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| Joining
and Separating glass apparatus |
1. |
When storing
glass stopcocks and joints, insert a thin strip
of paper between joint surfaces to prevent sticking. |
2. |
Never store stopcocks for
long periods with lubricant still on the ground
surfaces. |
3. |
Glass stopcocks on Burettes
and Separation Funnels should be lubricated frequently
to prevent sticking. |
4. |
If a ground joint sticks,
separation can generally be achieved by carefully
racking the cone in the socket, or gently tapping
of the socket flange on a wooden surface, or by
heating the socket and not the cone in a localised
flame. The use of penetrating oil will often prove
useful in aiding separation. |
5. |
In using lubricants it is
advisable to apply light coat of grease completely
around the upper part of the joint. Use only a
small amount and avoid greasing that part of the
joint which contacts the inner part of apparatus.
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6. |
Three type of lubricants
are commonly use on standard taper joints
(A) Hydrocarbon grease is the most widely used.
It can be easily remove by most laboratory solvents,
including acetone.
(B) Because hydrocarbon grease is so easily removable,
silicon grease is often preferred for higher temperature
or high vacuum applications. It can be removed
readily with chloroform.
(C) For long term reflux or extraction reactions,
a water soluble, organic and insoluble grease,
such as glycerin, is suitable. Water will clean
glycerin.
There are other type of greases which can be used
specifically when certain reagents are used in
the Burettes or Separating Funnels.
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7. |
The use of water, oil or
glycerol is recommended on both tubing and rubber
bung when inserting glass tubing into a bung.
Always wear heavy protective gloves or similar
protection when carrying out this operation. |
8. |
Always fire polish rough
ends of glass tubing before attempting to insert
into flexible tubing. The lubricants recommended
above may also prove useful. |
9. |
Never attempt to pull a thermometer
out of a rubber bung. Always cut the bung away.
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| PERSONAL
SAFETY |
1. |
Use tongs to
asbestos gloves to remove all glassware from heat.
Hot glass can cause severs burns. |
2. |
Protective gloves, safety
shoes, aprons, and goggles should be worn as safety
chemical accidents, spilling or splattering.
|
3. |
Always flush the outside
of acid bottle with water before opening. Do not
put the stopper on the counter top where someone
else may come in contact with acid residue. |
4. |
Special care is needed when
dealing with mercury. Even a small amount of mercury
in the bottom of a drawer can poison the room
atmosphere. Mercury toxicity is cumulative and
the element's ability to amalgamate with a number
of metals is well known. After an accident involving
mercury, the area should be cleaned carefully
until there are no globules remaining. All mercury
containers should be kept well-stoppered.
|
5. |
Never drink from a beaker. A beaker left specifically
for drinking is a menace to the laboratory. Do not
taste chemicals for identification. Smell chemicals
only when necessary and by waiting a small amount
of vapour towards the nose. |
6. |
Avoid pipeting by mouth, particularly when using
concentrated acids, alkalis or potentially biohazardous
materials. Use mechanical means such as a rubber
bulb or an automatic dispenser. |
7. |
Never fill receptacle with material other than
that called for by the label. Label all containers
before filling. Throw away contents of unlabelled
containers. |
8. |
To avoid breakage when clamping glassware, do
not permit glass-to-metal contact and do not use
excessive force to tighten the clamps. |
9. |
Do not look down into a test tube being heated
or containing chemicals and do not point its open
end at another person. A reaction might cause the
contents to be ejected, resulting in injury. |
10. |
Spattering from acids, caustic materials and strong
oxidizing solutions on the skin or clothing should
be washed off immediately with large quantities
of water. |
11. |
When working with chlorine, hydrogen sulphide,
carbon monoxide, hydrogen cyanide and other very
toxic substances, always use a protective mask or
perform these experiments under a fume hood on a
well ventilated area. |
12. |
In working with volatile materials, remember that
heat causes expansion and confinement of expansion
results in explosion. Remember also that danger
exists even though external heat is not applied. |
13. |
Perchloric acid is especially dangerous because
it explodes on contact with organic materials. Do
not use perchloric acid around wooden benches or
tables. Keep perchloric acid, wear protective clothing. |
14. |
When using hot plates and other electrical equipments,
ensure the wire and plugs are in good condition.
Never handle Electrical connection with damp hands.
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| CLEANING |
| Successful experimental results can only be achieved
by using a clean apparatus. In all instances laboratory
glassware must be physically clean, in nearly all cases
it must be chemically clean and in specific cases it must
be bacteriologically clean or sterile. There must be no
trace of grease and the safest criteria of cleanliness
is the uniform wetting of the glass surface by distilled
water-this being of the utmost importance for glassware
used for volumetric methods. Any prevention of uniform
wetting of the surface will introduce errors such as distortion
of the meniscus and accuracy of volume. |
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