# Physical Properties & Density

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Physical Properties & Density

Physical Properties How would you describe someone or something?
weight, height, length, eye color, hair color It is easy to identify chemicals, compounds and elements based on their physical properties also. EX: color, odor, states of matter to name a few.

Mass A physical property that every object possesses is mass.
The amount of mass in a person will never change when the object is moved from place to place. Doesn’t change with gravity

Weight A physical property that is related to mass is weight. The weight of a dog will change if it is moved to Uranus because weight is determined by gravity.

Gravity The greater the mass of an object, the more strongly it attracts other objects. The weight of a dog would be heavier on earth than on the moon, because the earth’s mass is larger than the moon’s

Physical changes do not change the identity of Substances
Some physical changes would be boiling of a liquid melting of a solid dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION. Physical changes do not change the identity of Substances

Chemical Change Click for movie 2 H2(g) + O2 (g) --> 2 H2O(g)

Chemical Change Burning hydrogen (H2) in oxygen (O2) gives H2O.
Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.

Density Another physical property that can be used is density.
Density is a measure of the relationship between mass and the volume it occupies. Think of it like using weight and height for babies 95th percentile for height, 30th for weight

DENSITY - an important and useful physical property
Aluminum Platinum Mercury 13.6 g/cm3 21.5 g/cm3 2.7 g/cm3

Buoyancy and Density One factor that density controls is floating and sinking. Objects float and sink because of their density. The density of water is 1.0 g/mL. The density of cork is 0.34 g/mL. The density of lead is 13.9 g/mL.

Name some other items that will
Buoyancy and Density Compounds that are less dense than water float. Name some other items that will float in water. Compounds that are more dense than water sink. Name some other items that will sink in water.

Density Units Density = Mass/Volume Density is recorded as g/mL.
Density = unit mass per unit volume. Density = Mass/Volume Density is recorded as g/mL. Mass is measured in g. Volume is measured in mL.

Density of Some Common Substances
Substance Density (g/cm3)   Air Feathers Wood(Oak) Ice    Water  1.00 Bricks  Aluminum  2.70 Steel  Silver  Gold

Density Review

Floating Liquids Which diagram represents the liquid layers in the cylinder? (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) ) ) K V W K V W W V K

Solution (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) V W K

PROBLEM: Mercury (Hg) has a density of 13. 6 g/cm3
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg? Convert volume to mass Note: 1 ml is the same as 1 cm3

Bloody Density If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given? 1) L 2) L 3) L Caution: The units are liters!

Solution Unit Plan: g mL L 575 g x 1 mL x 1 L = 0.548 L 1.05 g 1000 mL
1) Unit Plan: g mL L 575 g x mL x 1 L = L 1.05 g mL

Light or Heavy Metals You have 3 metal samples. Which one will displace the greatest volume of water? Discuss your choice with another student. 25 g Al 2.70 g/mL 45 g of gold 19.3 g/mL 75 g of Lead 11.3 g/mL

Solution 1) 25 g Al x mL = mL g 25 g Al 2.70 g/mL

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