4thQ-Week-1-Boyles-law

Motivational Activity

  • Activity 1: Pics-to-Word

    • Guess the specific word via a series of pictures and a short definition as a clue.

Gas Properties

Temperature of a Gas

  • Temperature is a measure of hotness or coldness of an object.

  • Proportional to the average kinetic energy of gas molecules.

  • Measured in Celsius or Kelvin; Kelvin is the absolute scale.

Pressure in Gases

Definition of Pressure

  • Pressure: The force exerted per unit area.

  • Measured in atmosphere, torr, psi, cmHg, mmHg.

  • Confined gas pressure results from collisions of gas molecules with container walls.

Volume of Gases

Definition of Volume

  • Volume: The amount of 3-dimensional space occupied by gas.

  • Gases occupy all available space in a container due to weak intermolecular forces.

  • Common units for volume: liter (L), milliliter (mL).

Key Units in Boyle's Law

Pressure Units

  • SI Units: Pascal (Pa)

  • Metric Units: atmosphere (atm), mm Hg, cm Hg.

  • English Units: torr, psi.

Volume Units

  • SI Units: cubic meter (m³), cubic decimeter (dm³), cubic centimeter (cm³).

  • Metric Units: liter (L), milliliter (mL).

Important Equivalents

  • Volume: 1 mL = 1 cm³, 1 L = 1 dm³, 1 m³ = 1000 L.

  • Pressure: 1 atm = 760 mm Hg = 76 cm Hg = 760 torr = 101325 Pa = 14.6956 psi.

  • Temperature: 0°C = 273.15 K, 0°C = 32°F.

Properties of Gases

Behavior of Gases

  • Highly compressible; applying pressure decreases volume.

  • Expand when heated—particles move faster and farther apart.

  • Flow easily and are miscible with each other.

  • Lower densities than solids and liquids due to far apart particles.

Kinetic Molecular Theory (KMT)

Overview

  • Explains gas behavior using particles and kinetic energy.

  • Composed of tiny atoms/molecules; most volume is empty space.

  • Particles move randomly and collide elastically in a container.

Kinetic Energy Relation

  • Average kinetic energy relates to absolute temperature (Kelvin).

  • Kinetic energy equation: KE = ½ mv², where m = mass and v = velocity.

  • Higher mass or velocity increases kinetic energy, and temperature rise increases gas speed.

Boyle's Law

Relationship of Pressure and Volume

  • Pressure is inversely proportional to volume for a fixed amount of gas at constant temperature.

  • Formula: P₁ x V₁ = P₂ x V₂.

  • As pressure increases, volume decreases.

Problem Solving with Boyle's Law

Example Problems

  1. Gas in a Tank:

    • Initial Pressure (P₁) = 2 atm, Initial Volume (V₁) = 3 L.

    • Final Volume (V₂) = 6 L, find P₂.

  2. Gas Compression:

    • Initial Conditions: 10 mL at 20 Pa, Pressure changes to 5 Pa.

  3. Diver's Tank:

    • Initial Volume = 5 L, Final Pressure = 8 atm, Pressure changes to 16 atm.

Applications

  • Human Lungs:

    • Lung volume changes during inhaling (increased volume, decreased pressure) and exhaling (decreased volume, increased pressure).

  • Syringe Mechanics:

    • Plunger down = decreased volume, increased pressure.

  • Bicycle Pumps:

    • Pump handle down compresses air (increased pressure).

  • Scuba Diving:

    • Lung volume decreases underwater due to higher pressure, increases ascension.

Conclusion

  • Understanding gases and their behavior through concepts such as pressure, volume, and kinetic energy provides insights into various practical applications.