Unit 0: Accuracy and precision, Unit Conversions and Chemistry Lab Equipment

How close the measured value is to the true value

Accuracy definition

How close the measured points are to each other

Precision definition

Points of measurement that are close together and close to the true value

both precise and accurate

Points of measurement not close to each other and not close to the true value.

neither precise nor accurate

I fire five arrows and all five of them land in the direct center of where was aimed.

Both precise and accurate example

I fire five arrows at a target. They all land close to the desired area but not close together

accurate, but not precise example

I fire five arrows at a target. they don't land close together or close to the desired area

neither precise nor accurate example

1000 meters =

1 kilometer

1000000 micrometer =

1 meters

3000 g =

3 kg

0.001kg =

1 g

1 millimeter =

0.001 meter

1000 centimeters =

10 meter

1/100 meter =

1 centimeter

20 meters =

2 dekameters

1 cm^3

1 mL

5 meters =

5, 000 millimeters

1 decimeter =

1/100 dekameter

2 kiloliters

2, 000 liters

10 centigrams

1 decigram

This unit is 100 times smaller than a meter

centimeter

This unit is 1,000 times larger than a centimeter

dekameter

Beaker

Erlenmeyer flask

Graduated cylinder

Test tube clamp

Test tube

Test tube brush

Test tube rack

Rubber stopper

Spot Plate

Watch glass

Glass stir rod

Wire gauze

Funnel

Forceps / tweezers

Litmus Paper

Pipet

Wash bottle

Weighing dish

Spatula / Microspatula

Beaker tongs

Bunsen burner

Medicine Dropper

Crucible

Clay triangle

Crucible tongs

Glass Plate

Triangular File

Ring stand

Iron Ring

Utility clamp

Evaporating dish

Mortar and pestle

Electronic balance

Thermometer

Safety goggles

Hot plate

Striker

Meniscus

the curve at a liquid's surface by which one measures the volume of the liquid

water displacement

A technique for determining the volume of a solid placed into a liquid. You look at how much the liquid rises.

cm^2 to m^2

divided by 100^2 or (10,000)

systematic error

Error that shifts all measurements in a standardized way. Decreases accuracy.

random error

Error that is due to chance and is not standardized. Decreases precision.

significant figures (sig figs)

communicate how precise measurements are

how many sig figs in 100

1 sig fig

how many sig figs in 0.050

2 sig figs

how many sig figs in 0.500

3 sig figs

how many sig figs in 3.040 x 10^4

4 sig figs

2.0 x 3.00 to the correct sig figs

6.0

2 x 3.0 to the correct sig figs

6

2.00 x 3.000 to the correct sig figs

6.00

4.0 + 1 to the correct sig figs

5

4.00 + 1.0 to the correct sig figs

5.0