Use an element's atomic weight to determine how much weight each atom of the element is. Aluminum has an atomic weight of 26.9815 in Daltons or grams per mole (g/mol). This means if you have a certain number of moles of aluminum, you can multiply it by the atomic weight to figure out how many grams per mole of aluminum you have.
This accounts for the weight of aluminum in its pure form. This type of aluminum weight doesn't include any other elements that may be mixed in with it or that are contaminating it. In practice, many uses of aluminum use it as an alloy. This means that they use metal objects that contain aluminum alongside other elements such as copper or iron.
Weight and Mass
You can make straightforward measurements of weight by placing a substance on a scale or balance. Depending on the type of scale or balance you're using, you will get an output in either mass or weight. You should also take into account the weight or mass of the container you're using to weigh the aluminum sample.
If you have a certain mass that you would like to convert to weight, you can use the weight equation W = mg for weight W, mass m and gravitational constant g of 9.8 m/s2. Keep in mind this gives the weight in newtons for a mass in kilograms. To convert from newtons to pounds, you multiply the weight in newtons by 0.2248.
You derive this equation from Newton's second law, F = ma for a force F and acceleration a. In the case of an object's own weight, the force is the gravitational force between the object and the Earth.
Online Weight Calculator
Several online calculators exist for calculating the weight of metals such as aluminum. The weight calculator from OnlineMetals.com lets you figure out the weight based on how the metal was manufactured and the shape of the metal object itself.
You can use calculators like this one for practical purposes of estimating how heavy certain metal elements may be. Ensure you account for the appropriate shape and components of the metal you want to weigh.
Mechanical Advantage of Aluminum
You can also test simple machines like wedges or pulleys made of aluminum for their efficiency in using forces you apply to them. The more efficient these machines are in using the force applied to them, the higher their mechanical advantage is. These machines like pulleys or levers have an ideal mechanical advantage (IMA), or the ratio of the force they output to the force applied to them.
An ideal mechanical advantage formula is F0/Fi for the output force Fo to input force Fi. Different alloys of aluminum have different mechanical properties, leading to differences in mechanical advantage.
You can also mesaure the ideal mechanical advantage as do/di _for the output distance _do over which the force is exerted, and the input distance di. This would equal the distance you pull one rope of a pulley or the distance a lever travels when used as a simple machine.
This works because, according to conservation of energy, the work put into a system equals the work the system exerts. Work is the product of force and distance. If Wi = Wo for input work Wi and output work Wo and IMA = F0/Fi, then Fo x do = Fi x di and IMA = do/di.