Lab Techniques. Instrument Precision Record all available digits from a measurement instrument plus one estimated digit 5.75 cm.

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.