Laboratory Hardware Part III

1
Laboratory Hardware Part III

• Bioscience, Equipment Unit
• Hot/ Stir Plate and Balances

2
Bellwork

• When you go to the doctor for a physical, what
  type of scale is used to get your weight? Do you
  know how they use the scale and if so please
  describe?

3
Objectives

• Use hot plates/stirrers
• Understand how to identify, select, and use
  laboratory balances

4
Terminology

• Hot plate
• Stir Plate
• Zero/ Tare

5
Heating 

• What type of stove do you have at home? Is
  your stove type similar to any lab equipment you
  have used? If so describe if not then describe
  your stove burner and how you control it?

6
Lab bench heating in the Lab

• There are two common ways to heat a reaction or
  a piece of glassware in the lab

With a gas Bunsen Burner
With an Electric Hot Plate
7
Think-Pair-Share

• Considering the Bunsen Burner and the Hot Plate
  which would be preferable for use in a
  Biosciences lab? Give at least two reasons for
  your choice.
• If you are stuck try to consider safety and
  convenience when formulating your answer.

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8
The Hot Plate

• The standard for lab top heating.
• Safer than a Bunsen Burner when using flammable
  solvent
• No need for gas line
• Many have built in digital temp gauges
• Controlled with a dial.
• Many are dual Hot and Stir plates.

9
Using The Hot Plate

• Plug in and pre-heat to desired temperature (if
  digitally controlled)
• Place solution to be heated on hot plate with a
  thermometer in it (even if there is a digital
  temperature readout on hot plate).
• Heat for desired period of time.
• It may be necessary to cover solution with
  para-film to help keep volume constant
• Turn plate off but do not unplug until Surface
  Hot light goes out.

10
Stir Plate

• Used to automatically stir a solution by way of
  a magnetic stir bar.

The magnetic stir bar is placed in the beaker
with the solution to be stirred.
11
Using a Stir Plate
Once the glassware to be stirred is on the stir
plate, plug it in. Slowly increase the speed of
the stirrer until desired speed is reach, a
controlled whirlpool.
If splashing occurs lower speed dial
12
Finger Flash

• When finished using a hot plate
• Unplug immediately and so as not to leave on
  accidently
• Unplug only after Surface hot light turns off
• Unplug only if the plate is cool to the touch
• Show the correct number of fingers for the
  appropriate response

13
Balances and Scales

• Manual Balances

Electronic Balance/ Scale
14
Electronic Balance

• Similar to the balance used to get your weight
  in the doctor office.
• Digital balance generally will report weights in
  metric (mg, g, and kg) and in imperial (oz, and
  lbs.)
• Which unit will we be using in the lab and why ?

15
Our Electronic Balance

• Most common balance in a lab
• Gram scales tens place
• 0.0g to 500.0g
• Milligram scales thousands place
• 0.000g to 100.000g

We have _________ balance in our lab
16
Which Electronic Balance Should Be Used

• On a slate indicate which balance should be used
  and in less than 12 words why?
• Lisa needs to weigh out 2.225g of substance A
• John needs to weight out 100.0g of substance B

17
Using a Digital Balance

• We will fill out an SOP then you will practice
  in the lab.
• Safety
• Never push down on the scale weigh platform
• Do not weigh liquid unless told to do so.

18
Digital Balance SOP

• Insure balance is plugged in and set to metric
  units. If you need to change this touch the
  Units button.
• Direct weighing determining the mass of
  something.
• Touch the Zero or Tare button and wait until
  the balance read only zeros. Now carefully place
  the object on the balance and wait for numbers to
  stop changing before recording mass and units

19
Digital Balance SOP Cont. I

• Dispensing a particular mass determining the
  mass of something.

1. Use weight paper/ boat or glassware directly on
   weigh platform.
2. Touch the Zero or Tare button and wait until
   the balance read only zeros.
3. Weigh out desired amount into weight paper/ boat
   or glassware using a scoopula or spatula.

20
Digital Balance SOP Cont. 11

• Clean balance and box with brush to remove any
  spills.
• Trouble shooting
• If scale gives error message or flashes try
  turning power off to balance and then back on.
• If error message is present when weighing heavy
  glassware or large quantities of substance insure
  you are not over the balances limit.

21
Lab Practice Using a Digital Balance

• You will be using your Digital Balance SOP to
  complete the mini lab at your lab station.
• Work as a group to complete parts A, B, and C.

22
Closure

• Letter to a Friend
• On a ½ sheet of scratch paper write a short
  letter 2-3 sentences explaining how to use a
  digital balance