Year 11 Semester 1 exams

• Heat


  energy that is transferred from one body to another as the result of a difference in temperature.
• Temperature


  Temperture is the measure of the average amount of kinetic energy in a particle.
• How temperature is measured

  1. Heat from the environment contacts the thermometer fluid

  2. Atoms in the fluid gain kinetic energy

  3. The column expands

  4. Reaches thermal equilibrium with the environment

  5. Temperature can be read
• All phases of matter expand with higher temperature
• Thermal expansion


  The phenomenon where matter expands with higher temperature
• Heat transfer


  The transfer of kinetic energy from hotter particles to cooler particles through collisions
• Heat transfer occurs


  Temperature of objects changes until thermal equilibrium is reached
• Hot object


  Transfers heat to a cooler hand, causing a hot sensation
• Cold object


  Causes heat to transfer out of a warmer hand, causing a cold sensation
• More heat transferred to an object


  The more its temperature will rise
• Calculating specific heat capacity

  Q(heat loss or gained)=M(mass)C(Specific heat capacity)ΔT(change in temperature)
• The temperature change will always be negative if the substance is being cooled, and positive if it is being heated
• Phase changes


  Transformations between the three phases of matter: solid, liquid, and gas
• Melting and freezing


  Transformations between solid and liquid
• Boiling and condensing


  Transformations between liquid and gas
• Sublimation


  Transformation from solid directly to gas
• Enthalpy change

  The change in heat energy that occurs during a phase change
• Boiling point


  The temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid, and bubbles of vapor form inside the liquid
• Freezing point


  The temperature at which a liquid turns into a crystalline solid
• Melting point


  The temperature at which a crystalline solid melts
• Flat sections on the temperature-time graph


  Represent the phase changes, where heat energy is used to disrupt the lattice energy or hydrogen bonds rather than heating the sample
• Heat of fusion


  The energy exchanged during melting
• Heat of vaporization


  The energy exchanged during boiling
• At atmospheric pressure, water has three phases: solid, liquid, and gas
• Heating an object


  1. Energy is transferred to its thermal energy store

  2. Temperature increases
• Heat transfer


  • Can take place in three different ways depending on the medium involved
  • Conduction in solids
  • Convection in fluids
  • Radiation through empty space
• Conduction


  Vibrating particles transfer energy to neighboring particles
• Heating one end of a metal


  • Energy is transferred to the kinetic energy store of the particles at that end
  • Particles vibrate faster and collide with neighbors more often and with more energy
  • Collisions transfer kinetic energy to neighbors
  • Process repeats until heat is spread out evenly
• Thermal conductivity


  How well objects transfer energy by conduction
• Thermal conductivity


  • Metals have high thermal conductivity and transfer heat rapidly
  • Plastics have low thermal conductivity and are used as insulators
  • Fluids have low thermal conductivity
• Convection


  1. Heated fluid particles gain kinetic energy and move around faster by random diffusion

  2. Warmer, less dense particles rise above cooler, denser particles

  3. Cooler particles sink down and take their place

  4. Cycle repeats as long as fluid is being heated, creating a convection current
• To reduce convection


  Need to stop the free flow of fluids, like sleeping under a blanket
• Conduction and convection both involve particles gaining kinetic energy, but in conduction only the energy is transferred between particles, while in convection the particles themselves move
• Radiation


  1. Energy is carried by infrared waves

  2. All objects constantly absorb and emit radiation

  3. Hotter objects emit more radiation
• Infrared radiation can be felt when putting a hand over a hot barbecue, even without touching it
• Atom


  The fundamental unit of an element, consisting of a nucleus containing protons and neutrons, and electrons that orbit the nucleus
• Nucleus


  • Contains protons and neutrons
  • Protons are positively charged
  • Neutrons are neutral
  • Protons and neutrons have a relative mass of 1
• Electrons


  • Orbit the nucleus
  • About 2000 times smaller than protons or neutrons
  • Have a negative charge of 1-
• Periodic table


  A tabular arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties
• Nucleus symbol


  A box on the periodic table that represents a particular element