1.1.3 Energy Changes in Systems

• Change in internal energy = mass x specific heat capacity x temperature change
• What is change in internal energy measured in?

  Joules.
• What is specific heat capacity measured in?

  Joules per kilogram per degree Celsius (J/kg°C)
• What is temperature change measured in?

  Degrees Celsius.
• The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
• Internal energy is the total energy stored by the particles making up a substance or system.
• What is internal energy comprised of?

  Kinetic and potential energy stores.
• Temperature is a measure of the average kinetic energy of the particles in a substance.
• The particles in a solid have kinetic energy because they are vibrating.
• The particles in a liquid or gas have kinetic energy because they move around.
• A kettle with 0.05 kg of water was heated from 25 °C, to the boiling temperature of 100 °C. The specific heat capacity of water is 4,200 J/kg°C. How much heat energy is required?

  15750J.
• A material with a higher specific heat capacity requires more energy to change its temperature.
• A beaker of water with a mass of 250g was heated until its internal energy increased by 21 kJ. If the water's original temperature was 24 °C, what is its final temperature?(Specific heat capacity of water is 4,200 J/kg°C)

  44 degrees Celsius.
• To heat 20g of aluminium by 1*C requires 18 J of energy. To heat the same amount of gold only requires 2.6 J. Which element must have higher specific heat capacity?

  Aluminium.
• A lump of gold with a mass of 20g was heated to 53 °C, and then allowed to cool down to 28 °C. If gold's specific heat capacity is 130 J/kg°C, how much internal energy did it lose in the cooling process?

  65J.