TEST

• 3 States of Matter


  • Solid
  • Liquid
  • Gas
• Properties of Gases


  • Most gases exist as molecules (except for the inert gases as individual atoms)
  • The molecules of gases are randomly distributed and far apart
  • Gases can be easily compressed
  • The volume or the space occupied by the molecules themselves is negligible as compared to the volume of the container, so the volume of the container can be taken as the volume of the gas
  • Gases have low densities than solids and liquids
  • The attractive forces between molecules (intermolecular force) are negligible
  • Most substances that are gaseous at normal conditions have low molecular mass
• Measurable Properties of Gases


  • Pressure
  • Volume
  • Temperature
  • Amount of gas
  • Density

  
• Pressure


  Force exerted by gas molecules as they collide with each other
• Volume


  Space occupied by the gas particles at STP conditions
• Temperature


  Measure of the average KE (kinetic energy) of the molecules

  
• Amount of gas


  Measured in mol
• Density


  Mass of gas occupying a certain volume at specified T and P
• Conversion of Temperature


  1. 0C to K: 0C + 273

  2. K to 0C: K - 273
• At STP (Standard Temperature and Pressure) or SC (Standard Conditions): 1 atm (atmosphere) = 760 torr = 760mmHg, T = 00 C = 273 K

  
• At absolute 0 (0 K), molecules stop moving entirely, the gas is as cold as anything it can get
• Postulate


  Claim, suggestion, assume
• Kinetic Molecular Theory


  Describes the behavior of IDEAL GASES at the particle level
• Postulates of Kinetic Molecular Theory


  • The particles in a gas are in CONSTANT, RANDOM motion
  • The combined volume of the particles is negligible
  • The particles exert NO FORCES on one another
  • Any collision between the particles is completely elastic (NO TRANSFER OF ENERGY)
  • The average KE of the particle is proportional to the temperature in K
• Boyle's Law


  At a given temperature, the VOLUME occupied by a gas is INVERSELY PROPORTIONAL to the PRESSURE

  
• Boyle's Law


  P1V1 = P2V2
• High Pressure


  Low Volume
• Low Pressure


  High Volume
• Boyle's Law Sample Problems


  • Solving for final volume given initial volume, pressure, and final pressure
  • Solving for final volume given initial volume, pressure, and final pressure
• Practical Applications of Boyle's Law


  • Inflating tires
  • Breathing (Respiration)
  • Soda bottle
  • Working of a syringe
• Charles' Law


  At a given Pressure, the VOLUME occupied by a gas is DIRECTLY PROPORTIONAL to the absolute TEMPERATURE of the gas

  
• Charles' Law


  V2 = (V1T2)/T1
• High Temperature


  High Volume
• Low Temperature


  Low Volume
• Charles' Law Sample Problems


  • Solving for final volume given initial volume, temperature, and final temperature
  • Solving for final temperature given initial volume, final volume, and initial temperature
• 0 cm3
• T2 = 42,450 K
• T2 = 169.8 K
• An inflated balloon with a volume of 0.75 L at 300C was placed inside the freezer where the temperature is -100C. Find out what will happen to the volume of the balloon if the pressure remains constant. Support your answer with computation.
• A gas occupies 900.0 mL at a temperature of 27.0 °C. What is the volume at 132.0 °C?

  
• When the volume of a gas is changed from ___ mL to 852 mL, the temperature will change from 315 °C to 452 °C. What is the starting volume?

  
• A balloon filled with helium gas occupies a volume of 2.5 liters at a temperature of 20°C. If the balloon is heated to 50°C, what will be its new volume if the pressure remains constant?
• A sample of nitrogen gas has a volume of 150 mL at 300 K. If the temperature is increased to 450 K, what will be the volume of the gas, assuming the pressure is unchanged?

  
• Hot Air Balloon


  • The air inside the balloon, when heated causes the air to expand; thus, becomes lighter and so it rises.
• Inflated balloon


  • Shrinks when placed inside the refrigerator.
• Bicycle tires


  • Become flat during cold weather because the air inside the bicycle tires shrink.
• Gay-Lussac's Law


  At constant volume, the PRESSURE of a fixed mass of gas is DIRECTLY PROPORTIONAL to the absolute TEMPERATURE.

  
• The pressure of a nitrogen gas inside a rigid tank is 1.5 atm at 300C. What will be the resulting pressure if the tank is cooled to 00C?
• A certain light bulb containing argon has a pressure of 1.20 atm at 18°C. If it will be heated to 85°C at constant volume, what will be the resulting pressure? Is it enough to cause sudden breakage of the bulb?
• A 30 L sample of Nitrogen inside a rigid, metal container at 200C is placed inside an oven whose temperature is 500C. The pressure inside the container at 200C was 3 atm. What is the pressure of the nitrogen after its temperature is increased to 500C?