Laboratory organization, management and safety methods - Chapter # 03 : LABORATORY TECHNIQUES - Course code # 8629 - AIOU

1. LABORATORY
TECHNIQUES
Course code # 8629
Chapter # 03
Course Name: Laboratory organization,
management and safety methods

2. CONTENTS
• 1 Glass Working Skills
• 2 Practices in Wood Working
• 3 Working with Electricity
• 4 Working with Chemical Regent

3. Laboratory glassware
• Laboratory glassware refers to a variety of equipment used in
scientific work, and traditionally made of glass. Glass can be blown,
bent, cut, molded, and formed into many sizes and shapes, and is
therefore common in chemistry, biology, and analytical laboratories.
Many laboratories have training programs to demonstrate how
glassware is used and to alert first–time users to the safety hazards
involved with using glassware.

6. Anneal
The process of removing stresses introduced into the glassware during the
glassblowing process.
Annealing Oven
A piece of equipment used to remove the stress in glassware.
Annealing Point
The temperature at which the stress in glass is removed. Annealing point
temperatures are different for each type

7. Conti…………
Burners
These devices are usually designed for stationary use at the bench or
lathe. The glass being worked is moved into and around the flame. The
flame size is determined by valves that adjust the flow and mix of fuel
gas and oxygen.
.

8. Conti………………..
• Calipers
• A tool used to measure the internal diameter or the outside diameter
of glass tubing or rod, and wall thickness.
• Corks
• These are fixed size stoppers for temporarily sealing openings in the
glass. They are typically made of natural cork or rubber

9. Conti……………
Cutting Tool
An instrument used to scratch the surface of glass
tubing or rod. Example: Tungsten Carbide Knife.
Diamond Scribe
A hand-held tool with a diamond point used to make a
permanent mark on glass.

10. Conti….
File
Files may be used to scratch the glass tube or rod surface. Three-corner
(triangular) files are the easiest to use.
Fire Polishing
The process of using a flame to smooth the ends of glass tubing or rod.
Flint Lighter
A handheld tool used to create a spark when igniting a torch or burner.

11. Conti……….
Glassblowing Lathe
A piece of equipment used as an aid in glass rotation.
Glass Saw (Cut-Off Wheel)
An electric-powered tool used to cut glass tubing and apparatus.
Graphite/Carbon Rods and Shapers
Tools used to form or shape hot glass. These hand held tools may be
found in rod, flat , taper and custom forms.

12. Conditions for Glass Working
Some conditions support glass working. Some are discussed as under.
a) Temperature
A room temperature of about 25 C0 is usually found suitable. Higher
temperature is acceptable, whereas lower temperature is often not
suitable for glass working

13. Conti………….
b) Bench
The bench must be covered with a sheet of asbestos
c) Lighting
The flame use for manipulation of glass is often non- luminous
d) Waste Box.
While working with glass, a sufficient amount of glass is broken

14. Skills of Glass Works
Following glass working skills are discussed below only for
introduction.
a) Cutting and Bending the Glass tube.

15. Bending the glass tube
Take a 9-10 cm long glass tube. Place this tube on the upper portion of the
flame holding in both hands as shown in the figure. Go on rotating the tube
slowly and continuously so that heat is uniformly distributed. Heat till glass is
soft enough. Try to press it gently toward the bending position. Keep on
bending till the required angle is obtained. Remove from the flame and cool it
on the sheet

16. Drawing out a Jet
• Take a glass tube and heat it lengthwise at its middle point. Rotate the tube
slowly in the flame so that heat is uniformly distributed. Continue heating till
the glass becomes soft enough. Now pull both the ends ourwardly to pull them
apart. Allow it to cool and give jerk to cut the tube.

17. Boring the Cork
Cork is used for preparation of gases and distillation process. Take a cork of size
equal to the mouth of the bottle. Soften it by pressing it smoothly. Now take a
borer of small diameter than the diameter of the tube to be fitted in it. Place the
cork on the table with its narrow end upward.
Hold the borer in right hand and cork in left hand; apply force on the border
with a twisting motion. When half of the borer has been bored, take the borer
out and reverse the cork. Remove the borer after the cork has been bored from
none face to the other. Now fit the glass tube and use it

18. 2 Working with Wood
• Woodworking tools are classified according to use:
a) Measuring and Laying out
For good finished is subjected to application of correct techniques. For
measuring rule is used and for laying protractor is used. A pencil and rule is
used where extreme accuracy is not needed. Steel rule and knife can be used
to get more accurate measurements. When a duplicate of a piece is needed, it
is done by placing the already cut piece.

19. b) Cutting
After measurement and layout, cutting stage occurs. The right kind of saw is
needed for this purpose. Accurate sawing depends on a good sharped saw,
and applying right technique in cutting.

20. c) Planning
• Wooden boards are planed with planer. There are many types of adjustable
planers, but most of them are already assembled and adjusted. Its basic
techniques lie in squaring a board.

21. d) Chiseling
• After a board, has been cut, planed are needed to join with other parts or
boards. For this it should be chiseled. Chiseling is not to bore a board. This
operation is done to join parts.

22. e) Boring and Drilling Holes
• Now a day many drilling devices having different drill sizes are available in the
market. Holes are bored or drilled in the wood for screws and bolts. Point out
marks where to drill holes. Then make a small bore with borer machine. Bores
will avoid the wood rupture and nails are drawn easily into the wood.

23. f) Using Nails and Screws for Joining the wooden pieces
• After wooden pieces/ boards have been bored nails and screws are used to
join or fasten different boards or pieces of wood. Small hammer is used to
draw the nails or screws into the wooded parts to be fastened. Sometimes
there is a fear of corroding the nails or screws, so use oil or grease before
insertion of nails/ screws into the wood

24. 3 Working with Electricity
• Wiring a 3-Pin Plug
In three pin plug there are three pins, earth pin situated on top. The
green/yellow striped wire is connected to it.
• Renewing a Fuse
Before replacing a fuse in any electrical instrument, the electric current
should be turned off, and the appliance should be disconnected from
the supply.

25. Electrical Meters
• There is a considerable number of meters used for specific purposes. A
voltmeter is used to measure electromotive force or the potential
difference between two points.
• Ammeters are used to measure the amount of current that is flowing in a
circuit.
• Ohmmeter is used to measure the resistance of electrical components in
Ohms.
• AVO meter is a three -in -one meter. This is an ammeter, voltmeter and
ohmmeter.
• It is necessary for students and teachers that they must use relevant meter
for specific function.

26. Working with Chemical Reagents
• Solutions
• Solutions often must be prepared in fairly large quantities so that they can last
for a few weeks or months depending on the kind of solutions. Indicator
solutions may last for a year or more. Containers holding these solutions should
be labeled and their labels should be checked from time to time.
• Quite a number of solutions are best stored in big plastic containers that can
hold from 1 to 3 liters. These are called bench or stock solutions

27. Handling Chemicals
• Chemical substances must be handled carefully so that they will not
spill on hands, clothes or bench tops causing stains or burns

28. 3 Techniques for Pouring and Transferring
Liquids
• 1. Check the label of the bottle to see whether it contains the correct solution.
• 2. Remove the stopper and hold it between little finger and edge of hand.
• 3. Grasp the bottle on the labeled side to ensure that no liquid is spilled over
the label.
• 4. Pour the solution. Make sure to get the last drop by allowing the lip of the
bottle to touch the container.
• 5. Replace the stopper.
• 6. Return reagent bottle to its original place. Read the label again to make sure
the correct chemical was taken

31. Preparation of Stock Solution from Commercial
Concentration (Dilution
• Commercial acids and bases such as sulphuric acid, hydrochloric acid,
ammonium hydroxide and many other liquids are generally purchased
in large bottles. Labels on the bottles give the ranges for specific
gravity and percent of solute. This specification may not exactly
represent the actual specific gravity or percent but they are close
enough to be used without much error.

32. 7 Making Standard Solutions by Weighing
• A good and precise weighing balance is necessary for making
standard solutions by weighing. The solid is weighed in weighing or
on a small watch glass. If the solid is small, the solid is washed directly
into a measuring flask through a clean funnel by using a jet of distilled
water from a wash bottle.

33. Conti…………..
• When the weight of solid sample is large or the solid requires heating
to dissolve rapidly, it is transferred with water into a container. If the
solid is heated make sure it is cool before pouring it into a graduated.
Again wash the beaker with distilled and add all the washings to the
liquid in the graduated flask.
• Make sure that the solute has dissolved in the solvent before topping
the solute with water up to the graduation mark.

34. Solutions for Stain Removal
• There are special solutions for removing a particular kind of stain.
• 1. Carbon deposits. Use 4 g of trisodium phosphate and 3 g of
sodium oleate in 100 ml of water.
• 2. Iodine. Use sodium thiosulphate solution.
• 3. Indelible pencil. Use acetone.
• 4. Iron stains. Use dilute or concentrated hydrochloric acid.
• 5. Sulphur, Use ammonium sulphide solution.

35. Indicators
• One problem met in teaching of acid and base reactions is the lack of
chemical indicators. This problem can be overcome by using indicators made
from the colored petals and leaves of plants. Many plant pigments can be
used to indicate the pH of solutions