User:Nadiezda Fernandez-Oropeza/Notebook/Notebook/2010/09/21: Difference between revisions

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Take the wax paper or the weighing boats from storage.Do it on such way that you would avoid the contact with the rest of the stoke as much as you can. Once they have been removed from the original container, they need to be used or discarded, they cannot be placed back once they are out.
Take the wax paper or the weighing boats from storage.Do it on such way that you would avoid the contact with the rest of the stoke as much as you can. Once they have been removed from the original container, they need to be used or discarded, they cannot be placed back once they are out.
* If you use wax paper, bend the paper in half to create a crack for a better placement of the sample.
* If you use wax paper, bend the paper in half to create a crack for a better placement of the sample.
[[Image:Waxpaper.jpg|thumb|center|Folding wax paper]]
* If you use the weighting boat, get rid of the possible left plastic strings on the edges. Then blow the base of the boat with air or nitrogen gas to make sure there are not plastic pieces left, since they could contaminate the sample.
* If you use the weighting boat, get rid of the possible left plastic strings on the edges. Then blow the base of the boat with air or nitrogen gas to make sure there are not plastic pieces left, since they could contaminate the sample.


Revision as of 10:20, 20 October 2010

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Basic Notes for working on a Laboratory

  • Some basic procedures when working on a chemistry lab.

Cleaning

For proper cleaning of the glassware, check Koch Lab protocols: General Lab Techniques. [Cleaning glassware protocol]

Important side notes:

  • If you are using a sponge to clean the lab items, do not use the coarse side of the sponge when cleaning things made out of metal.
  • Nitrogen gas is used to dry certain lab items.
  • For a proper removal of the plastic gloves, check the following website: [Proper glove removal]

Disposal of used acid and used base

Pour the excess of acid or base into a big beaker full of RUNING water. Let it flow until everything is dissolved.

  • Note: Water should be flowing for a considerable amount of time.

The concentrated acid or concentrated base is always added to water and not the other way round for two main reasons:

  1. This is an exothermic reaction. Thus, a lot of water is needed to absorb the heat generated. In other words, it is done to take advantage of the relatively high heat capacity of water.
  2. If water was added into acid, there is the risk of the acid splashing and reaching you. Adding the acid to the water cancels this risk off.

Gloves, wax weighting paper, and any other material that has or may have been in contact with the acid of base should be discarded in a properly designated waste bag.

How to properly weight a sample

First, make sure the scale is balanced or leveled. Do not make rough movement close to the balance, since it is very sensitive. Finally, try to keep the glass windows on the side of the balance closed, at least as much as you can.

To weight a sample, use either weighing (wax) paper or weighing boats.

Take the wax paper or the weighing boats from storage.Do it on such way that you would avoid the contact with the rest of the stoke as much as you can. Once they have been removed from the original container, they need to be used or discarded, they cannot be placed back once they are out.

  • If you use wax paper, bend the paper in half to create a crack for a better placement of the sample.
Folding wax paper
  • If you use the weighting boat, get rid of the possible left plastic strings on the edges. Then blow the base of the boat with air or nitrogen gas to make sure there are not plastic pieces left, since they could contaminate the sample.


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