By experimenting with water as it changes state and investigating some effects of air pressure, students not only learn core ideas in physical science but can deduce the water situation on Mars by applying those concepts. To have students graph the temperature of an ice-water slurry as it is heated and discover the existence of another transition plateau. Key Concepts Water can only be heated to its boiling temperature. The slope of a graph line in this activity shows the rate of temperature change. The temperature of ice water can rise only after all the ice has melted.
Temperature measures the average vibrational energy of a particle or group of particles.
As the water in Activity 1 boiled and the ice in Activity 2 melted, the particles used the energy from the heat source to gain the extra kinetic energy required to change state. As a result, the temperature during these transitions never changed. To have students increase the boiling temperature of water by increasing the pressure in the container. Key Concepts Water boils when its vapor pressure equals atmospheric pressure. As a result, water's boiling temperature is pressure, rather than temperature, dependent.