JUST A PHASE

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LESSON 7

• JUST A PHASE

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OBJECTIVES

• DISCUSS YOUR CURRENT KNOWLEDGE OF PHASE CHANGE.
• OBSERVE WHAT HAPPENS TO ICE AS IT IS HEATED.
• MEASURE THE TEMPERATURE OF ICE WATER AS IT IS
  HEATED.
• PLOT A GRAPH OF YOUR MEASUREMENTS.
• INTERPRET YOUR GRAPH AND OTHER OBSERVATIONS.

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MATERIALS

• 1 BURNER
• 1 HEATING STAND
• 1 THERMOMETER
• 1 250-mL BEAKER
• 1 METRIC RULER
• 3 TO 4 ICE CUBES
• STOP WATCH

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GETTING STARTED

• READ THE INTRODUCTION ON
• P. 65 IN YOUR STUDENT GUIDE.
• IN YOUR GROUPS, DISCUSS AND RECORD ANSWERS TO THE
  QUESTIONS ON PG. 65.
• YOULL HAVE ABOUT 5 MINUTES TO COMPLETE THIS
  TASK.
• BE PREPARED TO SHARE.

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• WHAT IS THE DIFFERENCE BETWEEN HEAT AND
  TEMPERATURE?
• WHAT DO THE TERMS MELTING POINT AND BOILING
  POINTS MEAN?

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PROCEDURE

• SET UP THE APPARATUS AS SHOWN ON FIGURE 7.1 ON
  PG. 66 IN YOUR STUDENT GUIDE.
• BECAUSE THIS MAY BE THE FIRST TIME YOUVE USED A
  BURNER, LETS DISCUSS HOW IT IS USED.
• LETS DISCUSS THE SAFETY TIPS.

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SAFETY TIPS

• TIE BACK LONG HAIR AND SLEEVES.
• WEAR SAFETY GOGGLES THROUGHOUT THE INQUIRY.
• BE CAREFUL WHEN YOU HANDLE THE APPARATUS.
• NO MOVEMENT AROUND WHILE THE BURNERS ARE LIT.
• DO NOT REACH ACROSS A FLAME.

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LETS READ THE ENTIRE PROCEDURE BEFORE WE BEGIN.
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• POUR COLD TAP WATER, TO A DEPTH OF 1 cm INTO THE
  BOTTOM OF THE BEAKER.
• COLLECT 3 TO 4 ICE CUBES OR TO A DEPTH OF 3 cm IF
  WE USED CRUSHED ICE.
• PLACE THE THERMOMETER IN THE ICE WATER AND ALLOW
  IT TO STAND FOR A FEW MINUTES.

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• THE TEACHER WILL COME AROUND AND LIGHT YOUR
  BURNER. ADJUST THE FLAME TO ABOUT 5 cm HIGH.
• DO NOT START HEATING THE ICE WATER YET.
• MEASURE THE TEMPERATURE OF THE ICE WATER AND
  RECORD THE TEMPERATURE NEXT TO TIME 0 IN TABLE 1
  ON STUDENT. SHEET 7.1.

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• PUT THE BEAKER ON THE HEATING STAND AS SHOWN ON
  FIGURE 7.3 ON PG. 67. SLIDE THE STAND GENTLY OVER
  THE BURNER. DO NOT ADJUST THE FLAME OF YOUR
  BURNER WHILE YOU ARE HEATING THE ICE.
  IMMEDIATELY START MEASURING THE TIME.

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• TAKE THE TEMPERATURE EVERY 30 SECONDS AND RECORD
  IT.
• RECORD ANY CHANGES IN TABLE 1.
• WHEN THE WATER BOILS, CONTINUE TO TAKE READINGS
  FOR 3 MINUTES MORE

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• EXTINGUISH THE BURNER AND ALLOW THE APPARATUS TO
  COOL.

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CLEAN UP

• MAKE SURE ALL MEMBERS OF YOUR GROUP HAVE
  COMPLETED YOUR RESULTS AND OBSERVATIONS.
• WHEN THE APPARATUS HAS COOLED, POUR OUT THE WATER
  FROM THE BEAKER AND RETURN THE BURNERS TO THE
  TOTE TRAY.

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PLOTTING THE GRAPH

• PARTS OF THE GRAPH
• TITLE
• LABEL X AND Y AXIS (VARIABLES AND UNITS)
• LARGEST NUMBER INCREMENTS
• USE APPROPRIATE KIND OF GRAPH
• KEY IF NEEDED
• OBSERVATIONS ON GRAPH AT APPROPRIATE TEMPERATURES

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REFLECTIONS

• HOW DOES THE SHAPE OF THE CURVE ON YOUR GRAPH
  COMPARE TO THOSE PRODUCED BY OTHER GROUPS?
• DO ANY CHANGES IN THE DIRECTION OF YOUR CURVE
  MATCH THE POINT AT WHICH THE ICE MELTED OR THE
  WATER BOILED?

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DRAW THE FOLLOWING DIAGRAM ON STUDENT SHEET 7.1,
QUESTION 3

• FILL IN THE 3 PHASES OF MATTER
• BELOW THE BOXES.
• PUT THE 3 PHASES OF WATER IN THE BOXES.
• USE ARROWS TO SHOW THE CHANGE OF PHASE FROM ONE
  FORM OF THE WATER TO ANOTHER.

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MELTING
EVAPORATING
ICE
STEAM
WATER
FREEZING
CONDENSING
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• LABEL THE ARROWS USING THE TERMS MELTING,
  EVAPORATING, FREEZING, AND CONDENSING.
• ON STUDENT SHEET 7.1 FINISH QUESTION 3 BY WRITING
  A PARAGRAPH THAT EXPLAINS THE SHAPE OF THE CURVE
  ON YOUR GRAPH.