Name: Period: Date: EN


Graphing a Phase Change


Water is a remarkable substance. It is the only common material that exists in all three states on our planet. When water changes in state, energy is involved. In this lab youll investigate the relationship between temperature and phase changes.



Insulated Cup

Test Tube

Mixture of Salt and Ice


Tap Water

**If you spill the ice and salt mixture, wipe it up immediately with a freshly rinsed sponge. If it dries, the mixture leaves a crusty salt residue.



  1. Fill your insulated cup about 2/3 with ice, then add a full scoop of salt.
  2. Stir the mixture to make a cold slush.

What is the normal melting temperature of ice?

  1. Measure the temperature of the ice/salt mixture.


Temp of ice/salt mixture:

  1. Rinse the thermometer in tap water.
  2. Pour 2-3 cm of tap water into the test tube. Measure the initial temperature of the water (0 minutes).
  3. Place the test tube in the middle of the insulated cup. Pack the salt-ice mixture around the test tube so that the top of the ice is above the water in the test tube. Continue recording the temperatures each 30 seconds in the data table below. Note the points where first you notice the formation of ice and when the water seems to be frozen solid.

** The thermometer will freeze into the ice in the tube. DO NOT BREAK THE THERMOMETER TAKING IT OUT!

  1. Stop your experiment when the temperature has cooled to -10C. Do not try to pry the thermometer out of the ice. It will break. Instead, rest the test tube with the frozen thermometer in a beaker of warm water, until the thermometer moves easily.
  2. Rinse the insulated cup and the test tube with plenty of water. Make sure to wash away any salt residue.
  3. Graph your results. Make a point-to-point line (not a best-fit line).
  4. After we take notes today, draw a dotted line on your graph to show how you would expect the experimental data to look.


Time (min)






















































































  1. How does a phase change show on your graph?


  1. At what temperature did the phase change?


  1. What was the state of matter of the fresh water at the start?


  1. In what phase was the fresh water when you finished?


  1. What is the name of the change in phase that took place in the test tube?


  1. What phase change is happening in the ice & salt mixture?


  1. Did the phase change inside the test tube absorb or give off energy?


  1. Why was salt added to the ice?


  1. If, after the ice has melted, the wet apparatus were just left in the room for several weeks, what additional change in state would take place?



  1. Draw a rough sketch of a graph that shows a substance cooling and making TWO changes in phase.

Text Box: Temperature (C)
























***Attach the graph of your results to this sheet before you turn it in!