February 2011 Archives

Experiment 13

Hi everyone,

Lab 13 is quite a long one. Be aware!

Some tips to help the lab run more smoothly:


  • This lab has a waste treatment that takes some good amount of time. Tell them to make as less waste as possible so they'll finish on time. For example, tell them to use the well plate's lid to carry out the reactions (then they'll make less waste in first place).
  • If you tell them to use the lid they might end up having less than 15 drops for titration.I don't think it's a big deal as long as they count how many drops they are using.
  • The lab manual tells them to wait for 10 minutes between washes. They don't have to wait that long. They can go to the next step as soon as the white precipitate has settled down. 
  • I think it's a good idea to emphasize the 1:6 ratio between iodate and thiosulfate in your talk.
  • When they are adding the KI crystals to the solution they should use scoopulas not their hands!!! Also tell them that it's OK if the number of crystals aren't exact.
  • Remind them to use filter papers in their funnels! and I also think it's a good idea to show them how you fold a filter paper correctly.

That's all for now,

Have a good week

Experiment 12

Hi everyone,

These are the points that seem important for this lab:

  • Make sure you highlight that this week when setting up LoggerPro they should use Appendix G - "Collecting a complete spectrum"
  • Remind them that in all runs they use 5 mL of Fe(NO3)3
  • Emphasize that in Keq we use the equilibrium and not the initial concentrations. It is a good idea to go through the equilibrium concentration calculations (ICE table) in your prelab talk or individually
  • Don't forget to put up the beer's law equation on the board which you would find from the stockroom
  • Make sure they are using Excel correctly to make their spread-sheets. Some of them either don't understand the point of using Excel and start calculating and typing numbers in themselves and some just don't know how to use Excel.
  • Tell them to be careful about contaminating the solutions in part 2
  • Don't forget to pick up your evaluation forms from Nancy's office

That's all,

have fun with all the snow :)

Experiment 11 (Part 2)

Hi all,

This experiment went pretty smooth and fast.

Things to have in mind:

- It seems like all laptops have Office '10 on them now. So the part in the lab manual that speaks about the "chart wizard" confuses some of the students. Tell them to not pay attention to it unless they have an older version of Office installed.

- Tell them to be very careful with units specially units on the rate constant, frequency factor and activation energy.

- Emphasize that in the Arrhenius equation T actually stands for temperature and not time . Lots of them make that mistake.

- It is helpful to put up the equations for the integrated rate laws.

- Make sure they have the number to their datasets written down. That's what you need to grade them!


Nothing more,

Enjoy the great weather this week :)

Experiment 11 (Part1)

Hi everyone,
I hope you all had a great weekend :)
This week's lab is quite long.
Things to have in mind with this experiment:

- In the lab manual it tells them to run each experiment for 10 minutes. This is too
  long. Tell them to run each for 2-3 minutes.
- Remind them to select the 415 nm wavelength and unselect the other wavelengths.
- Make sure that when they are plotting their data in Excel they have "log Q" on the
  y-axis and not the x-axis.
- Encourage them to do their Excel graphs or at least the calculations neccesary for it
  in the lab, while you're around. They would learn better and it would save you time
  when grading.
- Tell them to calibrate their spectrometers with water before starting the runs.
- In your prelab talk try not to confuse them with too many details about the calculations.
  Keep reminding them that the goal is to find x,y and z (orders of reactants). Sometimes
  they really get lost.
- Maybe a good idea is to remind them when the "M1V1 = M2V2" formula is used.

That's all for now,

Have a good one !

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