1. 1
   An ice sculptor places a large block of ice in a warm exhibition room and monitors it over several hours as it slowly warms up, melts, and the resulting water warms further.

   (a)

   What is meant by the internal energy of a system?

   [1 mark]

   • AThe total kinetic energy of the particles only
   • BThe total kinetic energy and potential energy of all the particles in the system
   • CThe total mass of all the particles in the system
   • DThe energy released when the system is destroyed

   (b)

   While the ice is warming up but still fully solid, what happens to its internal energy as it absorbs heat from the room?

   [1 mark]

   • AIt decreases
   • BIt stays exactly the same
   • CIt increases, and the ice's temperature rises
   • DIt increases, but the ice's temperature stays constant

   (c)

   Once the ice reaches 0 °C and starts to melt, explain what happens to its temperature while melting is taking place, and explain where the absorbed heat energy is going instead.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A metalworker in a forge heats a 2 kg block of aluminium (specific heat capacity 900 J/kg°C) from 20 °C to 70 °C, well below its melting point, in order to shape it more easily without melting it.

   (a)

   A metalworker heats a 2 kg block of aluminium (specific heat capacity 900 J/kg°C) from 20 °C to 70 °C. Which equation should be used to calculate the energy needed?

   [1 mark]

   • AΔE = mcΔθ
   • BΔE = mL
   • CΔE = m/cΔθ
   • DΔE = c/mΔθ

   (b)

   What is the definition of specific heat capacity?

   [1 mark]

   • AThe energy required to melt one kilogram of a substance
   • BThe energy released when one kilogram of a substance cools by one degree Celsius only while changing state
   • CThe total kinetic energy of one kilogram of a substance
   • DThe energy required to raise the temperature of one kilogram of a substance by one degree Celsius

   (c)

   Calculate the energy required to heat the aluminium block from 20 °C to 70 °C.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A mountaineer at a high-altitude camp continuously heats a sealed pot containing solid ice, recording its temperature every 30 seconds as it warms, melts, heats further as a liquid, and eventually boils into water vapour.

   (a)

   A mountaineer boils water in a sealed pot at a high-altitude camp and records the temperature of the water every 30 seconds as it is heated continuously, from solid ice through to boiling water vapour. Describe what a graph of temperature against time would look like for this process, referring to the sections where temperature rises and where it stays flat.

   [3 marks]

   (b)

   The specific latent heat of vaporisation of water is much greater than its specific latent heat of fusion. Using the equation E = mL, explain what this tells the mountaineer about the relative amounts of energy needed to melt a given mass of ice compared with boiling the same mass of water, and explain in particle terms why boiling requires more energy than melting.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A food scientist is developing a new type of ice pack for treating sports injuries, and wants it to absorb as much heat as possible from an injury while staying at a constant, safe temperature for the longest possible time before it fully melts.

   (a)

   A food scientist is developing a new type of ice pack that must absorb a large amount of heat from an injury while staying at a constant, safe temperature for as long as possible. Explain, using the concept of internal energy and specific latent heat, why a substance that is melting (changing from solid to liquid) is more effective at this than a solid substance simply warming up, and explain how the choice of substance's specific latent heat of fusion would affect the ice pack's performance.

   [6 marks]

   (b)

   A colleague suggests simply using a block of solid metal, pre-cooled to a very low temperature, instead of a melting substance for the ice pack. Evaluate this suggestion, comparing it with a melting substance, in terms of internal energy and how the temperature of each would change while absorbing heat from an injury.

   [6 marks]

   Total for question 4: 12 marks

End of questions