• Pressure (P) - the force exerted on a surface divided by the area of the surface

Properties of Pressure

• Pressure increases as more gas is added
  • Conclusion - Pressure (P) is directly proportional to moles of gas (n)
• Pressure is measured in units that describe force exerted by the gas divided by area over which the gas is distributed.
  • e.g. lb/in²
  • Conclusion  -        

• Pressure due to a gas is the same in all directions whereas pressure due to weight is directional

			Evangelista Torricelli
		Barometer - apparatus used to measure pressure; derived from the Greek "baros" meaning "weight" Created by Evangelista Torricelli in 1646 Inverted a tube filled with mercury into a dish until the force of the Hg inside the tube balanced the force of the atmosphere on the surface of the liquid outside the tube

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