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Density. Density Demonstrations. What did you learn from the density column demonstration? Liquids have differing densities Liquids form layers due to density. Density Demonstrations. What did you learn from the lemon-lime demonstration? Lemon density = 1.02 g/cm 3
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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)
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 Fill in your NEON card
Rules & Regulations • I will read a density problem (from assign) • You will work out the problem (notebook) • Then, mark that square on your board • If you don’t have that answer on any square, double check your work! • Calculation correct? Sig figs correct? • 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