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Chemistry. Chapter 13 Notes #1. States of Matter. Be able to describe solid, liquid, and gases in terms of: shape volume and particle arrangement!. States of Matter. Solid Definite shape Definite volume Particles are packed together tightly and cannot move past
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Chemistry Chapter 13 Notes #1
States of Matter • Be able to describe solid, liquid, and gases in terms of: • shape • volume • and particle arrangement!
States of Matter • Solid • Definite shape • Definite volume • Particles are packed together tightly and cannot move past each other
States of Matter • Liquid • Definite volume • No definite shape • Particles are close together, but can slide past each other
States of Matter • Gas • No definite shape • No definite volume • Particles are VERY far apart from one another -volume of particles is Very small in comparison To volume of sample
Kinetic Molecular Theory • Explains the properties of gases in terms of the energy, size, and motion of the particles • Size: small particles spread WAY out and there is no significant attraction between the particles • Motion – constant random motion – they move in straight lines until they collide • Energy – determined by mass and velocity • KE = ½ mv2 • Temp is the measure of the average KE in matter
Behavior of Gases • Gases have very low density (not very many particles in any given space) • Gases can be compressed or expanded • How does compression and expansion affect density? • Diffusion – when gases move from areas of high concentration to area of low concentration (due to random motion of particles) • Effusion – diffusion thru a small hole into a vacuum
Pressure • Pressure = Force per unit area • Outside on a snowy day • High heels v. tennis shoes v. snow shoes • Gases exert pressure on the walls of their container when they collide with the container • Barometer = instrument used to measure atmospheric pressure (commonly Hg) • Increase in pressure = mercury rises • Decrease – it drops • Can be affected by altitude
Units of Pressure • kPa, psi, mm Hg, torr, atm, etc… • Pascal (Pa) is the SI unit
Pressure Conversions • 0.5 atm to kPa • 300 kPa to atm • 3.2 atm to psi • 99 psi to atm
Dalton’s Law of Partial Pressures • Total pressure of a mixture of gases is equal to the sum of the pressures of all the gases in the mixture
Example problems • Find the total pressure of a mixture of gases that have partial pressures of 5.0kPa, 4.56 kPa, 3.02kPa, and 1.2 kPa. • What is the partial pressure of H gas in a mixture of H and He if the total pressure is 600 mm Hg and the partial pressure of He is 439 mm Hg. • Find the total pressure of the following mixture of gases (in atm) if the partial pressures are as follows: 6.2 atm, 3.1 atm, and 506 kPa.