Chemistry Final Exam Study Guide

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Chemistry Final Exam Study Guide
Shara Shonn

Chapter 10 –
Temperature – the measure of the average kinetic energy of the molecules or atoms in a system * The higher the kinetic energy the higher the temperature Vaporization –
* Vaporization – the process by which a liquid or solid changes to a gas * Occurs when particles have enough energy to escape intermolecular forces Evaporation –
* Evaporation – the process by which particles escape from the surface of a non-boiling liquid and enter the gas state Boiling –
* Boiling change from a liquid to a gas in the form of bubbles throughout a liquid Formation of Solids –
* When temperature decreases the average energy of particles decreases * This allows intermolecular forces to hold particles in an orderly arrangement * Freezing (solidification) – change from a liquid to a solid by the removal of heat Energy and Change of State –

* During a phase change the temperature of a system does not change * Heat energy is either absorbed or released by molecules

Kinetic-Molecular Theory –
* Particles of matter are always in motion
* Explains the properties of solids, liquids, and gases in terms of the energy of particles & the forces between them Theory of Gases –
* Ideal gas – a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory * Real gas – does not behave completely according to the theory Five Assumptions –
1. Gases consist of tiny particles that are far apart
* 1000 times the volume of a solid
* Most of volume is empty space
2. Collisions between particles & between particles and containers are elastic collisions * Elastic collision – no net loss of energy
3. Gas particles are in constant motion
* They possess kinetic energy
4. There are no forces of attraction between gas particles * When particles collide they simply bounce apart
5. The temperature of a gas depends on the average kinetic energy * KE = ½mv2 m = mass v = velocity
* Since all particles of a specific gas have the same mass, kinetic energy depends only on the speed Nature of Gases –
* Expansion
* Gases expand to fill any container
* Assumptions 3 & 4
* Gas particles move in all directions
* No attractive forces between them
Fluidity –
* Low attractive forces (#4) enable gas particles to glide past one another * Liquids and gases are both fluids
Low Density –
* Density is about 1/1000 of a liquid (#1)
* Compressibility – since particles are so far apart (#1) they can be compressed together Diffusion and Effusion –
* Diffusion – spontaneous mixture of 2 substances due to their random motion (#3) * Effusion – process by which gas particles pass through tiny openings * Rate of effusion is directly proportional to velocity of particle * Molecules of low mass effuse more quickly

Graham’s Law of Effusion –
* At a given temperature, the rates of effusion of gas molecules are inversely proportional to the square roots of their molar masses * Equation : rate1/rate2 = √(M2/M1) M = molar masses 1= lightest gas 2 = heaviest gas

Deviations of Real Gases –
* Real gas – does not behave completely according to the kinetic-molecular theory * At high pressure and low temperature, gas particles will not have enough kinetic energy to overcome attractive forces * The more polar the gas molecules the stronger the intermolecular attraction and the more deviation from kinetic-molecular theory Liquids –

* Least common state of matter
* Kinetic-molecular theory
* Particles of liquids are in constant motion
* Particles are close together and therefore are attracted to each other by intermolecular forces * Particle mobility
* Particles of a liquid are free to move
* Liquids take the shape of their container
Relative High Density (liquid) –
* Only slightly less dense...
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