Lab Techniques

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

Practice Precision 1. Measure the width of your notebook paper in centimeters 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 Techniques  Measuring mass directly  Measuring out a substance  Finding mass by difference

Measuring Volume  Regular Solid  V = L x W x H  Irregular solid  Water displacement method  Liquids  Graduated cylinder  Buret

Water Displacement Method

Reading the Meniscus

Units for Volume  cm 3 or milliliter  Regular Solid: cm x cm x cm = cm 3  1 cm 3 is equivalent to 1 mL

Lab Techniques  Decanting  Filtering  Lighting a Bunsen Burner

Decanting  Separating 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

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.

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.