Units of MeasurementPacket #3

Chapter #1

IntroductionIn class, two “quantities,” volume and mass,

have been mentioned and are measured using a particular type of unit.

What are some of the other “quantities” and units used in science?

Quantities & UnitsQuantity Symbol Unit Abbreviation

Length l meter m

Mass m kilogram kg

Time t second s

Temperature T kelvin K

Amount of a substance

n mole mol

Electrical current

I ampere A

Volume v millilitre ml

PrefixesPrefix Abbreviati

onExponential Multiplier

Meaning Example using length

Kilo- k 103 1000 1 kilometer (km) = 1000 meters (m)

Hecto- h 102 100 1 hectometer (hm) = 100 m

Deka- da 101 10 1 dekameter (dam) = 10 m

Deci- d 10-1 1/10 (0.1) 1 decimeter (dm) = 0.1 m

Centi- cm 10-2 1/100 (0.01) 1 centimeter = 0.01 m

Milli- mm 10-3 1/1000 (0.001) 1 millimeter = 0.001 m

Conversions

Conversions IWithin quantities, it is important for

scientists to convert a measurement from one unit to another.

Let us do some examples.

Conversions IIIdentify the quantity and unit given and the

unit that you want to convert to.Using the equality that relates the two units,

set up the conversion factor that cancels the given unit and leaves the unit that you want to convert to.

Multiply the given quantity by the conversion factor. Cancel units to verify that the units left are the ones you want for your answer.

Conversions IIIExamples

Density

Density IIs a physical property of matterThe quality or condition of being dense.

A measure of “thickness”Density = Mass/Volume

Densities of Various SubstancesSubstance Density (g/cm3) at 25°C

Hydrogen Gas (H2) 0.0000824

Carbon Dioxide (CO2) 0.0018

Ethanol (ethyl alcohol) (C2H5OH) 0.789

Water (H2O) 0.997

Sucrose (table sugar) (C12H24O12) 1.587

Sodium Chloride (Salt) (NaCl) 2.164

Aluminum (Al) 2.699

Iron (Fe) 7.86

Copper (Cu) 8.94

Silver (Ag) 10.5

Gold (Au) 19.3

Osmium (Os) 22.6

Density Lab

IntroductionEveryone knows that vegetable oil floats on water. That’s

because the two liquids have different densities. Density is basically how much “stuff” is smashed into a particular area… or a comparison between an object’s mass and volume. So, the exact same volume of two liquids may actually have different masses, so they would have different densities. That’s why vegetable oil floats on top of water.

But, vegetable oil and water are just one way to explore density. What if you could float seven different liquids in seven different layers? We’ll show you how to be amazing and make a seven-layer density column!

MaterialsLight Karo SyrupWaterVegetable OilDawn dish soap (blue)Rubbing alcoholLamp OilHoneyGraduated cylinderFood Coloring or True Color Coloring TabletsFood baster9 oz. portion cups

Lab InstructionsMeasure 8 ounces {235 ml} of each type of

liquid into the 9 oz. portion cups. You may want to start the experiment by coloring each of the liquids to make a more dramatic effect in your column. Light Karo syrup is easier to color than the dark syrup. The only liquids that you may not be able to color are the vegetable oil and the honey.

Lab Instructions IIStart your column by

pouring the honey into the cylinder. Now, you will pour each liquid SLOWLY into the container, one at a time. Make sure you pour them in the following order. HoneyKaro syrupDish soapWaterVegetable oilRubbing AlcoholLamp oil

Lab Special NoteIt is VERY important to pour the liquids

slowly and into the center of the cylinder. Make sure that the liquids do not touch the sides of the cylinder while you are pouring. Also, it’s okay if the liquids mix a little as you are pouring, the layers will always even themselves out because of the varying densities.

As you pour, the liquids will layer on top of one another. After you pour in the liquids you will have a Seven-layer science experiment. Density is too cool!

Observations & Why IThe same amount of two different liquids will have different

weights because they have different masses. The liquids that weigh more (have a higher density) will sink below the liquids that weigh less (have a lower density). To test this, you might want to set up a scale and measure each of the liquids that you are pouring into your column. Make sure that you are measuring the weights of equal portions of each liquid. You should find that the weights of the liquids correspond to each different layer of liquid. For example, the honey will weigh more than the Karo syrup, etc. By weighing these liquids, you will find that density and weight are closely related.

Here are the densities of the liquids used in the column as well as other common liquids (measured in g/cm3):

Observations & Why II