Science AHSGE

1
Science AHSGE

• Standard I-1, part 2- Appropriate Laboratory
  Materials

2
Measurement

• Universal system of measurement
• Systeme International (SI) or Metric System
• Based on units of ten
• King Hendry Died By Drinking Chocolate Milk
• Kilo- 1000s (k)
• Hecto- 100s (h)
• Deka- 10s (Da, Dk)
• Base
• Deci- 10ths (d)
• Centi- 100ths (c)
• Milli- 1000ths (m)
• Base units
• Volume, space- liters,cm3
• Mass/weight- Grams
• Distance, height, width, length- Meters

3
Measurement

• Accuracy refers to the agreement between a
  measurement and the true or correct value.
• Precision refers to the repeatability of
  measurement.
• Error refers to the disagreement between a
  measurement and the true or accepted value.

4
Glassware

• Do not use glassware that is broken, chipped or
  cracked.
• Always use tongs or a heat-resistant glove to
  heat glassware.
• a. Point test tube away from yourself and
  others when heating.
• b. Allow to cool before storing.
• 3.    If a glassware breaks, do not touch with
  bare hands. Place in special broken glass
  container.

5
Glassware

• Graduated cylinder-piece of laboratory glassware
  used to accurately measure out volumes of
  chemicals for use in reactions.
• Generally more accurate and precise for this
  purpose than flasks.
• Read from bottom of meniscus
• Fluid displacement- Determine the volume of an
  irregular solid by placing in a graduated
  cylinder with a known amount of fluid and
  measuring the difference

6
Glassware

• Beaker- Simple container for liquids, very
  commonly used in laboratories.
• Generally cylindrical in shape, with a flat
  bottom
• Do not use to measure volume of a liquid.
• Use for holding and pouring liquids.

7
Glassware

• Burette (also buret)- Vertical cylindrical piece
  of laboratory glassware with a volumetric
  graduation on its full length and a precision
  tap, or stopcock, on the bottom.
• Used to dispense known amounts of a liquid
  reagent in experiments for which such precision
  is necessary, such as a titration of an acid
  experiment.
• Burettes are extremely precise class A burettes
  are accurate to 0.05 mL.

8
Glassware

• Flask- Wider vessel "body" and one (or sometimes
  more) narrower tubular sections at the top called
  necks which have an opening at the top.
• Flasks can be used for making solutions or for
  holding, containing, collecting, or sometimes
  volumetrically measuring chemicals, samples,
  solutions, etc. for chemical reactions
• Other processes such as mixing, heating, cooling,
  dissolving, precipitation, boiling (as in
  distillation), or analysis.

9
Glassware

• Pipette (also called a pipet, pipettor or
  chemical dropper)- Instrument used to transport a
  measured volume of liquid.
• Works by creating a vacuum above the
  liquid-holding chamber and selectively releasing
  this vacuum to draw up and dispense liquid.
• May have a bulb for suction.

10
Glassware

• Petri dish- Shallow glass or plastic cylindrical
  dish that biologists use to culture cells, which
  can be bacteria, animal, plant, or fungus
• Agar is a gelatinous substance chiefly used as a
  culture medium for microbiological work

11
Glassware

• Test tube (culture tube)- Piece of laboratory
  glassware composed of a finger-like length of
  glass tubing, open at the top, with a rounded
  U-shaped bottom.
• Typically used by chemists to retain multiple
  discrete samples of materials, usually liquids,
  during chemical procedures and experiments
• Designed to allow easy heating of these samples.

12
Glassware

• Microscope slide- thin sheet of glass used to
  hold objects for examination under a microscope.
• Wet mount- Object to be viewed is prepared, or
  mounted, in water underneath a cover slip

13
Mass Measurement

• Balance (also balance scale, beam balance or
  laboratory balance) is used to measure the mass
  of an object.
• Triple-beam balance Balance with a pan and
  three beams with sliding masses called riders
• At one end is a pointer
• Indicates whether the mass on the pan is equal to
  the mass on the beams

14
Mass Measurement

• Spring scales typically measure force due to
  gravity, which can be measured in units of force
  such as newtons or pounds-force.

15
Mass Measurement

• Analytical balance-instrument used to measure
  mass to a very high degree of precision. The
  weighing pan(s) of a high accuracy (0.1 mg or
  better)
• Inside a see-through enclosure with doors so dust
  does not collect and so any air currents in the
  room do not affect the delicate balance.

16
Time Measurement

• Stop Watch- does what its name implies
• enables hand timing
• has millisecond accuracy and no artificial limit
  on hours

17
Distance Measurement

• Distance is the measurement from one point to
  another.
• How far away something is
• Can be length, width, height, depth, altitude,
  etc.
• Sometimes need to measure before the volume of a
  regular solid can be determined
• V L x W x H

18
Distance Measurement

• Ruler- the instrument used to rule lines and the
  calibrated instrument used for determining
  measurement

19
Distance Measurement

• A tape measure or measuring tape is a ribbon of
  cloth, plastic, or metal with linear-measure
  markings, often in both imperial and metric
  units.
• A meter stick measures up to 40 inches (3.281
  feet)
• A yard stick measures up to 36 inches (3 feet)

20
Optical Instruments

• A microscope -instrument for viewing objects that
  are too small to be seen by the naked or unaided
  eye.
• optical instrument containing one or more lenses
  that produce an enlarged image of an object
  placed in the focal plane of the lens(es).

21
Optical Instrument

• Simple Microscope- Microscope with only one lens
• Compound Light microscope- Microscope with more
  than one lens which uses light to transmit image
  to your eye

22
Optical Instrument

• Electron microscope- uses electrons to illuminate
  and create an image of a specimen
• Transmission electron microscopy (TEM) involves a
  high voltage electron beam emitted by a cathode,
  usually a tungsten filament, and focused by
  electrostatic and electromagnetic lenses
• Scanning Electron Microscope (SEM) produces
  images by detecting low energy secondary
  electrons which are emitted from the surface of
  the specimen due to excitation by the primary
  electron beam

23
Optical Instrument

• Reflection Electron Microscope (REM) involves
  electron beams incident on a surface, but instead
  of using the transmission (TEM) or secondary
  electrons (SEM), the reflected beam is detected

24
Optical Instrument

• Telescope- an instrument designed for the
  observation of remote objects and the collection
  of electromagnetic radiation

25
Optical Instrument

• Magnifying glass- (Hand lens) a convex lens which
  is used to produce a magnified image of an object