plzz someone give me the format of practical writing on basic laboratory techniques. i will mark them as brain list
Answers
Answer:
Working of Bunsen burner.
Cutting a glass tube or glass rod.
Bending a glas tube.
Drawing a glass jet.
Use of wash bottle.
Boring a cork.
mark me as brainliest...........
Answer:
it's complete work:)
Explanation:
T HE laboratory apparatus for carrying out reactions, in general, is made up
of glass. It is because glass is resistant to the action of most of the
chemicals. Generally, two types of glass are used for making apparatus
for laboratory work. These are soda-lime glass and borosilicate glass.
Soda-lime glass, which is made by heating soda, limestone and silica, softens
readily at about 300-400°C in the burner flame. Therefore, on heating glass
tubings made of soda-lime glass easily softens and can be bent. Coefficient of
expansion of soda glass is very high, therefore on sudden heating and cooling, it
may break. To avoid breaking, it should be heated and cooled gradually. Annealing
by mild reheating and uniform cooling prevents breakage. Such glass should
not be kept on cold surface while it is hot, since sudden cooling may break it.
Borosilicate glass does not soften below 700-800°C and requires oxygen-
natural gas flame for working. Natural gas mixed with oxygen is burnt to get the
oxygen-natural gas flame. Coefficient of expansion of this glass is low and
apparatus made of this glass can withstand sudden changes in temperature.
Therefore, apparatus used for heating purposes is made from borosilicate glass.
On heating, glass apparatus made up of borosilicate glass does not distort.
In the following pages you will learn about some of the techniques of handling
glass tubes and glass rods without injuring yourself. Also, you will learn the
techniques of using laboratory apparatus and equipments.
2.1 CUTTING OF GLASS TUBE AND GLASS ROD
Material Required
• Soda-glass tube : 15 cm long
• Soda-glass rod : 15 cm long
• Triangular file : One
Procedure
(i) Place the glass tube or the glass rod on the table and press it with your left handKeep the lower end of a triangular file with its sharp edge
perpendicular to the tube to be marked and pull it towards
you to make a single deep scratch on the glass tube or the
glass rod at a desired length
(iii) Keep thumbs of your hands on both sides, very close and
opposite to the scratch as shown in and break the
glass tube or rod by applying pressure from your thumbs
in a direction away from you . Break the tube/
rod by holding it with a cloth so that hands are not harmed.
(iv) If the glass tube does not break, make a deeper scratch at
the point marked earlier and make a fresh attempt.
(v) Trim any jagged edge by striking with a wire gauge .
(vi) Heat the freshly cut edge of the tube gently in the flame to
make the edges round and smooth . This is called
fire polishing. For fire polishing, first continuously warm the
cut end in the Bunsen flame and then rotate it back and
forth until the edge is rounded. Too much heating may distort
the rounded edge Precautions
(a) Make a single deep scratch at the desired length with one stroke of the file.
(b) To avoid injury, carry out the filing and breaking of the glass tube/rod away
from the face as far as possible and hold the glass tube / rod with the help of a
piece of cloth to avoid injury to hands.