Science- 4th Quarter

• This is used to describe the nature and behavior of gasses as it is always in constant motion

  Kinetic Molecular Theory
• What do we examine in the Kinetic Molecular Theory?

  Macroscopic Properties of a Gas and Microscopic Components, such as atoms
• When we say Kinetic, what does it mean?

  Movement/ Motion
• Macroscopic properties such as?

  Pressure and Temperature
• What are the 5 postulates of the Kinetic Molecular Theory?

  1. Gas are made up of particles that has no defined volume but has a defined mass
  2. Gas particles undergo no intermolecular attractions or repulsions
  3. Gas particles are in continuous, random motion
  4. Collision between gas particles are elastic
  5. The average kinetic energy is same for all gases at a given temperature
• What is the total energy of gas from?

  the summation of the kinetic energy of gases
• Air is a mixture of different gases, mainly Nitrogen 78%, Oxygen 21%, and other gases 1%
• Natural Gas comes from the ground, and burns easily.
• Where is natural gas used?

  Heating
• What chemical element is natural gas?

  CH4
• Oxygen is the byproduct of photosynthesis in plants
• CO2 is needed by plants to make their own food.
• Where is carbon dioxide used?

  In soft drinks.
• What is the most abundant gas?

  Nitrogen
• Nitrogen is the main gas in the air, used in fertilizer and explosives.
• Helium is composed of very light gas, which helps the balloons to float
• Argon is used in electric light bulbs
• PROPERTIES OF GASES

  1. Gases can completely fill up a container
  2. Gases diffuse very rapidly
  3. Compressibility and expandability depending on the pressure applied
  4. Less dense than the others
  5. Gases have mass
  6. Exerts uniform pressure in all directions on the walls of container
• What are the quantitative properties of gases?

  • Volume
  • Pressure
  • Temperature
  • Amount of number of moles
• Molecules of gases occupy space. It may be proven when the gas fills up its container. Volume is one of the measurable properties of gas, is denoted by the symbol V.

  *1 cm3 (centimeter cubed) =1 mL (milliliter)

  *1000 cm3 = 1 L = 1 dm3
• When you inflate a balloon, it expands because molecules of gases strike the walls of the balloon causing the pressure on it. Pressure of the gas is the force exerted by the gas over a unit of area.
• In the world, the measure of pressure is Pascal (Pa)

  In the Philippines, the measure of pressure is Atmospheric Measure (atm)
• 1atm

  =760mmHg

  =760torr

  =1.01325 bar

  =101.325kPa
• The temperature of gas depends on the kinetic energy of gas. Gas expands when heated.
• K= °C + 273.15

  °F= 9/5 (°C)+ 32

  °C=5/9 (°F -32)
• The absolute zero in K is 0, while in °C is -273.15, while in °F is -459.67.

  The freezing point of water in K is 273.15, while in °C is 0, while in °F is 32.

  The boiling point of water in K is 373, while in °C is 100, while in °F is 212.
• The mass of gas is related to the number of moles of gas, expressed in

  kg or g
• The formula for the amount or number of moles is:

  number of moles is equal to mass in grams over molar mass of the gas

  or n=m/M