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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:
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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.
Curve 1 • Calculate the heat (in J) required to raise the temperature of a 4.5-gram sample of sulfur from 103°C to 503°C. • Boiling point = 444.75°C • Freezing point = 113°C • ∆H fusion = 1.23 kJ/mol • ∆H vap = 9.62 kJ/mol • c= 0.710 J/g°C
Curve 2 • Calculate the heat (in kJ) lost from a 32.5-gram sample of water as the temperature cools from 74°C to -7°C. • ∆H fusion = 6.02 kJ/mol • ∆H vap = 40.6 kJ/mol • C solid = 2.03 J/g°C • C liquid = 4.184 J/g°C • C vapor = 1.7 J/g°C
Curve 3 • A 6.5-gram sample of tin is heated from 200°C to 2400°C. How much heat (in kJ) is needed? • Boiling point = 2270°C • Freezing point = 232.06°C • ∆H fusion = 7.2 kJ/mol • ∆H vap = 290.5 kJ/mol • c= 0.227 J/g°C
Curve 4 • A 14.6-gram sample of potassium is cooled from 700°C to 45°C. How much heat (in J) is released? • Boiling point = 774°C • Freezing point = 63.8°C • ∆H fusion = 2.4 kJ/mol • ∆H vap = 77.2 kJ/mol • c= 0.750 J/g°C
Curve 5 • A 5.0 sample of silver is cooled from 1200°C to 72°C to make a ring. How much heat (in J) is released? • Boiling point = 2212°C • Freezing point = 962.1°C • ∆H fusion = 11.8 kJ/mol • ∆H vap = 256.1 kJ/mol • c= 0.235 J/g°C
Curve 6 • A sample of 4.9 grams of water is cooled from 114°C to -8°C. How much heat (in J) is released? • ∆H fusion = 6.02 kJ/mol • ∆H vap = 40.6 kJ/mol • C solid = 2.03 J/g°C • C liquid = 4.184 J/g°C • C vapor = 1.7 J/g°C
Curve 7 • A sample of 7.5 grams of water is heated from room temperature 25°C to 108°C. How much heat (in J) is gained? • ∆H fusion = 6.02 kJ/mol • ∆H vap = 40.6 kJ/mol • C solid = 2.03 J/g°C • C liquid = 4.184 J/g°C • C vapor = 1.7 J/g°C