Lesson 1: GAS 😮‍💨🌬️

• Gases have

  • volume
  • mass
  • temperature.
  • exert pressure
• Kinetic Molecular Theory – states that all matter are made up of atoms and molecules constantly moving, they hold kinetic energy and move around in random directions
• Particles in ideal gas…

  • have no volume
  • don’t attract or repel each other
  • have elastic collisions
  • are in constant, random, straight-line motion
  • have an average KE directly (∝) related to Kelvin temperature
• Particles in a real gas..

  • have their own volume
  • attract each other

  Note: Real gases can act like ideal gases in ↓ LOW pressures, ↑ HIGH temperatures, and NONPOLAR atoms and molecules. 
• Characteristics of Gases

  1. They expand to FILL CONTAINERS. Random motion and no attraction.
  2. They are FLUIDS. Like liquids. 
  3. Have VERY LOW density. No volume = lots of empty space. 
  4. Can be COMPRESSED. 
  5. Undergo DIFFUSION & EFFUSION

  Diffusion - spreading of gas molecules

  Effusion - passing of molecules through a tiny opening

  Note: Diffusion is smelling a perfume scent. Effusion is spraying perfume. 
• Temperature - K (Kelvin) is the standard

  K = °C + 273

  °C = (5/9) (F - 32)
• Pressure

  1 atm (atmospheric pressure) is the standard
• 101.325 kPa (kilopascal)

  1 atm

  760 mm Hg

  760 torr
• The smaller the area, the greater the force.
• • A barometer is used to measure atmospheric pressure. 

  1. Mercury barometer – have liquid
  2. Aneroid Barometer
• Mass

  • The mass of gas in a one-mole sample = molar mass of gas
  • Ex. If the molar mass of gas X was 40 g/mol, what is its mass? 40 g
• Volume

  A) 1cm3

  B) 1dm3

  C) 1000l

  
• Boyle's Law (PV = k)

  • PRESSURE and VOLUME are INVERSE at constant mass & temp$P_1V_1 =$$P_2V_2$
• Boyle's Law

  
• Examples of Boyle's Law Applications

  1. Breathing – diaphragm move downward (volume of lungs increase), so that air rushes in (pressure inside the lungs lessen)
  2. Syringe
  3. Bicycle pump
• Charles’ Law (v/t = k)

  VOLUME and TEMPERATURE are DIRECT at constant mass & pressure

  $V_1/T_1 =$$V_2/T_2$
• EXAMPLES OF CHARLES' LAW:

  1. Balloons in hot and cold temps.
  2. Hot air balloon
  3. Yeast in bread
• Gay Lussac’s Law (p/t = k)

  PRESSURE and TEMP are DIRECT at constant mass & volume

  $P_1/T_1 =$$P_2/T_2$
• EXAMPLES OF GAY LUSSAC'S LAW:

  1. Pressure cooker
  2. Firing gun (gunpowder)
  3. Car tires
• Charles' Law

  
• Gay Lussac's Law

  
• Combined Gas Law

  
• STP (Standard Temperature and Pressure)


  Temp - 273 K

  Pressure - 1 atm
• Combined Gas Law (ᵖᵛ⁄ₜ = k)

  PRESSURE and VOLUME are INVERSE, however they are both DIRECT proportional to the TEMPERATURE. At constant temperature

  A) P2V2

  B) T2

  
• Avogadro’s Principle (ᵛ⁄ₙ = k)

  • “EQUAL VOLUME = EQUAL NO. MOLES"
  • VOLUME and N are DIRECT
  • At constant temperature & pressure
  • True for ANY gas

  A) V2

  B) N2

  
• Avogadro's Principle

  
• Ideal Gas Law

  • Avogadro stated that, "Equal volumes of all gases kept at the same pressure and temperature, contain the same number of molecules." (V/n = k)
  • The ideal gas equation is useful in illustrating the relationship among the pressure, volume, temperature, and number of moles of a gas.
• The universal gas constant (R) is 0.0821 L. atm mol. K
• Ideal Gas Law

  A) Pressure

  B) Number of Moles

  C) Temperature

  D) Gas constant

  E) Volume