Have you ever marvelled that the many colors of fireworks? How do fireworks makers get these colors? The answer iies in the chemistry and electron configurations of some elements.
Highly reactive metals, such as potassium, have a very loosely bound outer electron. It takes little energy to bump it from its ground state into an excited state. It will then drop back down into lower-energy states. Which states depend on rules that are beyond this discussion.
Conservation of energy demands that something happen to the electron's energy when it drops into a lower-energy state. Because the electron has a charge, it can emit electromagnetic radiation. If the energy is in the right range, those photons are visible light.
Different elements have electrons with different energy levels and so make different colors of iight. The fireworks manufacturers know which elements make which colors and combine them skllfully to make the remarkable colors of their product in the sky.
Salt and sugar are soluble in water. Oil is insoluble in water. When small amounts of a substance dissolve, the substance is termed slightly soluble.
The water in the above cases is known as the solvent, which does the dissolving. The salt, sugar, and oil are the solutes, the stuff you're attempting to dissolve.
You'll see attempts to dissolve a number of solutes, both solid and liquid, in liquids. See the Procedure page for information on the chemical composition of all of these substances. Make predictions before each experiment.
Look for ways to predict solubility. Note the size, mass, composition and polarity of the substances. Polarity refers to the amount of separation of electrical charge in a molecule. Higher dielectric constant means greater polarity.
The neck's calibrations show 0.1 ml per large calibration mark and 10 microliters (μl) for the smaller marks. Microliters are 1,000 times smaller than milliliters.Some analog measurements are listed below.
Length: meter stick
Mass: triple-beam balance
Force: spring scale
Volume: graduated cylinder
In this lab, you'll measure distance, mass, temperature, force, and volume.
Any measurement consists of two parts:
the value and
If you report a length as being 1.7, no one will know whether it's the size of a bacterium or a continent. Don't leave out the units.
Accuracy tells how good your measuring device is.
Does it measure correctly?
Precision is all about repeating measurements and getting the same value.
Try to measure the height of someone who won't stand still.