Thermal energy transfer

• the internal energy of a body is the sum of the randomly distributed kinetic and potential energies of all its particles
• a system is a group of bodies considered as a whole
• a closed system does not allow matter to be transferred in or out of it
• how do you decrease the internal energy of a closed system

  by cooling it or by doing work to remove energy from the system
• how do you increase the internal energy of a closed system

  by heating it or by doing work to transfer energy to the system
• when an object changes state its internal energy changes but its kinetic energy stays the same. This is because the only potential energy of the particles is altered
• the specific heat capacity of an object is the amount of energy needed to raise the temperature of 1kg of the substance by 1K/1C
• what is the equation for SHC

  Energy = mass x SHC x change in temp
• continuous-flow heating is when a fluid flows continuously over a heating element. As it flows energy is transferred to the fluid
• how can you use a continuous-flow calorimeter to find specific heat capacity?

  • record the flow rate and temperature difference of the water and also current and potential difference
  • energy supplied to the water is Q1=m1cδθ+H, ( H is heat lost)
  • repeat the experiment changing the p.d of the power supply and the flow rate so δθ is constant to find Q2
  • rearrange the equation to find C
  • since q is electrical energy supplied over time do Q = VIt and calculate the specific heat capacity of water
• the specific latent heat of fusion or vaporisation is the quantity of thermal energy required to change the state of 1kg of a substance
• the larger the mass of a substance the more energy it takes to change its state
• $Q =$$ml$where Q is energy m is mass and l is latent heat of vaporization/latent heat of fusion
• the work done in changing the volume of a gas at a constant pressure is $work done =$$p\triangle v$