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Sage ­N­Scribe
1) The Sage gives the Scribe step­by­step instructions how to solve a problem
2) The Scribe records the Sage's solution step by step in writing
3) If the Sage is correct, the Scribe praises the Sage. Otherwise, the Scribe coaches, then praises
4) Students switch roles for the next problem
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What happens to the temperature of a block of ice when you put a Bunsen burner underneath it? Sketch what you think the Temperature vs.
Time Graph will look like.
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Heating Curve
http://www.kentchemistry.com/links/Matter/HeatingCurve.htm
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Notice that, in general, the temperature goes up the longer the heating continues. However, there are two horizontal flat parts to the graph. These happen when there is a change of state. The plateaus are also called ____________________. The first change of state is ____________. The temperature _________________ while a substance melts. For water, this temperature is 0°C because the melting point for water is 0°C.
The second change of state is _____________. The temperature __________________ while a substance boils. For water, this temperature is 100°C because the boiling point for water is 100°C.
Heating Curve for Water
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Different substances have different melting points and boiling points, but the shapes of their heating curves are very similar. For example, this is the heating curve for iron, a metal that melts at 1538°C and boils at 2861°C.
Heating Curve for Iron
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Cooling Curves
Cooling curves show how the temperature changes as a substance is cooled down. Just like heating curves, cooling curves have horizontal flat parts where the state changes from gas to liquid, or from liquid to solid.
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Latent Heat
Heating that causes a change in state is termed latent heat. This is seen in the heating curve. As the substance changes state the temperature remains constant. flat part on
graph
Specific Latent Heat: is the heat required to change the state of a unit mass of a substance.
See p.200 for
a table of
specific latent
heat
lf <-specific
latent heat of
fusion
lv <-specific
latent heat of
vapourization
8
Calculate the amount of heat required to completely convert 50 g of ice at ­10 ºC to steam at 120 ºC. Heat is taken up in five stages: 1. The heating of the ice 2. The melting of the ice, 3. The heating of the water, 4. The vaporization of the water 5. The heating of the steam. Homework
p. 200 # 1,2
p. 203 # 4,5,6
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Calculate the amount of heat required to completely convert 50 g of ice at ­10 ºC to steam at 120 ºC. Heat is taken up in five stages: 1. The heating of the ice 2. The melting of the ice, 3. The heating of the water, 4. The vaporization of the water 5. The heating of the steam. 10