Mass |
|
Density = |
----------- |
Volume |
Now, we know how to get the density of Lead, it is simply the mass of the object divided by the volume of water that it displaces. In our case, we use the weight lost, when weighing it in water, and use that value of grams to be equivalent to millimeters. And density is expressed as grams divided by millimeters or grams divided by cubic centimeters.
Now, Specific gravity is simply a RATIO of the Density of an object to the Density of our standard, which is water . If you were to set up that ratio, algebraically all the units would cancel out, and you would be just left with a number and no units.
Where to get your Al, Cu, and Fe any place that you can, use your imagination, here are some places that you can use. For iron, you could use large nuts and bults, for Aluminum you can use Aluminum wire, from hardware store, from chain link fence company, they have Aluminum wire wrap, that is used to attach the chain link fence to the pipe. You can also find old Aluminum pots and Aluminum chairs, where you can cut a four inch section. For Copper, the hardware store would be a good place, now you could barrow a piece of Copper plumbing, a coupler or a right angle, a piece of old Copper pipe, and lastly you could use Copper wire, 10, 12, or 14 gauge Copper wire, but first remove the insulation. Make sure that it is Copper and not Aluminum wire Copper clad.
Now, lets take a closer look at out samples that we are going to be working with. Our samples can be considered as pure substances, a pure substance can be considered as being composed of one kind of atom, in that case it would qualify as being an element, now water is also a pure substance but in this case it is made of two hydrogen atoms and one oxygen atom, so a pure substance made up of two or more different atoms is classified as a compound, so when we refer to the smallest particle of an element it would be an atom, and still have all the properties of that element. Water on the other hand you have to say that the smallest particle of that pure substance would have to be a molecule and still have all the properties of that compound. The air that we breath is composed of about 21 percent Oxygen, it too is a pure substance, how ever the smallest particle of Oxygen would not be an atom but a molecule, that is because Oxygen atoms travel in pairs. The greater part of air about 78 percent is made up of Nitrogen, that also exists as a diatomic molecule or two molecules traveling in a pair. The air that we breath is really a mixture of two or more substances, having the same composition through out, in that case it is considered as a homogeneous mixture.
For one thing, all matter has Physical properties that help identify it, properties that can be recognized with our senses, are Qualitative Physical Properties, our substances in this case are all metals, in general metals are heavier or more dense then non metals; good conductors of heat and electricity, are ductile, that is they can be drawn in to wire, malleable, rolled or flattened into sheets, most are shiny or can be polished to a high degree.
| Color | oder | taste | Crystile form | Physical state | |
| Al | X | ||||
| Cu | X | ||||
| Fe | X | ||||
| Pb | X |
Now matter also has QUANTITATIVE PHYSICAL PROPERTIES, these are properties that be quantified with a number. That is using a number to help identify it, such as quantitative physical properties of water, water is the only substance that would have these quantitative physical properties; the density of water is 1 gram / millimeter, it has a melting point of 0 ° Celsius, it has a boiling point of 100 ° Celsius, at sea level. Now, Al, Cu, Fe and Pb will also have quantitative properties.
Density |
Hardness | Boiling Point | Melting Point | Solubility | |
| Al | 2.70 g/cm3 | 660 ° C | 2057 ° C | ||
| Cu | 8.9 g/cm3 | 1083 ° C | 2336 ° C | ||
| Fe | 7.86 g/cm3 | 1535 ° C | 3000 ° C | ||
| Pb | 11.34 g/cm3 | 327 ° C | 1620 ° C |
OBJECT:
To find the Specific Gravity of Aluminum, Copper and Iron.
MATERIALS:
Samples of Aluminum, Copper ( note; do not use pennies )and Iron, Monofilament thread or very thin thread, SBB, One gallon plastic container.
PROCEDURE:
1. Obtain the approximate weight of the Samples, with the "First class lever " in Lab # 2, and record them on paper.
2. Zero balance your SBB, and obtain the exact weight of each sample. If possible write the value on the sample with a fine point magic marker.
3. Approximate the distance to the water. Make a loop at the end of the thread, gently slip the loop on to the paper clip supporting the plastic cup, on the left side. Gently slip the object that you are weighing into the plastic container, and record it's weight in the table ( chart below ).
4. If you find that the thread is to long, you can shorten it by making a knotted loop in the middle of the thread, but first detach it from the SBB, so the SBB wont tilt over.
5. Repeat the above procedure for each object, and record the exact weight.
6. Get your calculator, or use the one on Windows 95 or 98 and compute the results, and record them .
7. Loss of weight, would be the amount of millimeters, that the object displaced. Use this value as millimeters for your formula, and remeber that one millimeter is equal to one cubic centimeter. ( 1 ml = 1 cc or 1cm3 )
OBSERVATION:
| Weight in air | Weight in water | Loss of weight | Density | Specifc Gravity |
|
| Al | |||||
| Cu | |||||
| Fe | |||||
| Pb |
QUESTIONS:
1. What is the per cent error for each sample.
2. Find out what is the relationship between Copper and Zinc and Brass.
3. Find out what is the relationship between Copper and Tin and Bronze.
4. What are some of the characteristics that help differentiate between Bronze and Brass.
5. Find out what is the composition of solder .
6. Find one Bible verse that makes reference to soldering ( spelled sodering ).
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