Heating & Cooling Curves
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Heating & Cooling Curves Heat vs. Temperature graphs
description
Heating & Cooling Curves. Heat vs. Temperature graphs. Temperature. The differences between solids, liquids and gases can be explained by the particle model: - All substances are made up of particles (atoms, ions or molecules) - PowerPoint PPT Presentation
Transcript of Heating & Cooling Curves
Heating & Cooling Curves Heat vs. Temperature graphs
Temperature
The differences between solids, liquids and gases can be explained by the particle model: -
All substances are made up of particles (atoms, ions or molecules)
These particles are attracted to each other, some strongly and others weakly
These particles move around (i.e. have kinetic energy)
The kinetic energy of particles increases with temperature
Temperature
What is the heating curve?
The heating curve is a graph which represents how a sample changes phases. As heat is added over time, the sample changes temperature and phase accordingly. Thus heating curve.
What are the parts of the heating curve?
What are the parts of the heating curve?
What are the parts of the heating curve?
What are the parts of the heating curve?
What are the parts of the heating curve?
What are the parts of the heating curve?
Why is the curve flat at some portions?
Temperature is staying constant, but potential energy is decreasing
During this time the solid completely becomes liquid (or liquid becomes solid)
Why is the curve flat at some points?
This is called the heat of fusion (Hf) in segment BC and heat of vaporization (Hv) in segment DE.
Remember fusion is melting and vaporization is evaporation
What is heat of fusion? What is heat of vaporization? Hf is the amount of
energy needed to completely make a solid into a liquid
Hv is the amount of energy needed to completely make a liquid into a gas
Heating Curves Water heating curve
Cooling Curves Stearic cooling curves
Cooling curves have horizontal flat parts where the state changes from gas to liquid, or from liquid to solid
Stearic acid has a melting point of about 69°C - the temperature stays the same as the liquid freezes
Temperature Change What happens to the temperature of stearic acid as it freezes?
Your task is to measure the temperatures of the stearic acid as it cools every 30 seconds (as well as noting the state of the stearic acid (solid, liquid, gas)): -
Time (seconds) Temperature (oC) State (solid / liquid / gas)
0
30
60
90
120
Etc…
Temperature Change What happens to the temperature of a block of ice when a medium
constant heat is applied to it?
Your task is to measure the temperatures of the ice as it is heated every 30 seconds (as well as noting the state of the water (solid, liquid, gas)): -
Time (seconds) Temperature (oC) State (solid / liquid / gas)
0
30
60
90
120
Etc…
