Unit 1- Thermodynamics  

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Phases

• Solid- Crystalline structure, non-compressible
• Liquid- no structure, but touching, non-compressible
• Gas- No structure, spread out, compressible.

Physical properties:

→Properties that can be used to identify the substance(element)

• Melting point- point when a solid becomes a liquid
• Boiling point(vaporization)-point when a liquid becomes a gas  (BP)
• Freezing point(solidification)-point when a liquid becomes a solid (FP)
• Density-how closely packed matter is in a given volume
• Atomic Radius(Pg 10+11 on reference table)-refers to the space a specific element occupies.

Energy:

• Potential energy- stored energy
• Kinetic energy- (temperature? Kind of but not really)- energy of the motion of particles

Temperature Units:

• Temp is the average measure of kinetic energy.
• Celcius
• Kelvin- absolute zero (no zeros)
• conversion- K= c + 273

Phase Changes:

• Endothermic- Absorb heat
• Exothermic- release heat

Calculating the change of heat:

• water:
• Heat of fusion 334 j/g (solid to liquid and back/ melting point)
• Heat of Vaporization 2260 j/g (liquid to gas and back/ boiling point)
• Specific Heat capacity 4.18 j/k(g) (Changes temp, but not phase)
  • All on reference table (Physical constants of water)
• equation for Heat of fusion- q=mHf
• equation for Heat of Vaporization- q=mHv
• equation for specific heat capacity- q=mCAT
  • m= mass
  • H= heat (of fusion or vaporization depending on f and v)
  • C= specific heat capacity
  • AT = Delta temp (difference in temp)

Gases:

• Particles are traveling in straight-line paths and are randomly distributed
• No definite shape or volume
• Large distances between particles, low densities
• Can be compressed
• Can be liquified at low temperatures and high pressures

Standard Pressure Temperature: (STP)

• Pressure: 1 atm or 101.3 kPa or 760 torr
• Temperature: 0 C or 273 K

Boyle’s Law:

• relationship between pressure and volume
• says that the volume occupied by a gas is inversely proportional to the pressure exerted on the gas

Charles’s Law:

• Describes the relationship between volume and temperature
• Says that the volume occupied by a gas is directly proportional to the temperature(in kelvin)
• equation- V1/T1 = V2/T2

The combined gas law:

• combines boyles and charles law
• Formula(On back of reference table) - (P1)(V1)/T1 = (P2)(V2)/T2

Kinetic Molecular Theory: (KMT)

• gases move in a random, constant, straight line motion (Ideal gas)
• Have negligible volume (Ideals gas)
• no attraction between particles (Ideal gas)
• If gas molecules do collide no energy is lost or gained (Ideal gas)
  • (none of this is actually true but we pretend it is to make the math work out, that’s why it says “Ideal Gas”)

Ideal Gas Vs. Real Gas:

• Ideal Gas - Follows all rules above for gas.
• Real Gas - gas molecules do have a volume and weak attractive forces
  • Real Gasses act more like Ideal gasses when there is a higher temperature, and lower pressure.

Liquids:

Vapor Pressure:

• The pressure that vapor exerts when the temperature of a liquid increases.
• Vapor pressure has a greater influence on boiling than temperature.
• A liquid will boil when its vapor pressure equals the pressure of the liquid above it
  • Table for vapor pressure is on reference table.

Calorimetry:

• heat stored in chemical bonds(like calories in your food)
• Food labels are actually kilocalories
• Specific heat-the heat required to increase the temperature of a substance by 1 degree
  • The Specific heat of water is on the reference table

Other: (Things to remember)

• The two elements that are liquid at room temperature are Bromium, and mercury
• The two elements that sublime at STP are Iodine, and Carbon Dioxide
• Sublimation- Solid to gas.
• When the volume increases, the pressure decreases.

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Next Unit: Unit 1.5 (Add-on to Unit 1)

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