Heating and cooling curves and latent heatIB MYP Physics: Mind map

Exam questions on Heating and cooling curves and latent heat

1. A student heats a beaker containing 0.20 kg of ice at −10 °C using an electric heater that supplies energy at a constant rate. She records the temperature every minute. The temperature rises to 0 °C in the first 30 seconds, stays at 0 °C for the next 8 minutes while the ice melts, then rises steadily to 100 °C over the next 10 minutes, and stays at 100 °C while the water boils.
   Explain why the temperature stays at 0 °C while the ice melts, even though the heater continues to supply energy.2 marks
2. In many hot countries, people store drinking water in porous clay pots. Water slowly seeps through the pot to its outer surface and evaporates there. Even on a very hot day, the water inside the pot stays cooler than the air outside.
   Explain why evaporation cools the water inside the pot.2 marks
3. A student places 0.20 kg of ice at 0 °C in a beaker and heats it with a 500 W heater. All of the heater's energy is transferred to the ice. The specific latent heat of fusion of ice is 334 000 J/kg. The temperature stays at 0 °C until all of the ice has melted.
   Calculate the energy needed to melt all of the ice, and the time this takes.3 marks