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Charter 6 - Coggle Diagram
Charter 6
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CHANGES OF STATE
Matter can change between states (physical change rather than chemical change) when the temperature or pressure of a system is changed
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• Heating causes the particles of matter to absorb energy, move more vigorously and separate further apart (weak intermolecular bonds may be broken)
• Cooling causes the particles to move less vigorously and come closer together
Phase Diagram
•A phase diagram shows the various phases (or states) of a system as a function of pressure and temperature
•A phase diagram for a single component system is for a pure compound, for example pure H2O and CO2
A phase diagram summarizes the conditions at which a substance exists as a solid, liquid, or gas and the places where equilibria exist between phases.
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PHASE DIAGRAM FOR WATER
The sublimation point curve (or sublimation point line) is a line where the solid and the gas phase are in equilibrium (the line separates pure solid from pure gas)
•The boiling point curve (aka vapor pressure curve) is a line where the liquid and gas phase are in equilibrium (the line separates pure liquid from pure gas) The normal boiling point of H2O is 100oC at 1 atm
The melting point curve (aka fusion curve) is a line where the solid and the liquid phase are in equilibrium (the line separates pure solid from pure liquid)
The normal melting point of water is 0oC at 1 atm
➢The melting point line for water slopes to the left (negative slope) because as pressure is increased the melting point of H2O is decreased
The triple point occur at 0.006 atm and 0.01oC (at this point the gas, liquid and solid co-exist at equilibrium)
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Properties of Liquid
Viscosity
•Viscosity depends on any factor that can influence the ease with which molecules slip past each other
Viscosity is a measure of the resistance to flow (measured in units called poise, pronounced 'pwahz')
Liquids tend to become more viscous as the size of molecules become larger, as the amount of intermolecular bonding increases and the temperature decreases
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Vapor Pressure
The vapor pressure of a liquid is the pressure of the vapor (gas) above the liquid at a given temperature
•A liquid open to the air will (over time) evaporate completely; however in a closed container some of the evaporated molecules may return to the liquid
•Over time an equilibrium will be established (the rate at which molecules evaporate is equal to the rate at which molecules return to the liquid)
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Colligative Properties
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Solubility- the maximum amount of a solute that will dissolve in a given quantity of solvent at a specific temperature.
When solute is introduced into the volume of solvent, the solvent properties change
Colligative properties are properties of solutions that depend solely on the number of particles dissolved in the solution
Colligative properties depend only on the number of dissolved particles in solution and not on their identity
eg The taste (non colligative property) of 0.1M NaCl is salty but 0.5M of sugar is sweet, however the number of dissolved particles (colligative property) is the same
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