LBS_172_Exam 1 - LBS 172 Exam 1 Review Chapter 12- Gases I....

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
LBS 172 Exam 1 Review Chapter 12- Gases I. What is a gas? a. Properties i. Non-definite volume, fills container, can flow, spread out, can be compressed b. Air is a gas composed of many gases i. Relatively stable gases are: 1. N 2 – 78.1% O 2 – 20.9% Ar – 0.9% He – 0.0005% H 2 – 0.00005% Kr Ne ii. Gases whose composition varies are: 1. CO 2 – 0.035% H 2 O – 0-4% CO CH 4 – 0.0002% O 3 – 0.000004% II. What kinds of substances are gases? a. Nonmetals, small molecules i. Binary molecules: 1. H 2 , N 2 , O 2 , F 2 , Cl 2 , O 3 (ozone) ii. Noble gases: 1. He, Ne, Ar, Kr, Xe, Rn b. Other gases i. CO 2 – greenhouse gas (22x better than CH 4 but decays slower) ii. CH 4 – greenhouse gas (cow burps release 400-500 L/day) iii. NH 3 iv. NO – acid rain precursor v. NO 2 – smog, acid rain precursor vi. N 2 O – nitrous oxide is laughing gas used for dental work vii. H 2 S – smell of rotten eggs viii. HCN – hydrocyanic acid is a deadly poison that tastes like almonds ix. SO 2 – acid rain precursor c. Any aroma is due to gaseous molecules III. Microscopic characteristics of gases a. Particles are randomly moving b. Particles have elastic collisions i. They bounce off of each other with no net loss of energy c. Particles exert pressure by bouncing off of container wall IV. Results in macroscopic world
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Simple relationship between moles, pressure (P), volume (V), and temperature (T) b. Gases are compressible c. Gases have a much lower density than solids and liquids d. Gases will mix evenly and completely when put in the same container i. There is no such thing as immiscible gases V. Pressure a. Gases exert pressure by bouncing off of the walls of a container i. The more collisions, the more pressure ii. The higher the speed of the collisions, the more pressure b. Units of pressure i. Atmospheric pressure (at sea level) is 1.01x10 5 Pa = 101 kPa = 1 atm (atmosphere) c. How is pressure measured? i. The barometer was invented by Torricelli in the 1700s 1. It is a glass tube inverted in a dish of Hg and the atmospheric pressure keeps the Hg in the tube. Hg is used because it is the densest liquid at room temperature (1.0 atm) ii. 1.0 atm = 760 mm Hg = 29.92 in. Hg = 760 torr = 101 kPa = 1.0x10 5 Pa VI. Relationships between physical properties of gases a. Relationship between pressure (P) and volume (V) i. Boyle’s Law was discovered in 1650 1. It states that V is inversely proportional to P a. P increases, V decreases 2. V α 1/P Æ V = k (1/P) Æ PV = k 3. P 1 V 1 = k = P 2 V 2 Æ P 1 V 1 = P 2 V 2 b. Relationship between volume (V) and number of moles (n) i. Avogadro’s Law 1. It states that number of moles is directly proportional to volume under the conditions of constant pressure and temperature a. V increases, n increases 2. V α n Æ V = kn Æ V/n = k 3. V 1 /n 1 = k = V 2 /n 2 Æ V 1 /n 1 = V 2 /n 2 a. Note that this law is not dependent on the type of
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

LBS_172_Exam 1 - LBS 172 Exam 1 Review Chapter 12- Gases I....

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online