Density

Density Demonstrations

• What did you learn from the density column demonstration?

• Liquids have differingdensities

• Liquids form layers dueto density

Density Demonstrations

• What did you learn from the lemon-lime demonstration?

• Lemon density = 1.02 g/cm3 • Lime density = 1.12 g/cm3

• Density of water = 1 g/cm3

Lemons float, Limes sink

• Density of limes and lemons are VERY close

• They were cut, peeled, and juiced during the experiment

• Therefore, a TINY change in the composition can make the difference between floating or sinking!

• Not all science experiments go according to plan!!!!

Density Bingo!!

• We will play BINGO using the density problems on today’s assignment

• You can refer to your assignment during the game

• Put any of these numbers ANYWHERE on your BINGO card – your choice… what’s your strategy??

Of course, it’s Earth Science

• Instead of BINGO, we will play NEON

• This makes a 4 x 4 card• We’ll do variations also – like four

corners, postage stamp (four in the upper right corner), all in the middle (four in the middle)

Fill in your NEON card

• 0.670 g/cm3

• 7.31 g/cm3

• 0.00014 g/cm3

• 0.35 cm3

• 400 g• 11 g/cm3

• 3.26 g/cm3

• Above 1 g/cm3

• 500 g• 36 cm3

• Below 1 g/cm3

• 1 g/cm3

• Sinks• Floats• D=m/v• Freebie

Rules & Regulations

1. I will read a density problem (from assign)2. You will work out the problem (notebook)3. Then, mark that square on your board4. If you don’t have that answer on any

square, double check your work!1. Calculation correct? Sig figs correct?

5. You can look back at your assignment if your work is done on there – you don’t have to REDO the work if it’s done already

Problems:

• What is the equation that you ALWAYS write at the beginning of a density problem?

• D = mass/volume (D = m/v)

• You must ALWAYS show the equation you use when doing problems!!!

Problems:

• A piece of tin has a mass of 16.52 g and a volume of 2.26cm3.

• What is the density of tin?

• D= m/v

• D = 16.52g / 2.26cm3

• D = 7.3097… (how many sig figs?)

• D = 7.31 g/cm3

Problems:

• A man has a 50.0 cm3 bottle completely filled with 163 g of a slimy green liquid.

• What’s the density of the liquid?

• D = m/v

• D = 163 g / 50.0 cm3

• D = 3.26 (how many sig figs?)

• D = 3.26 g/cm3

Problems:

• A sealed 2500 3 flask is full to capacity with 0.36 g of a substance.

• Determine the density of the substance.

• D = m/v

• D = 0.36 g / 2500 cm3

• D = 0.000144 (how many sig figs?)

• D = 0.00014 g/cm3

Problems:

• A piece of metal has a volume of 6.7 cm3 and a mass of 75.7 g.

• Find the metal’s density.

• D = m/v

• D = 75.7 g / 6.7 cm3

• D = 11.298507… (how many sig figs?)

• D = 11 g/cm3

Problems:

• The mass of a 125 cm3 piece of material is 83.75 g.

• Determine the density of the metal.

• D = m/v

• D = 83.75 g / 125 cm3

• D = 0.67 (how many sig figs????)

• D = 0.670 g/cm3

Problems:• What is the mass of an object that has a

density of 8 g/cm3 and a volume of 64 cm3?

• D = m/v• 8 g/cm3 = m / 64cm3

• How do we get “m” by itself?• (64) (8) = m• m = 512 (how many sig figs?)• m = 500 g

Problems:

• Different kinds of wood have different densities. The density of pine is generally about 0.5 g/cm3. What is the mass of a 800 cm3 piece of pine?

• D = m/v• 0.5 g/cm3 = m / 800cm3 (Get ‘m’ by itself)• (800)(0.5) = m• 400 = m (how many sig figs?)• 400 g

Problems:

• What is the volume of 325 grams of metal with a density of 9.0 g/cm3?

• D = m/v

• 9.0 = 325 / v (get ‘v’ by itself, in the numerator)

Problems:

• Diamonds have a density of 3.5 g/cm3. How big is a diamond that has a mass of 0.10 g?

• D = m/v

• 3.5 g/cm3 = 0.10 g / v (get ‘v’ by itself, in the numerator)

Problems:

• What is the density of water?

• 1 g/cm3

• What would happen to the objects if thrown in water, for #1, 2, 4, 6, 8, 9?

• They FLOAT

• How do you know they float?

• Density is BELOW 1g/cm3

Problems:

• What would happen to the objects in #3, 5, 7 if we threw them into water?

• They SINK

• Why?

• Their density is ABOVE 1 g/cm3

Another Science Project!

• Why do some pop cans float, but some sink?

• The cans are the same material, same shape, size and weight

• http://www.stevespanglerscience.com/experiment/floating-lemons-and-sinking-limes#review