Physical Properties & Density. Physical Properties How would you describe someone or something? How would you describe someone or something? weight, height,

Physical Properties & Physical Properties & DensityDensity

Physical PropertiesPhysical Properties

How would you describe someone or How would you describe someone or something?something?

weight, height, length, eye color, hair colorweight, height, length, eye color, hair color

It is easy to identify chemicals, compounds It is easy to identify chemicals, compounds

and elements based on their and elements based on their physical properties also. also.

EX: EX: color, odor, states of matter to name a color, odor, states of matter to name a fewfew..

MassMass

A physical property A physical property that every object that every object possesses is possesses is massmass..

The amount of mass The amount of mass in a person will in a person will never change when never change when the object is moved the object is moved from place to place.from place to place.

Doesn’t change Doesn’t change with gravitywith gravity

WeightWeight A A physical physical

propertyproperty that is that is related to mass is related to mass is weight.weight.

The weight of a dog The weight of a dog will change if it is will change if it is moved to Uranus moved to Uranus because because weightweight is is determined by determined by gravity.gravity.

GravityGravity

The greater the mass The greater the mass of an object, the more of an object, the more strongly it attracts strongly it attracts other objects. other objects.

The weight of a The weight of a dogdog would be heavier on would be heavier on earth than on the earth than on the moon, because the moon, because the earth’s mass is larger earth’s mass is larger than the moon’sthan the moon’s

Physical Physical ChangesChanges

Some Some physical physical changes changes would bewould be

boiling of a liquidboiling of a liquid melting of a solidmelting of a solid dissolving a solid dissolving a solid

in a liquid to give a in a liquid to give a homogeneous homogeneous mixture — a mixture — a SOLUTION.SOLUTION.

Physical changes do not change Physical changes do not change the identity of Substancesthe identity of Substances

Chemical Chemical ChangeChange

2 H2(g) + O2 (g) --> 2 H2O(g)

Click for movie

Chemical ChangeChemical Change

Chemical changeChemical change or or chemical reaction — — transformation of one or transformation of one or more atoms or molecules more atoms or molecules into one or more different into one or more different molecules.molecules.

•Burning hydrogen (HBurning hydrogen (H22) in ) in oxygen (Ooxygen (O22) gives H) gives H22O.O.

DensityDensity Another physical property that can be Another physical property that can be

used is used is density.density. Density is a measure of the relationship Density is a measure of the relationship

between between massmass and the and the volumevolume it it occupies.occupies.

Think of it like using weight and Think of it like using weight and height for babiesheight for babies 95th percentile for height, 30th for 95th percentile for height, 30th for

weightweight

DENSITYDENSITY - an important - an important and useful physical propertyand useful physical property

Density mass (g)volume (cm3)

Density mass (g)volume (cm3)

13.6 g/cm13.6 g/cm33 21.5 g/cm21.5 g/cm33

Aluminum

2.7 g/cm2.7 g/cm33

PlatinumMercury

Buoyancy and DensityBuoyancy and Density One factor that density controls is One factor that density controls is

floating floating and and sinking.sinking. Objects float and sink because of their Objects float and sink because of their

density.density.

The density of water is 1.0 g/mL.The density of water is 1.0 g/mL. The density of cork is 0.34 g/mL.The density of cork is 0.34 g/mL. The density of lead is 13.9 g/mL.The density of lead is 13.9 g/mL.

Buoyancy and DensityBuoyancy and Density

Compounds that are less Compounds that are less dense than water float.dense than water float.

Name some other items Name some other items that will that will floatfloat in water. in water.

Compounds that are more Compounds that are more dense than water sink.dense than water sink.

Name some other items Name some other items that willthat will

sink in water.sink in water.

Density UnitsDensity Units

Density Density = = unit mass per unit unit mass per unit volume.volume.

DensityDensity = Mass/Volume = Mass/Volume Density is recorded as Density is recorded as g/mL.g/mL.

Mass is measured in g.Mass is measured in g. Volume is measured in mL.Volume is measured in mL.

Density of Some Common SubstancesDensity of Some Common Substances SubstanceSubstance Density (g/cm3)Density (g/cm3)   

AirAir 0.00130.0013 FeathersFeathers 0.00250.0025 Wood(Oak)Wood(Oak) 0.6 - 0.90.6 - 0.9 Ice Ice  0.92 0.92  Water Water  1.001.00 Bricks Bricks  1.841.84 Aluminum Aluminum  2.702.70 Steel Steel  7.807.80 Silver Silver  10.5010.50 Gold Gold  19.30 19.30 

Density ReviewDensity Review

Floating LiquidsFloating Liquids

Which diagram represents the liquid Which diagram represents the liquid layers in the cylinder?layers in the cylinder?

(K) Karo syrup (1.4 g/mL), (V) (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)(1.0 g/mL)

1)1) 2) 2) 3) 3)

K

K

W

W

W

V

V

V

K

Solution Solution

(K) Karo syrup (1.4 g/mL), (V) (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)water (1.0 g/mL)

1)1)

K

W

V

Convert volume to massConvert volume to mass

PROBLEM: Mercury (Hg) has a density PROBLEM: Mercury (Hg) has a density of 13.6 g/cmof 13.6 g/cm33. What is the mass of 95 . What is the mass of 95 mL of Hg?mL of Hg?

PROBLEM: Mercury (Hg) has a density PROBLEM: Mercury (Hg) has a density of 13.6 g/cmof 13.6 g/cm33. What is the mass of 95 . What is the mass of 95 mL of Hg?mL of Hg?

95 cm3 • 13.6 g

cm3 = 1.3 x 103 g

Note: 1 ml is the same as 1 cm3

Bloody Density Bloody Density

If blood has a density of 1.05 If blood has a density of 1.05 g/mL, how many liters of blood g/mL, how many liters of blood are donated if 575 g of blood are are donated if 575 g of blood are given?given?

1) 1) 0.548 L0.548 L

2) 2) 1.25 L1.25 L

3) 3) 1.83 L1.83 L

Caution: The units are liters!

Solution Solution

1)1)

Unit Plan: g mL LUnit Plan: g mL L

575 g x 575 g x 1 mL 1 mL x x 1 L 1 L = = 0.548 L0.548 L

1.05 g 1000 mL 1.05 g 1000 mL

Light or Heavy Metals Light or Heavy Metals

You have 3 metal samples. Which one will You have 3 metal samples. Which one will displace the greatest volume of water?displace the greatest volume of water?

11 2 2 3 3

Discuss your choice with another student.Discuss your choice with another student.

25 g Al2.70 g/mL

45 g of gold19.3 g/mL

75 g of Lead11.3 g/mL

Solution Solution

1)1) 25 g Al x 25 g Al x 1 mL 1 mL = = 9.2 mL 9.2 mL 2.70 g 2.70 g

25 g Al2.70 g/mL