Density - the amount of mass a material has for a given volume

We can calculate density using the formula: . Density= Mass/Volume or D = m/v A concrete cube will weigh more than a cube of air the same size because it is denser

Song on density formula http://www.youtube.com/watch?v=VfMDC4guXZg

Density is measured in: g/cm3 kg/m3 g/mL kg/L

If each ball has the same mass, which box would weigh more? Why? The box that has more balls has more mass per unit of volume. This property of matter is called density. The density of a material helps to distinguish it from other materials. Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter.

Copper atoms are smaller than aluminum atoms. More copper atoms can fit in the cube. Copper atoms are also heavier than aluminum atoms. The combination of more and heavier atoms makes copper more dense than aluminum. Lab: What is Density? http://www.middleschoolchemistry.com/multimedia/chapter3/lesson1

Arrangement of Atoms Less dense More dense Less mass (matter) in a given volume More mass (matter) in a given volume

Mass of Individual Atoms Affects Density Some individual atoms or molecules have a greater mass than other atoms or molecules which can cause a substance to be more dense

Density of water = 1 g/cm3 or 1 g/mL

Formula: Problem: Show Work: Answer: 2. The density of water is 1 g/cm3. Will the ice cube sink or float in water?

Ice is less dense than water

Seven Layer Density Column MaterialDensity in g/cm3 or g/mL Rubbing Alcohol .79 g/cm3 Lamp Oil .80 g/cm3 Baby Oil .83 g/cm3 Vegetable Oil .92 g/cm3 IceCube .92 g/cm3 Water 1.00 g/cm3 Milk 1.03 g/cm3 Dawn Dish Soap 1.06 g/cm3 Light Corn Syrup 1.33 g/cm3 Maple Syrup 1.37 g/cm3 Honey 1.42 g/cm3

How does temperature effect density?

DMV Triangle m is the top of the mountain

Warm Up A block of aluminum occupies a volume of 15.0 mL and weighs 40.5 g. What is its density? Mercury metal is poured into a graduated cylinder that holds exactly 22.5 mL. The mercury used to fill the cylinder weighs 306 g. Calculate the density of the mercury. Use this format for both problems: Formula: Problem: Show Work: Density =

Warm Up A rectangular solid of unknown density is 5 meters long, 2 meters high and 4 meters wide. The mass of this solid is 300 grams. What is its density? Formula: Formula: Problem: Problem: Show Work: Show Work: Volume = Density =

Warm Up The density of lead is 11 g/mL. What would the volume of a 200.0 g sample of this metal be? Formula: Problem: Show Work: Density =

Taking Up Space! Volume Challenge #1 R. Bryant 2008 WSMS – Based on “Science Starters” by T. Trimpe at http://sciencespot.net

Determine the volume of this cube. 5.7 cm 5.7 cm 5.7 cm

The answer is … Volume = length x width x height l = 5.7 cm w = 5.7 cm h = 5.7 cm V = 5.7 cm x 5.7 cm x 5.7 cm V = 185.19 cm3

Sink or Float? Density #1 R. Bryant 2008 WSMS – Based on “Science Starters” by T. Trimpe at http://sciencespot.net

Find the density of the box below. Mass 456 g 12.5 cm 5.6 cm 5.6 cm

Volume = length x width x height The solution … Volume = length x width x height V = 12.5 cm x 5.6 cm x 5.6 cm V = 392 cm3 M = 456 g Density = Mass ÷ Volume D = 456 g ÷ 392 cm3 D = 1.16 g/cm3 **The box would sink!

Sink or Float? Density #2 R. Bryant 2008 WSMS – Based on “Science Starters” by T. Trimpe at http://sciencespot.net

Find the density of the box below. Mass 386 g 23.5 cm 6.4 cm 7.8 cm

Volume = length x width x height The solution … Volume = length x width x height V = 23.5 cm x 7.8 cm x 6.4 cm V = 1173.12 cm3 M = 386 g Density = Mass ÷ Volume D = 386 g ÷ 1173.12 cm3 D = 0.33 g/cm3 **The box would float!

Sink or Float? Density #3 R. Bryant 2008 WSMS – Based on “Science Starters” by T. Trimpe at http://sciencespot.net

Find the density of the object below. An object was dropped into a graduated cylinder that contained 20 mL. Determine the volume of that object. The object was placed on a triple beam balance. The mass Image from http://ritter.tea.state.tx.us/ Image from http://genchem.rutgers.edu/bal3b2.html

Volume = Volume of water & object – volume of water The solution … Volume = Volume of water & object – volume of water Volume = 43 mL – 20 mL V = 23 mL M = 373.3 g Density = Mass ÷ Volume D = 373.3 g ÷ 23 mL D = 16.23 g/mL

Sink or Float? Density #4 R. Bryant 2008 WSMS – Based on “Science Starters” by T. Trimpe at http://sciencespot.net

Find the density of the object below. The object was placed on a triple beam balance. 20 An object was dropped into a graduated cylinder that contained 40 mL. Determine the volume of that object. 5.4 Image from http://www.edinformatics.com/math_science/mass.htm

Volume = Volume of water & object – volume of water The solution … Volume = Volume of water & object – volume of water V = 65 mL – 40 mL V = 25 mL M = 25.4 g Density = Mass ÷ Volume D = 25.4 g ÷ 25 mL D = 1.01 g/mL ** The object will sink!

Eureka video on volume and density: http://www.youtube.com/watch?v=GMNpPgLT8Fk

Eureka Video on volume and density http://www.youtube.com/watch?v=GMNpPgLT8Fk Eureka Video on density and buoyancy Dr Carlson on density (displacement) http://www.youtube.com/watch?v=14nahP_FVnM