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GASES. 5 Assumptions of Kinetic Theory. Gases- large numbers of tiny particles that are far apart for their size They occupy a volume 100 times greater than gases or liquids
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5 Assumptions of Kinetic Theory • Gases- large numbers of tiny particles that are far apart for their size They occupy a volume 100 times greater than gases or liquids Most of a gases’ vol is empty space, which accounts for gas’ lower density than that of liquids and solids, and explains why gases can be compressed
All collisions are perfectly elastic, there is a transfer of kinetic energy
3. The particles of a gas are in continuous, rapid, and random motion
4. Between gas particles, there are no attractive or repulsive forces.
The average kinetic energy of gas particles depend on the temperature of the gas. • Kinetic energy= ½ mv2 • KE depends only on a gases’ mass, since they have constant velocity • Speeds increase when temp increases, decrease when it decreases • All gases at the same temperature have the same average KE • Lighter gas particles have higher speeds
Kinetic Theory of and Nature of Gases • Many gases behave closer to ideally at lower pressures and higher temperatures
5 Properties of gases • Expansion • Fluidity • Low Density • Compressibility • Diffusion and Effusion
Expansion • Gases will fill any container to take its shape
Fluidity • Gas particles glide easily past each other, so they flow easily
Low Density • 1/1000 the density of a liquid or solid
Compressibility • Particles can be crowded close together by increasing the pressure
Diffusion and Effusion • Diffusion-Spontaneous mixing of particles of 2 substances, caused by random motion • Effusion- gas particles passing through a small opening by random motion
Real gas • Gases that don’t behave as ideal gases. • They deviate from ideal gas befavior because the particles occupy space and exert atractive forces on each other • Deviate the greatest when: • Pressure is high and temperature is low—the particles are closest together
Gases that behave most closely to ideal • Those whose particles do not attract • Nonpolar gases and noble gases • #4. Which gases deviate the most from ideal behavior (the ones that are polar and do attract) He, O2, H2, H2O, N2, HCl, NH3 • Answer: H2O, HCl, NH3