Good Laboratory Prac-ces
Science
labs, whether at universi2es or in your home, are places of adventure and discovery.
One
of the first things scien2sts learn is how exci2ng experiments can be. However, they must also realize science can be dangerous without some instruc2on on good laboratory prac2ces.
Read
the protocol thoroughly before star2ng any new experiment. You should be familiar with the ac2on required every step of the way.
Keep
all work spaces free from cluEer and dirty dishes.
Read
the labels on all chemicals, and note the chemical safety ra2ng on each container. Read all Material Safety
Data
Sheets (MSDS) prior to each experiment. These are provided on www.eScienceLabs.com.
Thoroughly
rinse labware (test tubes, beakers, etc.) between experiments. To do so, wash with a soap and hot water solu2on using a boEle brush to scrub. Rinse completely at least four 2mes. Let air dry.
Use
a new pipeEe for each chemical dispensed.
Wipe
up any chemical spills immediately. Check MSDSs for special handling instruc2ons (provided on www.eScienceLabs.com). An underpad will prevent any spilled liquids from contamina6ng the surface you work on.

Use test tube caps or stoppers to cover test tubes when shaking or mixing – not your finger! Special measuring tools in make experimenta6on easier and more accurate in the lab. A shows a beaker, B graduated cylinders, and C test tubes in a test tube rack.

Disposable pipeBes aid in accurate measuring of small volumes of liquids.
It
is important to use a new pipet for each chemical to avoid contamina6on. When preparing a solu2on, refer to a protocol for any specific instruc2ons on prepara2on. Weigh out the desired amount of chemicals, and transfer to a beaker or graduated cylinder. Add LESS than the required amount of water. Swirl or s2r to dissolve the chemical (you can also pour the solu2on back and forth between two test tubes), and once dissolved, transfer to a graduated cylinder and add the required amount of liquid to achieve the final volume.
A
molar (M) solu2on is one in which one liter (L) of solu2on contains the number of grams equal to its molecular weight. Ex:

1 M = 110 g CaCl ÷ 1 L

(The formula weight of CaCl is 110 g/mol)
A
percent solu2on can be prepared by percentage of weight of chemical to 100 mL of solvent (w/ v) , or volume of chemical in 100ml of solvent (v/v).
Ex:

20 g NaCl ÷ 80 mL H2O = 20% w/v NaCl solu-on
Concentrated
solu2ons, such as 10X, or ten 2mes the normal strength, are diluted such that the final concentra2on of the solu2on is 1X.
Ex:

To make a 100 mL solu-on of 1X TBE from a 10X solu-on:

10 mL 10X TBE ÷ 90 mL water = 100 mL