So here is your first lab assignment using Beyond Labz. Remember you can complete this while you are under the 5-day free trial.
Determine the Heat of Vaporization of Water using Clausius -Clapeyron relationship
In this simulation you will measure the vapor pressure of water at various temperatures. By plotting your data you will be able to estimate the heat of vaporization of water using the Clausius-Clapeyron equation.
We will discuss vapor pressure as part of Module 2 (see module 2: Intermolecular forces and Liquids). You can also read more about vapor pressure and the Clausius-Clapeyron equation in the 9th Ed Kotz textbook, Chapter 11 section 11-6 segments on Vapor Pressure and the Clausius-Clapeyron equation (pages 425 – 428).
In addition to access to Beyond Labz, you will need some skills with graphing and access to software for making graphs to complete this assignment (for example, Microsoft Excel). Some help will be given with this for Microsoft Excel.
Beyond Labz Instructions
Download the Beyond Labz worksheet for Heat of Vaporization of Water. 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 instead of looking in the Beyond Labz software.)
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 “Colligative Properties” and then select “Heat of Vaporization of Water”. The lab will then open.
Follow the instructions in the Heat of Vaporization of Water 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.
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.
For calculations in the worksheet show your calculation set up, not just the final answer.
To help you get started you can watch a short prelab demo of Beyond Labz that I made as a narrated powerpoint presentation or video
Graphing
In steps 4 and 5 of the worksheet you are directed to create a plot of the natural log of vapor pressure, Ln (P) as a function of the reciprocal of temperature in Kelvin (1/T). You need to determine the best linear fit for your data and use the slope of the line obtained from the best fit equation to calculate the heat of vaporization of water, Hvap, based on the knowledge from the Clausius-Clapeyron equation that
Hvap = -slope x R (where R is the Universal Gas Constant, 8.314 J.K-1.mol-1.
To facilitate this you can download this Excel_Graph_Template and enter your data to produce a plot with a linear fit drawn showing a linear fit equation. You need Microsoft Excel or an application that can use Microsoft Excel files to do this. (If you see a warning notice near the menus when you open this file in Excel, click the “Enable editing” button to allow you to modify the file).
You can also use your own software to accomplish this task. Make sure your graph contains the following:
- A title
- Axis titles for the X and Y axis
- Plot Ln (P) on the y-axis, 1/T on the x-axis
- Plot you data points
- Expand the scale so that your data fills the graph
- Include the best linear fit to your data (can be drawn by hand)
- Linear fit equation (if you draw the best fit line by hand you need to at least calculate the slope of this line)
To help with graphing you can watch a short demo that I made as a narrated powerpoint presentation or video
Preparing and submitting your work
When you are done you should have the completed worksheet and a completed graph.
For 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 of the table 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_Vapor” or “Lastname_FirstInitial_Molecules” replacing “Lastname” and “FirstInitial” with your own lastname and first initial (for example: Dutnall_R_Vapor.pdf).
For the graph, if you used the template file, save it with your name attached to the filename. You can submit this file directly.
If you produce your own graph, save it as a PDF format or take a picture and convert to PDF as described above.
When you are ready, click the “Submit Assignment” button at the top of this page and use the options available to upload your files for the worksheet and graph. Remember to click “Submit”. The due date is August 30th at 11:59 pm.
If you need help, or have not submitted an assignment in Canvas before, check out this assignments help video.
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