I’m trying to study for my Chemistry course and I need some help to understand this question.
Beyond Labz Hess’s Law
In this simulation you will use coffee cup calorimetry to measure the heat of reaction (
Hrxn) for three reactions and show how they are related by Hess’s Law. This lab might take a little longer because you have to record data for three different reactions but the procedure for each is very similar to the lab simulations you have done previously.
As a basis for understanding this lab you should read Chapter 5, section 5-6 (calorimetry) and section 5-7 (Hess’s Law). You can also refer to Module 5 section on Calorimetry: Measuring Enthalpy Changes and Internal Energy Changes and the section on Measuring Enthalpy Change: Hess’s Law
Beyond Labz Instructions
Download the. Print this worksheet so that you can follow the directions on what to do, fill it in and submit it. (Please use this worksheet from Canvas as it contains several modifications from the Beyond Labz version)
Now launch the Beyond Labz software, and open the Chemistry Lab.
To launch the simulation look at the list of worksheets on the bottom left of the window. Click “Thermodynamics” and then select “Hess’s Law”. The lab will then open.
Follow the instructions in the worksheet. It is a good idea to read through the entire worksheet first before you begin so that you are aware of what is expected. Also check the notes on worksheet and calculations below.
As you progress through the simulation, fill in data and observations on the worksheet in blue or black ink. No pencil! Even though this is a virtual lab this is good lab practice and also important to make sure your submitted work will be clear enough to grade.
I think you have done enough of these Beyond Labz simulations by now, and especially calorimetry simulations, that you should be familiar enough with the software and the technique to do this lab without a prelab demo. Just remember to follow the instructions in the worksheet carefully.
Notes on worksheet and calculations
- Follow the instructions carefully to select the correct reactions for analysis
- Show your work for each calculation and pay careful attention to significant figures for full credit.
- Do not apply significant figures until the final step in your calculations (step 15). To avoid rounding errors, carry more sig. figs. in steps prior to this and then consider sig. fig. rules for each step as you consider the precision of your final answer.
- Remember to pay careful attention to the sign of calculations. Remember qrxn + qsolution = 0 and you calculate qrxn based on measuring what happens to the solution (qsolution).
- Remember that for a coffee cup calorimeter you are measuring qp, the heat transfer at constant pressure, where
ΔH =qp. So the qrxn you calculate is
ΔHrxn but needs to be converted to kJ/mol.
- In step 11 you need to calculate the mass of reaction solution for each reaction. Reactions 1 and 2 involve a solid reactant and an aqueous reactant. The mass of the solution is the mass of the solid plus the mass of the aqueous liquid (calculated from volume and density). Reaction 3 involves reactants that are both aqueous. The mass of the solution is therefore calculated from total volume of solution using density.
Preparing and submitting your work
After you complete the worksheet, take a picture of each completed page or scan them. Make sure the quality is good enough to view clearly. If I cannot read it, I will not grade it.
It is best to submit as a PDF or .jpeg (jpg) file. You can submit one file for each page or combine them into one file.
It is best if you submit one file for each simulation.
Check out free PDF Converter (Links to an external site.) and free PDF Merge (Links to an external site.) tools to convert photos to PDF and combine multiple PDF into one file. SmallPDF (Links to an external site.) also has other free tools for working with PDF files.
Please name your file for submission using the convention “Lastname_FirstInitial_HessLaw” replacing “Lastname” and “FirstInitial” with your own lastname and first initial (for example: Dutnall_R_HessLaw.pdf).
When you are ready, click the “Submit Assignment” button at the top of this page and use the options available to upload your file(s). Remember to click “Submit”. The due date is October 4th at 11:59 pm.
If you need help, or have not submitted an assignment in Canvas before, check out this assignments help video.