Density Lesson
o OVERVIEW:
o This activity is designed to familiarize students with the use
ratios as well as a general review of the scientific method.
o Appropriate for any level science class.
o PURPOSE:
o One of the most important skills for the science student to
develop is the ability to understand ratios.
o OBJECTIVES (The student will be able to):
o Gain a sense for some of the more common examples of
ratios such as density.
o Begin to develop an idea of basic metric units as a tool to
make objective measurements in the real world.
o Learn techniques for translating one type of units into
another type of units.
o ACTIVITIES:
o COLLECT HOMEWORK
o PRE-LAB:
o The scientific method:
o Students are prompted to draw their own picture of the scientific
apparatus showing an explanation of the color change and
volume change witnessed. After the full scientific method is
used to explore the possibilities, the siphon and food coloring is
revealed.
o The principle behind the siphon will then be explained in terms
of the ratio between Force and Volume (pressure equals “rho”
times “g” times “h”)
o Examples of how such siphons may be useful.
 Drinking water from tanks
 Anti-siphon Valve
 Circulatory System- the heart
 Steal Gas
 Romans - Pb - lead - Plumbus (plumber, lead
poisoning-crazy Roman heirarchy theory
o Which stream of water will travel the furthest activity?
 Pressure = force divided by area.
o Cloud maker consisting of isopropyl alcohol and pump.
o Where do clouds form?
 Air Pressure
 Elevation
o Health applications
 Altitude sickness lawsuits - common when people are
sick...
 Scuba diving
 Children’s ear infections.
 Tubing from ear next to Central Nervous System.
o Which will float and sink? (Diet vs. real 7up).
 Density = mass / volume ( more sugar regular 7up )
 Try to make 7up float.
o Moon’s Marra’s or Craters darker denser rock.
 Same rock at bottom of oceans - more density, rock sinks Granitic rock vs. Basaltic rock.
o Liquid: Vegetable oil, water with food coloring in a 2 liter bottle.
 Which is granitic, which is basaltic?
 Density = mass/volume(ratio)
o Gases: pour out candle using vinegar and baking soda.
 NAHCO3 + C2H3OH yields CO2
 Density = mass / volume ( a ratio )
o Catch bubbles with beaker game (middle schoolers)
 Why C02 denser (periodic table)
 CO2 (MW = 44) vs. air (N2 and O2 mostly, MW = 28 and 32)
o Hydrogen sulfide gas
o Disaster in Camaroon story of the hospital and town.
o Fire in a house, flame symbolizes respiration
o Burn hydrocarbons yields CO2 and H2O
o Burn sugars yields CO02 and H2O
o Counter-intuitive floating objects
 Pumice stone.
 Eye dropper inside 2L bottle. Make dropper follow hand.
 Explain in terms of 4 forces.
 Squeezing changes density of system, causes dropper to
displace less water, negative buoyancy
 Archimedes principle: an object is buoyed up by a weight
equivalent to the weight of the fluid displaced.
o Steel boats - picture
o Basketball to bottom of a pool
o Beach ball
o Why? More water pushed out of the way.
o RESOURCES:
o 5 2 liter bottles, food coloring, hand pump, flask, stopper,
basaltic- granitic rock, vinegar, baking soda, eye dropper,
pumice stone aluminum foil, nails, tubing, isopropyl alcohol,
diet 7up can, regular 7up can, candle.