Embedded Files
Thermochemistry
Thermochemistry
Learning Objectives:
Learning Objectives:
Upon completion of this experiment, students will:
(CLO1). Explain basic chemical concepts related to chemical changes, energy, and properties of matter.
(CLO2). Apply the methods of scientific inquiry
(CLO4). Interpret and utilize mathematical formulas while solving problems
(MLO) Perform calorimetry calculations involving specific heat or heat capacity to determine the specific heat capacity of a calorimeter, known and unknown metal and a neutralization reaction.
(MLO) Use Hess's law, enthalpies of formation and bond energies to calculate heats of reactions or perform energy calculations that accompany reactions.
Experiment 14 discusses heat capacity, specific heat capacity and the technique of Calorimetry using a simulation.
The assignments that must be completed are:
The assignments that must be completed are:
Complete the pre laboratory problems before the laboratory session
Use the links below to perform the laboratory assignment virtually. Complete all calculations and questions in the Laboratory Report.
Discussion
Discussion
Every reaction results in a transfer of energy between the reactants and the products of the reaction. The energy can be measured with three thermodynamic quantities: ΔH, enthalpy, the heat of the reaction; ΔS, entropy, the disorder of the reaction; and ΔG, the total energy of the system or reaction. These quantities allow us to determine if the reaction is likely to occur or will most likely never occur without help. We talk about the spontaneity of a reaction as to whether the reaction occurs or does not. To understand this property, we must first be able to measure the thermodynamic properties; how this is done is the purpose of the experiment. If the overall energy of the system is decreasing, the energy is leaving the system to be absorbed by the surroundings, this is considered to be an exothermic or exogamic reaction and is given a negative value fo the loss; while the opposite situation in which the overall energy of the system is increasing, is called endothermic or endogenic, a positive value for gain. The question then is how do we determine if the system is loosing or gaining energy. The amount of heat that is lost by the system must be EQUAL to the amount of heat gained by the surroundings. In an isolated system, we can control the system and the surroundings by insulating the surroundings to be a small space surrounding the reaction. By doing do we can determine the amount of energy that is lost by the system by how much is gained by the surroundings.
The transfer of energy or heat is measured generally by the change in temperature. Temperature is NOT heat but they can be related by the specific heat of the substance, s. The specific heat is a physical property of substances that describes the ability to absorb or transfer heat. Specific heat is defined as the amount of heat or energy required to raise the temperature of one gram of the substance one degree Celsius.
If we rearrange this definition, then the energy is proportional to the mass of the substance and the temperature. The energy or heat is equal to
q = msΔT
q = msΔT
where q is the heat in Joules or calories, m is mass in grams, c is the specific heat and ΔT = the final temperature of the system minus the initial temperature of the system.
The enthalpy, ΔH, can be related to the heat, q, under specific conditions of pressure, where ΔH = m CpΔT, where Cp is defined as the molar specific heat or the amount of heat required to raise a MOLE of the substance one degree Celsius, thereby, giving ΔH the units of Joules per mole or kiloJoules per mole.
ChemDoctor: heat capacity of a coffee cup calorimeter
ChemDoctor: heat capacity of a coffee cup calorimeter
This video teaches the viewer how to calculate the heat capacity of a coffee cup calorimeter. More videos can be found at www.chemdoctor.org.
Pre Writing assignment
Pre Writing assignment
There is no required pre laboratory writing assignment.
Pre laboratory assignment
Pre laboratory assignment
The pre laboratory problems are questions about the laboratory assignment, background, definitions or procedure and calculations. Complete this assignment as part of the grade of the final laboratory assignment.
Procedure and Report
Procedure and Report
We will perform three parts of this experiment using the simulation of a bomb calorimeter below. The laboratory report of the assignment contains questions, data collection, calculation and reporting of results. Complete this assignment using the data collected in the lab or with the simulation as part of the grade of the final laboratory assignment.
Use the simulation below to complete the laboratory assignment.
Use the simulation below to complete the laboratory assignment.
Calorimetry Computer Simulation New HTML5 Version
This is open a page if you click on the tab: Experiment and then Run Experiment, you should see the above image. Follow the directions in the lab assignment to complete the three parts of the experiment.
older version: https://media.pearsoncmg.com/bc/bc_0media_chem/chem_sim/calorimetry/Calor.php
©2016 Greenbowe, Abraham, Gelder Chemistry Education Instructional Resources.
University of Oregon, Oklahoma State University, University of Oklahoma, Pearson
If you click on the second link, scan down and you will see the first link.
Part A: Heat Transfer of Cold and Hot water
Part A: Heat Transfer of Cold and Hot water
Use the simulation above to determine the heat gained and lost by water. In the simulation the heat lost by the warm water will equal the heat gained by the cool water. Run the simulation twice.
In real life the heat lost by the warm water will not be exactly equal to the head gained by the cooler water. The rest of the surrounding, including the calorimeter will also gain heat. Therefore, we can determine the heat capacity of a styrofoam coffee cup. Using warm and room temperature water, we will determine the heat lost by the warm water which will be equal to heat gained by the cooler water plus the heat gained by the calorimeter.
Part B: Specific Heat of a known metal and unknown Metal samples
Part B: Specific Heat of a known metal and unknown Metal samples
The second part of this experiment will use the calorimeter in an experiment where a metal that has been heated is added to water in the calorimeter. The heat lost by the hot metal will equal the heat gained by the cooler water plus the heat gained by the calorimeter. If we assume the heat capacity of the calorimeter is zero in the simulation above, we can determine the heat capacity of a known metal sample and an unknown metal. The unknown metal can be identified from it's heat capacity. Run two samples of the same known metal and two samples of the same unknown metal.
Heat Capacity, Specific Heat and Calorimetry
Heat Capacity, Specific Heat and Calorimetry
Professor Dave Explains - We can use coffee cups to do simple experiments to figure out how quickly different materials heat up and cool down. It's called calorimetry. Take a look!
Specific Heat of a Metal by Calorimetry
Specific Heat of a Metal by Calorimetry
Step by Step Science - Shows how to calculate the specific heat of a metal (or any material for that matter) by calorimetry.
Part C: Enthalpy of Neutralization
Part C: Enthalpy of Neutralization
The third part of this experiment is to determine the Enthalpy of an acid base reaction. A base, NaOH is added to an acid, either HCl or HNO3. The heat lost by the reaction is equal to the heat gained by the salt solution and the heat gained by the calorimeter. In the simulation, the heat of the calorimeter is again assumed to be zero. Therefore, the heat gained by the salt solution is equal to the heat lost by the neutralization reaction, q. This heat is then used to determine the enthalpy of the reaction in kJ ./ mol of water formed. We will run the reaction twice, first adding the acid solution to the base solution and the second run is adding the base solution to the acid solution. We will compare the enthalpy of the reaction calculated to the book value determined using Enthalpy of formations for the compounds in the chemical reaction.
Calorimetry: Enthalpy of Neutralization Reactions
Calorimetry: Enthalpy of Neutralization Reactions
Dr. Carolynn Arpin -
Dahlia and Joshua take you through the enthalpy determination for a couple of acid-base reactions in a calorimeter.
Calorimetry Calculations
Tom Iwanowski -
6th in a series of 9 films covering the SL Energetics topic from the IB Diploma chemistry course. Here we put into practice the formula used to calculate heat and enthalpy changes from measured temperature changes, and figure out the molar enthalpy of neutralisation.
Calculating Enthalpy Change of Reaction by Calorimetry
Calculating Enthalpy Change of Reaction by Calorimetry
MaChemGuy -
Explanation of Calorimetry method followed by two worked examples. Although this is a different reaction, the method and calculations are basically the same.
Post Laboratory Problems and Conclusion paragraph
Post Laboratory Problems and Conclusion paragraph
There are no post laboratory problems or conclusion paragraph for this laboratory assignment.
Report abuse