DensityDensity Density describes how heavy an object is compared to Density describes how heavy an object is compared to

its size. its size.

Think of two cubes that are the same size. One is made Think of two cubes that are the same size. One is made of metal and the other is made of Styrofoam. Which will of metal and the other is made of Styrofoam. Which will be heavier?be heavier?

All substances have different densities, therefore, you All substances have different densities, therefore, you can identify a substance if you know its densitycan identify a substance if you know its density

MassMass

Mass is the amount of substance in an Mass is the amount of substance in an objectobject It is constant no matter where you go, even It is constant no matter where you go, even

the moon.the moon.

To find mass, we put the object on a To find mass, we put the object on a balancebalance Mass is always in gramsMass is always in grams

Volume - two optionsVolume - two options

Volume is how much space an object Volume is how much space an object takes up.takes up.

To find the volume of LiquidsTo find the volume of Liquids Use a graduated cylinder to find the volumeUse a graduated cylinder to find the volume It will be measured in mLIt will be measured in mL

To find the volume of rectangular SolidsTo find the volume of rectangular Solids Measure length, width, and height; then Measure length, width, and height; then

multiply.multiply. It will be measured in cmIt will be measured in cm33

Measuring Solid Volume

10 cm

9 cm

8 cm

We can measure the volume of regular object using the formula length x width x height.

_____ X _____ X _____ = _____

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We can measure the volume of an irregular object using water displacement.

Amount of H2O with object = ______

About of H2O without object = ______

Difference = Volume = ______

Calculate the volume:

Density UnitsDensity Units

When we calculate density, the units we When we calculate density, the units we use are either use are either g/mLg/mL or or g/cmg/cm33. How do we . How do we know which set of units to use?know which set of units to use?

g/ml - g/ml - liquidsliquids volume of liquids are measured in millilitersvolume of liquids are measured in milliliters

g/cmg/cm3 3 for for solidssolids Volume of solids are measured in cmVolume of solids are measured in cm33

WaterWater

What is the density of water?What is the density of water?

If an object is less dense than water it will If an object is less dense than water it will float.float.

If an object has a greater density than If an object has a greater density than water it will sink.water it will sink.

To Calculate DensityTo Calculate Density

The formula to calculate somethingThe formula to calculate something’’s density is:s density is: D = densityD = density M = massM = mass V = volumeV = volume

M

D V

Practice 1Practice 1

V = 15 mLV = 15 mL M = 45 gM = 45 g D = ?D = ?

D = m/vD = m/v 45 g/ 15mL45 g/ 15mL D = 3g/mLD = 3g/mL

Practice 2Practice 2

V = 10 mLV = 10 mL M = 100 gM = 100 g D = ?D = ?

D = m/vD = m/v 100 g/10mL100 g/10mL

D = 10 g/mLD = 10 g/mL

Practice 3Practice 3

M = 45 gM = 45 g D = 9 g/cmD = 9 g/cm33

V = ?V = ?

V = m/dV = m/d 45 g/ 9 g/ cm45 g/ 9 g/ cm33 V = 5 cmV = 5 cm33

Practice 4Practice 4

M = 144 gM = 144 g D = 12 g/cmD = 12 g/cm33

V = ?V = ?

V= m/dV= m/d 144 g/12 cm144 g/12 cm33

V = 12 cmV = 12 cm33

Practice 5Practice 5

D = 12 g/mLD = 12 g/mL V = 3 mLV = 3 mL M = ?M = ?

M = d x vM = d x v 12 g/mL x 3 mL12 g/mL x 3 mL

M = 36 gM = 36 g

Practice 6Practice 6

D = 3.54 g/mLD = 3.54 g/mL V = 22 mLV = 22 mL M = ?M = ?

M = d x vM = d x v 3.54 g/mL x 22 mL 3.54 g/mL x 22 mL

M = 77.88 gM = 77.88 g