Introduction to Laboratory Techniques
Introduction to Laboratory Techniques

Introduction to Laboratory Techniques

Lead Author(s): Julie Goll

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Laboratory Techniques for Synthesis.

Lab Safety

Protecting yourself in the lab:

In a chemistry synthesis laboratory most of the chemicals are toxic by inhalation, ingestion and skin absorption. Many of the chemicals used are also corrosive and flammable. It is necessary to take the proper pre-cautions at ALL times when you are in the lab.

EYES

Your eyes must be protected at all times in the lab, from the moment you enter the lab until you physically walk out the door (even when you are packing up your belongings!). There are two types of safety glasses available for this laboratory: regular safety glasses and special safety glasses made to go over eye glasses. If you wear glasses, then you will need to purchase the latter pair of safety glasses. 

IT IS REQUIRED THAT SAFETY GLASSES BE WORN IN THE LABORATORY WHENEVER YOU ARE PHYSICALLY IN THE LAB – NO EXCEPTIONS! 

FACE and LUNGS

All processes must be performed in a fume hood as much as possible. Exceptions are: using the balances, rotary evaporators or running analyses such as a melting point. The fume hood sash should never be raised such that the fume hood is operating below 100% since this means you are inhaling fumes from your reaction (defeating the purpose of the fume hood!!). The sash also protects your face from any splashes or splatters that may occur. If you have long hair, please ensure it is tied back and out of your face. This prevents your hair from contacting chemicals or open flames and keeps you path of vision clear.  

Any chemicals being transferred from one fume hood to another must be sealed with a glass stopper, cap or at minimum with your gloved hand. Do NOT place chemicals on the bench at any time. 

SKIN and FEET

Since many of the chemicals used in the lab are corrosive and can absorb through the skin, it is required that you wear a lab coat and gloves whenever conducting an experiment or handling chemicals in the lab. Lab coat sleeves should cover your forearms and lab coats should be buttoned up. It is also required that you wear closed-toe shoes in the lab to prevent chemicals or broken glass from getting on your feet or in between your toes. If possible, it is preferred that you wear pants to the lab.

In the unfortunate event that any chemical contacts your skin or eyes, you must flush with water immediately for at least 15 minutes.

Eye wash stations are located at each bench end, on the opposite side of the rotary evaporators. 

Other Hazards in the Chemistry Synthesis Lab:

FIRE AND EXPLOSIONS 

Fire is a major hazard in any chemistry laboratory. The vapours of nearly all organic solvents are flammable. To avoid igniting flammable vapours, keep open flames, electric sparks (flint lighters) and heating elements away from solvents and, where possible, prevent vapours from escaping containers by keeping caps and lids closed.

When using a heat gun to dry glassware ensure any organic solvents or paper towels are not in the vicinity of the heat gun as they can catch fire.

When using metal compounds, such as magnesium, ensure to avoid contact with acids.

Other fire safety suggestions are:

  1. Know the location of the nearest exits, fire extinguisher and fire alarm. 
  2. In case of fire or explosion, leave immediate vicinity. Pull nearest wall alarm. Do not return to area until fire department gives permission. 
  3. If clothing catches fire remember Stop, Drop and Roll. DO NOT RUN.
  4. Limit flammable liquids to amount needed for immediate use.
  5. Ensure flammable solvents are kept away from the hot plates.

FIRE EXTINGUISHERS 

Different types of fires require different methods of extinguishing them; in some cases the use of the wrong extinguisher can make the fire worse.

  • Electrical Fires, Chemical Fires or Flammable Liquid Fires: use fire extinguisher located at the front of the lab. DO NOT USE WATER.
  • Metal Fires (including Na, K, Mg, Al): sand, NaCl, dry soda ash, graphite. DO NOT USE WATER OR FIRE EXTINGUISHER. 
  • Wood, Paper, Textiles and Rubbish: Water unless it gets out of control, then use the fire extinguisher located at the front of the lab.

Note: if there is a small fire the easiest way to put it out is to remove oxygen by placing a large beaker over the fire.

If a fire extinguisher is used report it to the lab instructor immediately.

FIRE ALARM 

If the fire alarm sounds, turn off all gas, electricity, and water and leave the building by the exit indicated by your Lab Instructor. In STC you must exit immediately to the outside of the building. You will not be allowed to enter an adjoining building when the fire alarm sounds.

HANDLING GLASSWARE

Laboratory glassware is fragile, and many unnecessary accidents have occurred because of improper handling. 

  1. When inserting glass or porcelain into a rubber stopper or rubber filter adaptor, gently twist while applying pressure. When removing, gently twist and pull. 
  2. When applying tubing to glass joints gently twist the tubing on. To assist with this, you can lubricate the water condenser inlet and outlet with water or acetone first. To remove, gently twist the tubing off. 
  3. Broken glass should be cleaned up with a brush and dustpan. Never use your hands or paper towels to clean up broken glass. 

When in doubt get a TA or the Instructor to help you.

HANDLING CHEMICALS

  • If diluting acid always pour acid into water while agitating. NEVER POUR WATER INTO ACID
  • NEVER return unused chemicals to stock bottles. Excess solids can be disposed of into the solid waste container (unless they have a separate waste container specified, i.e. Mg); excess organic liquids can be disposed of into the yellow waste container; excess aqueous solutions can be disposed of into the black waste container or down the drain where specified.
  • All chemicals and disposable items in the organic laboratory have a specific waste container. This information is included in the procedure. All waste must be disposed of properly, if you are unsure, please ask. 
  • Aqueous waste is either acidic or neutral. Basic aqueous waste must be neutralized with acid before being disposed. Please refer to your waste instructions in each experiment.
  • Unlabelled chemicals must not be used. 
  • All spills must be cleaned up immediately and the instructor must be notified. 
  • A direct flame or heat gun must never be used to heat liquids in this lab. A hot plate is to be used for direct or indirect heating (i.e. a water bath). 
  • Neutralize acid or base (clothing, desktop or floor) by washing with plenty of water. Solid sodium bicarbonate may be used to neutralize large amounts of either acid or base. 
  • Chemicals are, in general, expensive. An estimation of the quantity required should be made at the beginning of each experiment. 

Give strict attention to all instructions and if you are unsure, check with the instructor before undertaking an experiment. 

Safety Question 1

Which of the following statements is correct regarding laboratory safety in the Lab? (Select all that apply)

A

All glass waste including Pasteur pipettes and melting point capillaries must be disposed of into a glass waste container and NOT the solid waste.

B

When diluting acid slowly add the water to acid with agitation.

C

Many chemicals used the lab are corrosive and can absorb through the skin therfore wearing a lab coat and gloves is required whenever handling chemicals.

D

When using a fume hood the fume hood sash can be as high as needed.

Safety Question 2

Which of the following statements is correct regarding laboratory safety in the lab? Select all that apply.

A

When applying tubing to glass joints it helps to lubricate the glass with water or acetone.

B

Broken glass should be disposed of into the solid waste container.

C

If excess solid chemicals are weighed out they should be disposed of into the solid waste or other appropriate waste container.

D

If a chemical is spilled mop it up with paper towels and dispose of them in the garbage.

E

Pasteur pipettes and melting point capillaries are considered glass waste.

Safety Question 3

If the fire alarm sounds, which of the following must be turned off? Select all that apply.

A

Water

B

Gas

C

Electricity

D

Air

Safety Question 4

Which of the following statements is correct regarding laboratory safety in the lab? Select all that apply.

A

All chemicals should be kept in a fume hood at all times. Some exceptions are weighing out a solid or running a melting point.

B

Heat guns can be used to dry glassware but can ignite organic solvents and paper towels.

C

Safety goggles are not preferred since they tend to fog up.

D

You may remove your safety glasses once you complete the experiment and are no longer handling any chemicals.

Safety Question 5

Which of the following statements is correct regarding laboratory safety in the lab? Select all that apply.

A

When used properly the fume hood prevents the inhalation of fumes from chemicals used.

B

In the synthesis lab most chemicals are not flammable.

C

If excess solid chemicals are measured out they can be returned to the stock bottle.

D

In an organic chemistry lab most chemicals are toxic by inhalation or ingestion or skin absorption.

E

Broken or disposable glass can go into the solid waste container.