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SUMMER INSTITUTE – Module 4 – Energy – Phase Changes

DUE by (or on) by July 26th
***By the way we are entering the 7th week of the 1st quarter of Regents Chemistry
 
5 Hours
 
Module 4 Notes pg 21-24.pdf
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*Connections – We have learned that phase changes (melting, freezing, boiling, condensation, sublimation, deposition) physical processes but energy changes are still associated with them.  We should now know which energy changes are now endothermic as well exothermic.  
 
Example: Gases have the most energy so going to a gas means it must be endothermic change and energy is thus absorbed (or better yet consumed).  
 
We have not considered the energy changes in phase changes that occur in calorimetry problems because there are no  temperature changes in when a phase change occurs.
 

Energy – intro

 
 
 

Activity 1:  SKILL :  Observe a heating Curve and identify the phase changes, melting points, boiling points, potential energy, kinetic energy and all points on the graph. 
 
Notes: page 21 – 24
Energy Presentation: slide 22,23 and 24.
 
 
1: Please view presentation slides 22, 23, and 24.  Play all animations and videos.
 
2: View the time lapse video of the heating curve of water that was initially at about -40 degree Celsius.  
     ( I froze water with liquid nitrogen with a temperature probe embedded into the ice)
    – When you view notice what happens when melting begins.
 
     -When you view notice what happens when boiling begins.
3:  Please view the Ice melting Animation:
 
Ice melting animation (please come and join me inside the ice crystal as it begins to melt)-
 

 

Notice that the water molecules are initially in the solid phase, which is a 3 dimensional geometric pattern (crystal formation). They are initially vibrating in their fixed positions very slowly (low temperature) and as they absorb kinetic energy (heat) their vibration increases.  The vibrations increase up until the molecules start pulling away from each other(melting). Why would the temperature stay constant at this point.

                
4:  Please view the lecture on Heating and Cooling Curves:
5:  Please complete the worksheet and review with the key.
Heating and Cooling Curve Review worksheet.pdf
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Heating and Cooling Curve Review worksheet KEY.pdf
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This was the whiteboards of my regents students a few years ago. Their task was to draw models of a compound that was in three states of matter.
 
Notice: Solids must be in 3 dimensions arrangement; crystals
              Liquids have no definite shape (they take the shape of the container), but have a definite volume.
              Gases have no definite shape or volume (they always fill their container).
Demos:
-Sublimation – Phase change of a Solid that directly changes into a Gas
example – Dry Ice –  CO2(s)  –> CO2(g)   – Its dry because it skips the liquid stage. We will learn why.
 
-Deposition – Phase change of a Gas that directly changes into a Solid.
H2O (g)  –> H2O (s)  –  Water gas moving into a solid phase directly – SNOW!!!!!
This is an important demo! – 
Because of the fact that gas has no other phase to transition into, it has no limit in its
potential or how hot it become.

Activity 2:  SKILL :  Applying Heating and Cooling Curves to a Laboratory Assignment
                                                    Determine the identity of a substance by their melting points determined by plotting their heating 
                                                    and cooling curves.
 
1:  Please download and print lab below and follow along with me in completing the virtual lab.
      You will need to also download the data files that were collected by the temperature probes in     
      the lab.
 
LAB 5 honors -Cooling curves of an unknown substance.pdf
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Cooling Curve Virtual lab Data Curve.pdf
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Data Table Virtual lab.pdf
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2:  You can skip the Data Section (which is just questions on general heating and cooling curves) but complete Objective Page, Conclusion questions and Conclusion.  Please also attach copy of graph and the page of temperatures that has your freezing or melting point identified (as per video instructions).
 
3: Please keep this completed lab (minus the data questions).
      I will physically collect all labs in September.

 


Activity 3:  SKILL :   Heat of Fusion and Heat of Vaporization Problems

                        Identify Heat of Fusion (Hf) and Heat of Vaporization (Hv) on Heating Curve and learn to calculate                              heat with these constants when there is no change in temperature.
 
*Connection – At this point we have measured heat using q = mass x Specific Heat x Change in Temp but this will not work during a phase change because temperature stays constant thus we need another formula when we measure energy at phase changes.
 
1: Please view lecture 1.15B below that teaches the concepts of Hf and Hv and how to calculate the energy changes that occur at phase changes. Please follow along with the video using the worksheet below.  I will be modeling problems after I teach the concept in the lecture.  Feel free to stop the video and then do the problem when you start understanding how these problems work.
 
HV&HF problems honors .pdf
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HV&HF problems honors KEY .pdf
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Lecture 1.15B:
 

 

2:  Please review the lecture below that reviews the last question in the HV &HF problems honors .pdf worksheet that is an advanced question.  I explain how you set it up. It should look very familiar with the other advanced question in the last module, except it has a phase change wrinkle. 
Complete the problem and review with key posted below:
 
I have posted the question 9 in a full page worksheet that is in the lecture.
 
HV&HF problems honors2 .pdf
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HV&HF problems honors2 key.pdf
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Activity 4:  SKILL :  Determine the Heat of Fusion of Water – Lab
                                                    Experimentally determine the Hf for water – Endothermic Calorimetry.
1: Please view the Virtual Lab which is a calorimetry lab that determines the Hf of water.
Use the file below with the video to complete it.   I will physically collect all labs in September.

LAB 6 honors heat of fusion.pdf
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Module 4 Test –

 
Please complete the test below and enter into the auto-reply form below:
 
 
Module 4 Test.pdf
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Module Test 4 Form – Institute