Effusion: gas leak through hole
• Diffusion: spontaneous mixing of gases
22
B
A
rate
rate
A massmolecular
B massmolecular
Which will deflate more quickly:
a balloon filled with helium or nitrogen?
23
3-minute practice
Changes of State
24
Intermolecular Forces:
• dipole-dipole• polar molecules
acting like magnets
• if between H andN, O, or F
_______________
O
Intermolecular Forces
25
H
H OH
H
OH
H
• London Dispersion forces• •
Vapor PressureAs a liquid evaporates:
• • • But if closed container…
26
Vapor Pressure:
Boiling• As you increase T, vapor pressure _____________• If vapor pressure reaches atmospheric pressure…
27
Sublimation and Melting
Solids have vapor pressures too!– Typically low or high?
Sublimation:
Melting:
Decomposition:
28
Heating and Cooling Curves
• Plateaus: • Slopes:
29
Specific Heat (SH)Amount of heat to raise the T of ___ of a substance by
____
30
How much energy is needed to raise the temperature of 20.0 g of iron by 14.5 °C?
Changes of State Equations• Heat of Fusion:
•
• Heat of fusion for water = 80 cal / g
• Heat of Vaporization:
•
• Heat of vaporization for water = 540 cal / g
31
Solid State
32
