Soxteaching: Physics, Chemistry, Technology

Purpose

The goal of this lab is to examine the spectra of different elements and determine the identity of an unknown substance

Procedure Notes

• using the spectrometer, record the spectrum for each element
• be as careful as possible in identifying prominent lines in each spectrum
• do the same for the unknown substance

Purpose

The goal of this lab is to verify Hess’s Law: if the sum of two chemical reactions is a third reaction then the sum of the two reaction enthalpies is the enthalpy of the third.

Procedure Notes [LINK]

• make sure that the calorimeter is clean and dry before each use
• do not contaminate the solutions with each other as that will distory the results
• any acid spill – neutralize with baking soda
• any base spill – neutralize with vinegar
• the smell of ammonia is powerful – be very careful and do not directly smell
• be sure and ask how to be coached on using the GLX to save files

You will be required to use a lab notebook throughout your course of study this year. This will serve as your lab and activity diary and is to be brought to class every day. Think of this as the place where all thinking associated with labs and activities will be recorded. While you should ensure that submitted work is neat and legible, much of the purpose of this book is to serve as your scratch paper as well. By the end of the year you will have a comprehensive record of all that you have accomplished in this course.  I will periodically collect and check your progress, although not every time that an activity is completed. Here are some things to keep in mind about your lab notebook.

• Every page should be numbered (in ink) in the upper-right corner
• Only use blue or black ink when writing in the lab notebook
• Mistakes should be crossed out – no erasing or white out
• Write only on the right side of the lab pages for entries you wish to submit
• All data collection, notes, ideas, processing must be shown in the notebook
• Label the front of the notebook with your name, class, period
• The first page is reserved for the table of contents, updated as entries are made
• No photocopies are allowed to be taped into the book, with the exception of graphs
• The top of the first page of every activity should have the proper labeling (date, topic etc)
• Even when working in groups, each person should have a copy of the collected data

Ugh – how I truly hate grading lab reports. To point, if there was one aspect of the course that I would put off until absolutely necessary it would be the evaluation of lab reporting. I am in the middle of trying something new this semester, students post lab results on a Tumblr blog, and this has been a mixed bag of results so far.

On the one hand, it had freed both the students and the teacher from the heinous process of overly-structured lab notebooks. Nothing kills a lab, and I mean NOTHING, like an ornate lab formal lab report. While the guidelines are clear they are infused with countless small details that are easily overlooked, especially by a student who has six other classes to attend. (As a side note: I am always startled by this fact when I think of it in the abstract, objective way that is detached from my insulated world.)

But it truly IS important to learn how to operate as a lab scientist and leaving this overt coaching out of the class process leads to such wide variation that reading whatever is posted becomes almost unbearable. Maybe the solution is to have a broad rubric which makes it easier to grade holistically. But what would that look like?

Data

• Data is anything directly recorded, including units, organized in a table
• No calculations or interpretations or conversions of any kind allowed

Friday, October 21 – Lab Notes

The lab explores two gas laws: Boyle’s Law and Gay-Lussac’s Law. The data collection devices will be used to collect pressure and temperature information which will then be used to verify each of the laws. In addition, the second experiment will be used to estimate absolute zero. [LAB INSTRUCTIONS]

The first lab is quite straightforward

• be sure and start with the volume in the tube at its largest for the lab. Each trial should be smaller.
• Be sure and get to the smallest volume possible as this is where you will see the greatest pressure differences

Friday, October 7 – Lab Notes

The lab is an example of calcualting the volume of a gas produced by a reaction [Instructions]. The reaction is quite simple as magnesium is reacting with hydrochloric acid, producing hydrogen gas. What if this gas was captured? IS it possible to use this as a way to determine the molar volume of a gas?

Obviously the answer is “yes” as this is what we will do. There are a few aspects to keep in mind when performing this lab.

• make sure the magnesium is the limiting reactant in this process so that it can predict the moles of hydrogen gas produced
• be sure and level the tube to the same level as the water outside of the tube, guaranteeing that the pressure of the gas inside the tube is the same as that outside the tube (atmospheric pressure)
• the temperature of the water is assumed to be the temperature of the gas, which is a great assumption given that the gas was produced and then bubbled through the water.
• the partial vapor pressure of water depends only upon the temperature of the water [LINK] and is to be subtracted from the total pressure of the gas to find the pressure of just the hydrogen
• once corrected, the molar volume of the gas is a simple “combined gas law” problem.