Lab Techniques. Instrument Precision Record all available digits from a measurement instrument plus...
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Transcript of Lab Techniques. Instrument Precision Record all available digits from a measurement instrument plus...
Lab Techniques
Instrument PrecisionRecord all available digits from a
measurement instrument plus one estimated digit
5.75 cm
Practice Precision1. Measure the
width of your notebook paper in centimeters
26.65 cm
estimated digit
2. Measure the distance between two blue lines in millimeters
7.0 mm
estimated digit
Measuring Mass
Zero the Balance
3 Mass TechniquesMeasuring mass directlyMeasuring out a substanceFinding mass by difference
Measuring VolumeRegular Solid
V = L x W x H Irregular solid
Water displacement methodLiquids
Graduated cylinderBuret
Water Displacement Method
Reading the Meniscus
Units for Volumecm3 or milliliter
Regular Solid: cm x cm x cm = cm3
1 cm3 is equivalent to 1 mL
Lab Techniques Decanting Filtering Lighting a Bunsen Burner
DecantingSeparating a liquid
from a solid (large particles) by pouring off the liquid
Filtering Separating a solid
(small particles) from a liquid through filter paper and a funnel
To make the funnel, fold filter paper in half, in half again, then separate one fold from the rest
http://www.youtube.com/watch?v=ZvxaFCR2-bY
Lighting a Bunsen Burner Connect hose to gas outlet. Have a match ready (do not light
yet). Turn on gas. Listen for gas flow. Strike match and hold it above
the burner to light. Blow out match. Adjust the air vent on the burner
to produce a blue cone in the flame with no yellow tip.
When finished: Turn off gas. Disconnect hose.
High Temp.
Cool Inner Region
Air Vents
To Gas Outlet
GasValve
Clean Up Checklist
Wet the match head to cool and throw away.
Throw away wooden sticks. Pour any water down the drain. Dump wet sand into the trash. Wipe down lab counter. Straighten and organize lab equipment. Wash your hands.