SCIENCE 08 CHEMISTRYNotebook Page E
EXPERIMENT # 2
CHANGES IN PHASE
PROBLEM:
1.To distinguish the three states (phases) of matter.
2.To determine whether it is possible to change matter from one state (phase) to another.
HYPOTHESIS:
The three observable states of matter will be , , and .
It (will, will not) be possible to change matter from one state (phase) to another by changing the .
APPARATUS AND MATERIALS:
Bromine tube600 mL beakerHot plates or bunsen burners
Iodine tubeUtility clampsRing clamp & wire gauze
Water/alcohol mixtureSupport standsStriker for bunsen burner
Crushed iceTest tubeSmall cardboard box
Wood's metal (alloy)Stirring rodBeaker tongs
250 mL beakerErlenmeyer flaskRubber tubing with glass inserts
PROCEDURE: (DEMONSTRATIONS)
PART
I: BROMINE TUBES:1.Observe the glass tube containing bromine at room temperature and low pressure. Record the colour(s) and phase(s) of bromine present in Table
I.CAUTION:BE EXTREMELY CAREFUL NOT TO BREAK THE BROMINE TUBE BECAUSE BROMINE IN ANY STATE IS DANGEROUSLY REACTIVE AND VERY CORROSIVE !
2.Cool the glass tube containing bromine at high pressure by placing the bottom of the tube in the mixture of ice water and alcohol. As the bromine cools record the colour(s) and phase(s) of bromine present in Table
I both as it first cools and after it has cooled for some time.3.Remove the bromine tube from the ice water bath and record the colour(s) and phase(s) of bromine present in Table
I as it warms back to room temperature.PART
II: IODINE TUBES:4.Observe the glass tube containing iodine at room temperature. Record the colour(s) and phase(s) of the iodine in Table
I.5.Place the iodine tube in a hot water bath in a 600 mL beaker. Record the colour(s) and phases(s) of the iodine in Table
I.
EXPERIMENT #2: PHASE CHANGES PAGE 2Notebook Page E
PART
III: WOOD'S METAL:6.Observe a piece of Wood's metal at room temperature. Place the metal in a 250 mL beaker of hot water and heat the water to a gentle boil. After the metal has been heated attempt to stir it with a stirring rod. Record the colour and phase of Wood's metal in Table
I before and after heating.7.Carefully pick up the beaker with beaker tongs and pour off most of the hot water into the sink. Pour the liquid metal into a small cardboard box. Allow the Wood's metal to cool to room temperature. Record in Table
I the colour and phase of Wood's metal returned to room temperature.PART
IV: WATER:8.Place some crushed ice in the bottom of an erlenmeyer flask and insert the stopper and tubing into the top of the flask. Set the flask onto the support stand, ring clamp and wire gauze. Use a utility clamp to hold it in place. Use a utility clamp to support a test tube in the upright position on the opposite side of the stand with the other end of the tubing inserted into the test tube. Place the bunsen burner under the flask and gently heat the contents until all of the ice melts. Alternatively use a hot plate for heating without any wire gauze.
9.Continue to heat the water until it gently boils. Record any changes in Table
I.10.Record the appearance of the material collecting in the test tube in Table
I. If necessary soak a paper towel in cold water and wrap the towel around the rubber tubing to cool the water vapour. Boil the water in the flask gently for a few minutes to obtain sufficient material in the test tube.OBSERVATIONS:
Write the following: "Refer to Table
I". Record all observations as described in the Procedure section in Table I.DISCUSSION:
1.Write the following: "Refer to Table
II". Name the type of the phase change that occurred in each of the materials studied in each part of the experiment by completing Table II.
2.Explain what must be done to cause bromine, iodine, and water to change to a gas and Wood's metal to change to a liquid.
3.Explain what must be done to cause the bromine and Wood's metal to change to a solid and water vapour to change to a liquid.
CONCLUSION:
Make a judgement statement about your original hypothesis and answer the two questions in the problem.
EXPERIMENT #2: PHASE CHANGESNotebook Page E
TABLE I: OBSERVATIONS OF PROPERTIES
MATERIALTEMPERATURECOLOURPHASE(S)
BROMINEROOM
START TO COOL
COOLED MORE
WARMED TO ROOM
IODINEROOM
WARMED
WOOD'S METALROOM
WARMED
COOLED TO ROOM
WATERCOLD
START TO WARM
WARMED MORE
COOLED TO ROOM
EXPERIMENT #2: PHASE CHANGESNotebook Page E
TABLE II: PHASE CHANGES
MATERIALDESCRIPTIONNAME OF
PHASE CHANGE
BROMINEGAS TO LIQUID
LIQUID TO SOLID
SOLID TO LIQUID
LIQUID TO GAS
IODINESOLID TO GAS
WOOD'S METALSOLID TO LIQUID
LIQUID TO SOLID
WATERSOLID TO LIQUID
LIQUID TO GAS
GAS TO LIQUID