DENSITY is a physical property of matter, as each element and compound has a unique density associated with it. Density defined in a qualitative manner as the measure of the relative "heaviness" of objects with a constant volume.In other words,it is the the amount of mass per unit volume,therefore,the equation is D=M/V.D is density,M is mass and V is volume.These are some of the examples:
grams per mL | |
Some experiments to try out:
http://www.elmhurst.edu/~chm/demos/index.html-Floating Eggs
http://www.elmhurst.edu/~chm/demos/index.html-Lava Lamp
http://www.elmhurst.edu/~chm/demos/index.html-Underwater Smokestack
Vocabulary Required:
| SIGNIFICANT DIGITS | VOLUME | DENSITY |
| ACCURACY | DENSITY OF WATER | MASS |
| PRECISION | MENISCUS | DERIVED UNITS |
Displacement
When trying to measure the volume of an irregularly shaped object, the "water displacement method" is the most commonly used technique and the one you will use most often in this chemistry course. The procedure for the water displacement method is listed below.
PROCEDURE:1) Find a graduated cylinder that will be large enough to fit the object(s) being measured.
2) Fill this graduated cylinder enough so that when placed in the graduated cylinder, the object(s) in question will be fully submerged in the water. Also be careful not to put in so much water that the water level will rise past the graduated cylinder’s markings when the object(s) are placed in the graduated cylinder. You must use your own judgment to determine what amount of water meets these requirements.
3) After filling the graduated cylinder to a satisfactory level, record the volume of the water as (a) in your data. Make sure to read the meniscus when determining volume.
4) After the water’s volume has been recorded, carefully place the object(s) in the graduated cylinder and record this volume as (b) in your data.
5) In order to calculate the volume of the irregularly shaped object(s), subtract the volume of the water alone from the volume of the water and object(s) [(b) – (a)].
Hints and Tips:
1) All objects must be fully submerged when using the "water displacement method".Standard units
2) If a solid substance is soluble in water, another liquid may be substituted when using the "water displacement method".
3) Use a smaller graduated cylinder whenever possible regarding the measurement of a substance's volume. The smaller a graduated cylinder is, the more accurate your measurement can be.
4) Density of water is 1.00 g/cm3.
5) Rust is a source of error when calculating density of metals.
6) Remember to mass all objects only when dry.
The International System of Units (abbreviated SI from French: Système international d'unités) is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. It is the world's most widely used system of measurement, both in everyday commerce and in science as The International System of Units (abbreviated SI from French: Système international d'unités) is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. It is the world's most widely used system of measurement, both in everyday commerce and in science.
| Name | Unit symbol | Quantity | Typical Symbol for Variables |
|---|---|---|---|
| metre | m | length | l (a lowercase L) |
| kilogram [Notes 1] | kg | mass | m |
| second | s | time | t |
| ampere | A | electric current | I (a capital i) |
| kelvin | K | thermodynamic temperature | T |
| candela | cd | luminous intensity | Iv (a capital i with lowercase non-italicized v subscript) |
| mole | mol | amount of substance | n |
Reflections-
Firstly,I feel that that standard units are very important as they are indicators of the sample size used by scientists,other than that,it is essential that scientists over the world accepts a common unit as there are many scientists in the world and there are many discoveries that are continuously explored,if scientists use an inch or other unknown units instead of centimeters,then,their records would not be understood and developed on by other scientists.Transparency is important in the intellectual field of science today,many of the scientists work as a team on different aspects and then,comply their information to make a breakthrough.As we can see,the invention of standard units prevent the confusion and conflicts over different measurements used.
Secondly,i feel that density is something we all must know as it is an indispensable property in our liquids,gases and solids.Density clears my doubt of why certain objects sink and why some people who are taller are lighter than those who are shorter(no offense).So basically,it is another property factories have to consider before making their product.:DDD
THE END
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