Phase Change Diagram Lab: Changes Of State For Salt Water
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2Name __________________________________ Date ______________________ Period _________
Phase Change Diagram Lab: Changes of State for Salt Water
o
o
It is a well established fact that ice made from pure water will melt at 0
C and boil at 100
C. If
impurities are added to the water then the melting point and the boiling point will change. The greater
the amount of impurities the greater will be the change in the melting and boiling points.
Purpose: In this lab you will determine the Phase Diagram for salt water. You will start with a mixture
of salt water and ice and proceed to turn the solution into a gas. Along the way you will record the
temperature and then graph the data to develop a "Phase Diagram" for the solution.
Hypothesis:_________________________________________________________________________
___________________________________________________________________________________
Materials:__________________________________________________________________________
Procedure:
1.) Set up a ring stand with a test tube clamp to hold the test tube. Place the alcohol burner under the test
tube. DO NOT LIGHT THE BURNER.
2.) Half fill a test tube with equal amounts of the salt water and ice. Insert the test tube into the test tube
holder. Place a thermometer into the solution and rapidly stir the solution for 30 seconds. Record the
initial temperature when it reaches its coldest measurement. Continue to record the temperature every
30 seconds until the ice has completely melted. This takes about 5 minutes.
3.) AFTER all the ice is melted light the alcohol burner with a match. Put the alcohol burner under the
test tube. Keep the flame in contact with the bottom of the test tube.
4.) Continue to stir the solution and record the temperature every 30 seconds. YOU MUST STIR
RAPIDLY. When the solution boils continue recording for another 3 minutes then stop. DO NOT STOP
STIRRING or the solution will boil over. Immediately remove the flame from under the test tube.
5.) Graph the results of the Temperature vs. Time on a piece of graph paper. Remember DO NOT
connect the dots. Find the trend in the data and draw straight lines.
Data Table:
Time
Temp
Time
Temp
Time
Temp
Time
Temp
Time
Temp
0 sec
3:30
6:30
9:30
12:30
0:30
4:00
7:00
10:00
13:00
1:00
4:30
7:30
10:30
13:30
1:30
5:00
8:00
11:00
14:00
2:00
5:30
8:30
11:30
14:30
2:30
6:00
9:00
12:00
15:00
Results: (explain any patterns or trends that you see in the data)
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
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Conclusion: be sure to restate your hypothesis, use the results to support your conclusion and then
explain if your hypothesis was correct or incorrect.
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
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