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Unit 5: A Thermodynamic Model of Chemical Change Notebook Labs

View Scoring Rubrics (link coming soon)

The following items should be in the Unit 5 portion of your notebook.  They should be clearly organized and easy to find.  Use an organizational system and label all work. Each lab will be graded separately.  All lab grades will be entered into the gradebook.


Lab T1 - Zero in On Heat

Question:
How can the temperature changes experienced by two objects in close contact with one another be described and explained?

Purpose:
To describe and explain the temperature changes experienced by two objects of different temperature when placed in close contact with one another.

Safety:
Be cautious of burns from exposure to the hot water.  Avoid laying face down in the water for several minutes; results can be fatal.

Disposal:
The water can be poured down the drain.

A complete lab write-up includes a Title, a Purpose section, a Data section, and a Conclusion/Discussion section.  The Data section should include a table of time and temperature data for the two reservoirs of water and a well-labeled plot of both sets of data on the same graph (provided). The Conclusion/Discussion should describe how the temperature changes over time for both sets of data.  A thorough explanation based on the zeroeth law of thermodynamics should be given.





Lab T2 - Specific Heat Capacity of a Metal

Question:
What is the specific heat capacity of a sample of metal?

Purpose:
To determine the specific heat capacity of a sample of metal.

Safety:
Wear goggles at all times.  Exercise caution when working with a hot plate.  Use tongs when handling hot glassware and metals.  Remember that the hot beaker and the cold beaker look the same.

Disposal:
Clean and organize your station when you are finished.  Return the metal sampel to its original location.

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should include an organized and labeled listing of data;  labels should be informative and units should be stated.  The Data section should also show calculations used to determine the specific heat capacity of the metal;  each step of the calculations should be clearly labeled and annotated to indicate what is being calculated.  The theoretical value of c should be stated and a percent error calculation should be performed.  The Conclusion should answer the question posed in the Purpose of the lab.  The Discussion of Results should included an error analysis in which you respond to the question How well did we do?  The percent error should be discussed and specific sources of error should be identified and explained.





Lab T3 - Heat of Fusion

Question:
What is the molar heat of fusion of ice?

Purpose:
To determine the molar heat of fusion of ice (on a kJ/mol basis).

Safety:
Wear goggles at all times.  Exercise caution when working with a hot plate.  Use tongs when handling hot glassware.  Remember that the hot beaker and the cold beaker look the same.

Disposal:
Clean and organize your station when you are finished. Pour the water down the drain and rinse your glassware.

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should include an organized and labeled listing of data;  labels should be informative and units should be stated.  The Data section should also show calculations used to determine the molar heat of fusion;  each step of the calculations should be clearly labeled and annotated to indicate what is being calculated.  The theoretical value of the heat of fusion should be stated and a percent error calculation should be performed.  The Conclusion should answer the question posed in the Purpose of the lab.  The Discussion of Results should included an error analysis in which you respond to the question How well did we do?  The percent error should be discussed and specific sources of error should be identified and explained.





Lab T4 - Heat of Solution

Question:
What is the molar heat of solution of mmonium nitrate?

Purpose:
To determine the molar heat of solution of ammonium nitrate.

Safety:
Wear goggles at all times.  Exercise caution when working with hot beakers.

Disposal:
The solutions can be poured down the drain and rinsed thoroughly.  Undissolved solids should be poured into the garbage can. Wipe your lab station down when finished.

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should organized and labeled;  labels should be informative and units should be stated.  The Data section should also show calculations used to determine the molar heat of solution;  each step of the calculations should be clearly labeled and/or annotated to indicate what is being calculated; work should be shown.  The theoretical value of the heat of solution for ammonium nitrate should be stated and a percent error calculation should be performed.  The Conclusion should answer the question posed in the Purpose of the lab.  The Discussion of Results should include an error analysis in which you respond to the question How well did we do?  The percent error should be discussed and specific sources of error should be identified and explained.





Lab T5 - Heat of Combustion

Question:
What is the molar heat of combustion of candle wax (paraffin - C25H52)?

Purpose:
To determine the molar heat of combustion of candle wax (paraffin - C25H52).

Safety:
Wear goggles at all times.  Exercise caution when working with flames and hot melted wax.  Return the candle to its original location.

Disposal:
Clean up and organize your lab station when finished. Return the candle to its original location. Pour water down the drain (a quite obvious location for it).

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should include a table with labeled column headings and rows which organizes the collected data;  labels should be informative and units should be stated.  The Data section should also show calculations used to determine the molar heat of combustion of paraffin;  each step of the calculations should be clearly labeled and annotated to indicate what is being calculated.  The theoretical value of the heat of combustion of paraffin should be stated and a percent error calculation should be performed.  The Conclusion should answer the question posed in the Purpose of the lab.  The Discussion of Results should include an error analysis in which you respond to the question How well did we do?  The percent error should be discussed and specific sources of error should be identified and explained.







Lab T6 - Heat of Formation

Question:
What is the heat of reaction for the reaction of Ca metal with water? What is the heat of formation of calcium hydroxide?

Purpose:
To use calorimetery to determine the heat of reaction for Ca metal reacting with water and to calculate the heat of formation of calcium hydroxide (knowing that the heat of formation of H2O(l) is -286 kJ).

Safety:
Wear googles at all times.  Calcium is extremely reactive; avoid contact with skin.  Hydrogen gas is produced; keep away from flames.

Disposal:
The final solution should be poured down the drain and rinsed with plenty of water.

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should include a table with labeled column headings and rows which organizes the collected data;  labels should be informative and units should be stated.  The Data section should also show calculations used to determine the heat of reaction for the studied reaction. These calculations should be clearly organized, follow-able, labeled, and give attention to units and significant digits. Finally, the heat of raction value should be used to determine the heat of formation of Ca(OH)2;  these calculations must include a balanced chemical equation for the reaction, the equation relating heat of reaction to heats of formation values for the reactants and products, and several lines of algebraic manipulation;  each step of the final process MUST be briefly annotated to indicate the logic of that step.  The theoretical value for the heat of formation ofCa(OH) 2 (-890 kJ/mol) should be listed and used to calculate the percent error; work should be shown. The Conclusion should answer the question posed in the Purpose of the lab.  The Discussion of Results should include an error analysis in which you respond to the question How well did we do?  The percent error should be discussed and specific sources of error should be identified and explained.







Lab T7 - A Nutty Experience in Thermochemistry

Question:
What is the heat content of a nut in units of kJ/gram?

Purpose:
To determine the heat content of a nut in units of kJ/gram.

Safety:
Wear goggles at all times.  Exercise caution when working with flames and hot objects.  Food (including nuts) should not be eaten in chemistry class without the teacher's permission (which is rare).

Disposal:
Clean up and organize your lab station when finished. What remains of the nut can be placed in the garbage can.

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should include a table with labeled column headings and rows which organizes the collected data;  labels should be informative and units should be stated.  The Data section should also show calculations used to determine the molar heat of combustion of paraffin;  each step of the calculations should be clearly labeled and annotated to indicate what is being calculated.  The Conclusion should answer the question posed in the Purpose of the lab.  The Discussion of Results should include a discussion of specific sources of error; sources should be identified and explained.







Lab T8 - Hess's Law

Question:
What is the heat of reaction (∆H) for the reaction: Mg(s) + 1/2 O2(g) ==> MgO(s) ?

Purpose:
To use Hess's Law and calorimetry measurements to determine the enthalpy change or heat of reaction for the reaction: Mg(s) + 1/2 O2(g) ==> MgO(s)

(Given:  the ∆H for the reaction H2(g) + 1/2 O2(g) ==> H2O(l) is -285.8 kJ.)

View Procedure.


Safety:
Hydrochloric acid is toxic by ingestion and inhalation;  it is corrosive to skin, eyes and clothing.  Magnesium metal is extremely flammable;  keep away from flames.  Wear goggles at all times.

Disposal:
Unreacted solids (of which there should be none) should never be placed in the drain.  All other solutions can be poured down the drain and rinsed thoroughly.

A complete lab write-up includes a Title, a Purpose section, a Data section, a Conclusion, and a Discussion section.  The Data section should include five sections.  There should be two sections with  organized and labeled data tables of measured quantities for the two parts of the experiment. The Data section should also include two lengthy and organized sections of calculations in which the enthalpy changes are determined for the two different reactions;  work should be shown labeled and annotated.  Finally, the Data section should include an organized section in which the heat of reaction (∆H) for the target reaction is calculated from the determined values for the two reactions and for the given reaction.The theoretical value should be listed and the percent error should be calculated. The Conclusion should include a single section in which the answer to the given question is stated.  The Discussion of Results should include an error analysis in which you respond to the question How well did we do?  The percent error should be discussed and specific sources of error should be identified and explained.





Lab T9 - Heating Curve

Question:
What happens as a sample of ice is heated past its freezing point to its boiling temperature?

Purpose:
To construct a plot of the heating curve of water and to interpret the results.

Safety:
Wear goggles at all times. Exercise caution when working around a hot plate or burner.

Disposal:
The water can (of course) be poured down the drain.  Turn off your burner and tidy up your lab station.

A complete lab write-up includes a Title, a Purpose section, a Data section, and a Conclusion/Discussion section.  The Data section should include a table of collected data with column headings and units for the heating of ice and a computer-generated plot with labeled axes.  The Conclusion/Discussion should address the provided questions (below).  The discussion should not just be an enumerated list of answers to questions, but instead should be a fluent discussion of the lab results which in turn respond to the questions.

The Questions:
1. Observe the plateaus on the graph.  What could be happening during these plateaus?
2. Based on your data and observations, what is the melting point and the boiling point of water?
3. Describe what happens at the particle level as heat is added to a substance and its temperature increases.
4. Describe what happens at the particle level as heat is added to a substance and its phase changes.






Lab T10 - Heating and Cooling Curve

Question:
What happens as a solid is heated to and past its melting point?  What happens as a liquid is cooled to and past its freezing point?

Purpose:
To construct a plot of the heating and cooling curves of lauric acid and to interpret the results.

Safety:
This lab uses provided data.  There are no safety issues.

Disposal:
None

A complete lab write-up includes a Title, a Purpose section, a Data section, and a Conclusion/Discussion section.  The Data section should include the provided data (taped in) for the heating and cooling of lauric acid and two computer-generated plots with labeled axes.  The Conclusion/Discussion should address the provided questions (below).  The discussion should not just be an enumerated list of answers to questions, but instead should be a fluent discussion of the lab results which in turn respond to the questions.

The Questions:
1. Observe the plateaus on the two graphs.  What could be happening during these plateaus?
2. Determine the melting point and freezing point of lauric acid.  How do they compare?
3. Describe what happens at the particle level as heat is added to a substance and its temperature increases.
4. Describe what happens at the particle level as heat is added to a substance and its phase changes.












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