11. Melting and Boiling

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11. Melting and Boiling

• Scientific Enquiry Question

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• Raj wanted to investigate melting and boiling.
• He set up his apparatus safely and put on his
  safety glasses.
• The teacher put some crushed ice into the
  beaker.
• Raj put the thermometer into the ice.
• He lit the Bunsen burner so the beaker was
  heated gently.
• The graph shows how the readings on the
  thermometer changes.

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S
R
Q
P
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• (a). (i). Write a suitable title for the graph
• ___________________________________________
• (ii). What are the dependent and independent
  variables in this experiment?
• D.V. is ____________________________________
• I.V. is _____________________________________
• (iii). Using the graph for help how long did
  the experiment take? ____________________________
  
• (iv) What are the maximum and minimum
  temperature recordings on the graph?
• _____________ and _______________
• (v). What was the total temperature rise?
• ___________________________________________

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• (b) Which letter on the graph shows
• (i) ice melting? ______ (ii) water boiling?
  ________
• (c) During the experiment, the beaker and its
  contents were quickly removed from the heat and
  weighed on a balance at the following times 0,
  5, 10 and 15 minutes
• (i) At which two times would you expect the
  readings on the balance to be the same?
• __________ minutes and __________ minutes
• (ii). Use scientific reasons to explain why they
  would be the same
• ___________________________________________
• ___________________________________________
• ___________________________________________

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• (d). Between which two of these times was the
  mass of the contents of the beaker changing most
  rapidly?
• __________ minutes and __________ minutes
• (ii). Use scientific reasons to explain why
• ______________________________________
• ______________________________________
• ______________________________________
• ______________________________________

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• (e). Draw the equipment (with labels) to show
• how this experiment would be set up to work.
• Add very brief notes to point out any safety
• worries or hazards to be aware of.

Thermometer Ice Beaker Gauze Tripod Bunsen
burner Heat proof mat
Heat
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• Coaching Notes
• What changes of state are we looking at?
• What is melting/freezing boiling/evaporating?
• What temperatures does pure water boil/melt?
• What safety issues?
• Read off data from the graph
• Time 0 mins Temperature is ?
• 2 ?
• 4 ?
• 6 ?
• 8 ?
• Extension Work
• Notice the temperatures MINUS 20 and PLUS 102 !!
• Can you explain what is going on? No mistakes
  have been made reading the thermometer.
• How could you test the water for impurities?
• Put the pattern seen in the graph into words
• i.e. _at_ point P .. then _at_ Q R S etc.

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• Extension Work
• Notice the temperatures MINUS 20 and PLUS 102 !!
• Can you explain what is going on? No mistakes
  have been made reading the thermometer.
• How could you test the water for impurities?
• Put the pattern seen in the graph into words
• i.e. _at_ point P .. then _at_ Q R S etc.