Why do we have them? When we measure things, we want to measure to the place we are sure of and guess one more space.
So, they show the uncertainty in our measurements
Since the marks on this ruler are subdivided as they are, our answer for the length of this nail has 3 significant figures.
However, we only have significant figures when we are measuring something. Counting will give you an exact number.
Lab Equipment
Beaker Holds chemicals during mixing, heating, and storage Acts like a bowl Inaccurate measuring device
Erlenmeyer Flask Holds chemicals during mixing, heating, and storage Acts like a bowl Inaccurate measuring device
Volumetric Flask Holds chemicals during mixing and storage Accurate measurement of a specific volume
Funnel Aids in pouring and filtering process
Watch Glass Acts as a cover during heating and storage Looks like a giant contact len
Evaporating Dish Container used to allow materials to evaporate
Crucible and Cover Used to hold materials that need to be heated to higher temperatures
Crucible Tongs Used to hold heated crucibles
Bunsen Burner Used to heat materials
Striker Used to light burners
Balance Used to determine the mass of materials
Graduated Cylinder Used to measure liquids accurately Must look at meniscus of the liquid when taking readings
Iron Ring Attaches to ring stand Holds various equipment while they are heated
Buret Clamp Attaches to ring stand Holds burets during titrations
Utility Clamp Attaches to ring stand Holds various thin equipment while they are heated
Goggles Protect eyes during experiments
Ring Stand Used to support devices during laboratory procedures
Buret Used to accurately and slowly add liquids Used most often in titration experiments
Thermometer Used to measure the temperature of various materials
Gas-collecting tube Tube used to collect gases. Usually used in the inverted position
Test Tube Used to hold small samples during heating and storage
Test Tube Rack Used to hold multiple test tubes
Test Tube Holder Used to hold one test tube, usually during heating or transporting test tube
Forceps Used to pick up and separate small solids
Spatula Used to scoop small quantities of solids Can be used to scrape the inside of various equipment
Mortar and Pestle Used to crush and grind materials
Pipet Used to dispense small quantities of liquids
Stoppers Come in various sizes Used to block openings of various equipment
So, let us practice with reading different pieces of equipment
Answer to Worksheets Scales 622.89 g 153.70 g 200.54 g 128.192 g
Answer to Worksheets Thermometers Liquid Volume 68.0 56.0 mL -2.8 11.0 -1.1 28.1 16.0 8.0 -11.5 98.7 Liquid Volume 56.0 mL 4.35 mL 23.7 mL 16.8 mL 76.0 mL 5.3 mL 32.0 mL 3.5 mL 47.0 mL
Instruments around the room Beaker Buret Volumetric Flask Graduated cylinder Scale Erlenmeyer Flask Thermometer
Homework Look through your textbook. Find 10 pictures that show a piece of chemical equipment being used. Name the page, the piece of equipment and describe how it is being used.