Challenge

1
Challenge

• Read the problem with your group, and draw a
  representative heating/cooling curve.
• Calculate the heat gained/lost at each segment of
  the curve discussed in the problem.
• Calculate the final answer to the problem.
• Divide duties prepare for the presentation
• One person will draw the curve on the board for
  the class to copy.
• Two group members will name the equations used
  and record the heat answers on each segment of
  the graph.
• A final group member will show the final
  calculation and record the final answer on the
  board.

2
Curve 1

• Calculate the heat (in J) required to raise the
  temperature of a 4.5-gram sample of sulfur from
  103C to 503C.
• Boiling point 444.75C
• Freezing point 113C
• ?H fusion 1.23 kJ/mol
• ?H vap 9.62 kJ/mol
• c 0.710 J/gC

3
Curve 2

• Calculate the heat (in kJ) lost from a 32.5-gram
  sample of water as the temperature cools from
  74C to -7C.
• ?H fusion 6.02 kJ/mol
• ?H vap 40.6 kJ/mol
• C solid 2.03 J/gC
• C liquid 4.184 J/gC
• C vapor 1.7 J/gC

4
Curve 3

• A 6.5-gram sample of tin is heated from 200C to
  2400C. How much heat (in kJ) is needed?
• Boiling point 2270C
• Freezing point 232.06C
• ?H fusion 7.2 kJ/mol
• ?H vap 290.5 kJ/mol
• c 0.227 J/gC

5
Curve 4

• A 14.6-gram sample of potassium is cooled from
  700C to 45C. How much heat (in J) is released?
• Boiling point 774C
• Freezing point 63.8C
• ?H fusion 2.4 kJ/mol
• ?H vap 77.2 kJ/mol
• c 0.750 J/gC

6
Curve 5

• A 5.0 sample of silver is cooled from 1200C to
  72C to make a ring. How much heat (in J) is
  released?
• Boiling point 2212C
• Freezing point 962.1C
• ?H fusion 11.8 kJ/mol
• ?H vap 256.1 kJ/mol
• c 0.235 J/gC

7
Curve 6

• A sample of 4.9 grams of water is cooled from
  114C to -8C. How much heat (in J) is
  released?
• ?H fusion 6.02 kJ/mol
• ?H vap 40.6 kJ/mol
• C solid 2.03 J/gC
• C liquid 4.184 J/gC
• C vapor 1.7 J/gC