Thermal

• The three phases of matter are:

  • Solid
  • Liquid
  • Gas
• Particles in a solid vibrate about fixed positions in a regular lattice. They're close together, and are held in position by strong forces of attraction.
• Particles in liquids are constantly moving around and are free to move past one another. The attraction between particles in liquids is weaker than in solids. They are fairly close together but have an irregular arrangement
• Particles in gases are far apart and free to move around with constant random motion. They are not in any order. There are no forces of attractions in an ideal gas.
• the idea that solids, liquids and gases are made of tiny moving or vibrating particles is called the kinetic model of matter
• To observe Brownian motion. Start by putting some smoke into a glass jar. Use a glass rod to focus light from a lamp into the glass jar. Observe the particle using a microscope. The smoke particles appear as bright specs moving randomly from side to side, and up and down.
• The random movement of particles suspended in a fluid is called Brownian motion
• Internal energy is the sum of the random distribution of kinetic and potential energies associated with the molecules of a system
• Thermal equilibrium occurs when there is no net-flow of energy between two or more systems
• When a hot object is placed in cold water, heat transfers from the hotter object to the cooler object until they are both at the same temperature. This process continues until there is no further change in temperature
• When a substance changes phase the internal energy changes. However the kinetic energy and the temperature stay the same. The energy is used to increase the substances potential energy and break bonds.
• Temperature (In Kelvin) = temperature (in Celsius) + 273
• A student needs to heat a flask of liquid to 345 K. What will the flask's temperature be in Celsius?

  72°C
• If a person making a pie places hot filling into a cool pastry, what will be the direction of new-flow of thermal energy?

  From the filling to the pastry
• A hot pie eventually comes to thermal equilibrium with the room. How do we know that the pie filling is at equilibrium with the pastry?

  If the whole pie is in equilibrium with the room then the filling must be in equilibrium with the pastry
• Brownian motion occurs when heavy particles in a fluid collide with smaller particles. For example smoke particles in the air.
• what is the lowest temperature an object an theoretically reach called?

  Absolute zero
• The specific heat capacity (c) of a substance is the amount of energy needed to raise the temperature of 1 kg of the substance by 1 K
• Energy change (E) = Mass (m) x specific heat capacity (c) x temperature change (T)
• to measure the specific heat capacity of a solid. Measure the mass of the solid and its initial temperature. Place an electric heater and a digital thermometer into two holes in the solid. Make sure to surround the solid with insulating material. Connect a voltmeter and an ammeter to the electric heater to calculate the heaters power. Turn on the heater and measure how long the solid takes to heat up 10 Kelvin. Use the equation E = V x I x t to measure the energy output of the heater. Then use specific heat capacity = Energy / mass x change in temperature
• to measure the specific heat capacity of a liquid. Measure the mass of the liquid and its initial temperature. Place a heating coil and a digital thermometer into the liquid. Make sure to surround the liquid with insulating material. Connect a voltmeter and an ammeter to the heating coil to calculate the heaters power. Turn on the heater and measure how long the liquid takes to heat up 10 Kelvin. Use the equation E = V x I x t to measure the energy output of the heater. Then use specific heat capacity = Energy / mass x change in temperature
• Estimating specific heat capacity:

  • Heat the substance of known mass up to a known temperature
  • Quickly transfer the substance into an insulated container containing a known mass of water at a known temperature
  • The substance will heat the water, measure the temperature once the temperature of the water has reached a steady value
  • The energy lost by the substance will be the same as the energy gained by the water
• Specific latent heat (L) is the amount of thermal energy required to change the state of 1 kg of a substance
• Energy change (E) = mass (m) x specific latent heat (L)
• when a liquid freezes into a solid, it absorbs energy so the temperature increases
• When a gas condenses back into a liquid, it releases energy so the temperature decreases
• Specific latent heat of fusion:

  • set up two funnels over two beakers
  • connect a heating coil up to an ammeter and a voltmeter
  • put two equal masses of ice into both funnels, placing the heating coil into one of the funnels and turning it on for three mins
  • measure current and voltage through the coil, calculating the energy given off the heater using E = V x I x t
  • measure the mass of the water in both beakers and subtracting the mass in the beaker without a heater from the beaker with a heater
  • Use L = E/m to get specific latent heat
• Measuring specific latent heat of vaporisation:

  • Fill an insulated beaker with water
  • Connect a voltmeter and an ammeter to a heating coil and place it in the water
  • Place the beaker on a scale
  • Record the mass on the scale and turn the heater on and start a timer
  • When mass has decreased by 15 g turn the heater and the timer off. Use E = v x I x t to calculate energy given by the heater
  • Record the new mass and substract it from the original mass
  • Use L = E/m to calculate specific latent heat
• Boyle's law states at a constant temperature the pressure (p) and volume (V) of an ideal gas are inversely proportional
• pV = constant
• p is directly proportional to 1/V
• Investigating Boyle's Law:

  • oil traps air pockets in a sealed tube of fixed dimensions
  • use a tyre pump to increase the pressure on the oil
  • use a Bourdon gauge to record the pressure
  • measure the volume of air when the system is at atmospheric pressure by multiplying the length of the part of the tube containing air by pi x radius squared
  • Gradually increase the pressure by a set interval making sure to wait a few seconds each time to give the temperate time to stabilise
  • Note down the pressure and volume of air each time
  • repeat twice more and calculate a mean
  • plot graph of p against 1/V
• the pressure law states: At a constant volume the pressure (p) of an ideal gas is directly proportional to its absolute temperature (T)
• Investigating pressure law and estimate absolute zero:

  • submerge a stoppered flask of air in water
  • connect the stopper to a bourdon gauge using a short length of tube
  • record temperature of the water and the pressure
  • insert an electric heater few minutes to heat the water and then remove it. Stir the water to ensure uniform temperature
  • Record pressure on the gauge and the temperature then repeat until the water starts to boil
  • p x T should give a constant
  • plot results on a graph and draw a line of best fit
  • estimate absolute zero by extrapolating the line of best fit
• Charles' law states: At a constant pressure, the volume (V) of an ideal gas is directly proportional to its absolute temperature (T)
• What must be true of a gasses mass to obey the three laws?

  A fixed mass
• Avogadro's constant states: one mole of any material contains the same number of particles no matter what the material is
• Number of particles (N) = number of moles (n) x Avogadro's constant (Na)
• p x V/T = constant
• Pressure (p) x volume (V) = number of moles (n) x molar gas constant (R) x temperature (T)