Difficulties with Volume
But there are a few small difficulties that deserve our attention:
- Consider if a volume chances...
- if material is added.
- if material is removed.
- if the amount of material is unchanged.
- Because volume changes proportional to the amount of material, volume is generally the most convenient method of measuring the quantity of materials. In the future we can expect milk to continue to be sold by the half gallon, soda by the liter, and lubricating oil by the quart. Keep your graduated cylinder handy. It will be used often.
- Consider if volume chances...
- when a substance is heated or cooled. Generally materials reversibly swell when heated.
- when material changes state (solid, liquid, gas).
- when two substances dissolve of separate.
- when a chemical reaction occurs.
- Because of these potential changes we will want to be judicious of measuring volume.
You may have heard that in 2002 a restored antique Boeing 303 airliner still carrying 50 gallons of fuel ditched into Puget Sound when the engines quit for lack of fuel. The inability of transferring all of a volume from one location to another often creates problems. When doing experiments, we will need to remember this difficulty and seek ways to avoid measurement errors with this cause.
This experiment investigates the precision of volume measurements under different physical conditions.
- Place three drops of water in a rubber balloon and seal the neck with a knot.
- Heat the water and balloon in a microwave oven for one minute. Two Cautions: Wear eye protection such as safety goggles. Steam contains a large amounts of heat and can cause severe burns. Do not touch or otherwise cause the balloon to puncture while it is inflated.
- Estimate the volume of the water before and after heating. How precise is volume as a measure of the water in the balloon?
Record your results in your science journal and write a formal report to earn credit.
Alternate or additional Experiments 1-3
Other changes in volume occur when a solid dissolves in a liquid, or two liquids dissolve in each other. Investigate using a long, clear tube with both ends blocked. Caution: Wear safety goggles.