PSC
HAZARDS
Not wearing goggles
Books on table
Group: all very close together, could spill/knock each other and things around them
Unattended bunsen burner
Unsupervised chemicals: could be dangerous chemicals, knocked over
Fooling around
Boxes: in the way of a door, somebody could knock them over (they say fragile as well)
Out of reach: burette is tall and out of reach, could easily spill
Elbow: could knock over a beaker near by
Screw driver in plug socket: could be electrocuted
Tube balancing: It could tip over and spill, filled too much
Split liquid: somebody could slip on it, could be a dangerous chemical
Face too near to (pouring) chemicals
APPARATUS
DIAGRAM
MEASURING #
LIQUIDS
Different levels of accuracy are needed
Apparatus that can be used: pipette, burette, beaker, measuring cylinder
Line up your eyes until the level of liquid in the apparatus to avoid error of paralax
Liquid curves upwards at the edges in the apparatus. This is called the meniscus. Always read from the bottom of the meniscus
MENISCUS - The slope of a liquid in a beaker/cylinder
WHAT APPARATUS TO USE
Beaker - large volume, only if rough volume is required
Measuring cylinder - more accurate than beaker, used for large volumes which don't have to be exact
Pipette - smaller volumes, exact quantities needed, only measures one volume
Burette - used for very accurate measurements of any amount
HOW TO USE A PIPETTE
Never blow the last drops of liquid out of the pipette, this will make your volume inaccurate
Touch the pipette gently against the edge of the container to release the last drop
Now transfer the pipette to the container you want the liquid in and release your index finger from the end of the pipette
Do this until the bottom of the meniscus reaches the small line
Release some of the liquid slowly by twisting the pipette between your middle finger and your thumb. whilst your index finger is still on the top
Keep the end of the pipette over the beaker of liquid
Place your index finger over the top the pipette (quickly)
Suck the liquid up beyond the small line above the swollen portion of the pipette
Time - stopwatch hours (h) minutes (min) second (s)
Temperature - thermometer, degrees Celsius (C)
Mass - spring balance: kilograms (kg)
electric balance: grams (g)
Length - ruler, calipers meter (m) centimeter (cm) millimeter (mm)
Volume of a solid - irregular: measuring cylinder
regular (block, triangular prism, cylinder): ruler and formula
Small: cm3
Large: m3 #
Volume of liquids - beaker, measuring cylinder, pipette, burette litres (l) milliters (ml) (1cm3 = 1ml)
VOLUME OF SOLIDS
REGULAR OBJECTS
Volume of a block = area of base (cm3) x height (cm)
= l x b x h
Volume of a cylinder = area of base x height
PIE x r² x h
Volume of a triangular prism = area of base x height
(b x ph ÷ 2) x h
REMEMBER: radius is half the diameter
When shape has two shapes do not combine into one long sum
IRREGULAR OBJECTS
METHOD OF DISPLACEMENT
Gently place the solid object into the measuring cylinder
Record the new volume of water in the measuring cylinder
Place an amount of water into a measuring cylinder (record the volume)
Subtract the first volume from the second to get the volume of the object
HEATING SUBSTANCES
HOW TO LIGHT A BUNSEN BURNER
Turn the gas half on
Apply the lighted match sideways to the top of the burner
Light your match
Your burner should be showing a yellow flame
Close the air hole
Adjust the air hole to change the type of flame needed
DIFFERENT TYPES OF FLAMES
ALWAYS REMEMBER
BUNSEN BURNER DIAGRAM
Medium flame (air hole half open, gas tap half one)
Roaring flame (air hole fully open, gas tap fully on)
Yellow flame (air hole fully closed, gas tap half on)
Heat the test tube at an angle (flame then covers a bigger area, if eplodes it'll explode to the side
Move the test tube in and out of the flame
Wear goggles
Never point test tube at someone or yourself
LIght match before gas tap is one to avoid a fire ball/safety
When not using your burner leave it on a yellow flame as it is not as hot and vigorous, therefore less dangerous