When speaking of change, chemists refer to the system and the surroundings. Together, the system and the surroundings make up the universe. You choose the system that you want to investigate and you can imagine drawing a dashed surface around the system, to separate it from the surroundings.When considering change you think about what the system is doing. When we stretched the rubber band we asked is it producing heat energy or releasing heat energy. If the system is an open system, energy can pass between the system and the surroundings. For example a teakettle heating on the stove is an open system. A closed system is a system that is isolated form the surroundings and heat can neither enter nor leave. This is very, very difficult to achieve. An attempt at a closed or isolated system is a thermos bottle. As we know a thermos bottle slow the movement of heat, but eventually the hot soup or cold beverage in the thermos bottle will exchange heat with the surroundings. This is my last chem talk and i can’t describe the feeling i am feeling right now. It is a bittersweet feeling.
In this section we explore a chemical reaction that continues to occur on its own once it begins. This reaction is spontaneous. In a case of a reaction that produces heat energy, controlling the speed of the reaction will let you control how quickly heat is produced. For chemists and engineers to be able to control chemical reactions, they must be able to predict when reactions can occur spontaneously, and also what can be done to speed up or slow down reactions. One set of theories called thermodynamics is used to answer the question Can a reaction occur spontaneously? A second set of theories called kinetics is used to answer the question How fast can a reaction occur? Together, thermodynamics and kinetics help chemists and engineers to design reaction and processes that impact everyone’s lives. There are two factors that determine if a change can occur spontaneously. The first factor that affects spontaneity is if the changes gives off heat energy when it occurs or absorbs heat energy when it occurs. The second factor that affects spontaneity is if the change results in particles becoming more disordered or less disordered. Two commonsense rules apply to these two questions. First, lower energies are more stable than higher energies. So, in the same way that a ball tends to roll downhill, energy changes in chemical reactions tend to occur in ways that allow the substances to end up with lower energy. This means that changes that release energy tend to be favored. Second, everything tends to become more disorganized over time, so the changes in which particles become mire disordered are favored over those that make particles become more ordered.
Substances that dissolve in water to make solutions that conduct electricity are called electrolytes. In this invention we used a conductivity tester to determine if a solution conducted electricity. For any solution to be able to conduct electricity, it must contain charged particles that are able to move. Al the solutions we tested were made of substances that were dissolved in distilled water. For a solution to conduct electricity, there are two things that must happen. Charged particles must be present and the charged particles must be able to move around. Some compounds dissolve in water to form charged particles called ions. For example table salt, sodium chloride is made of sodium ions with charges of +l and the chloride ions (Cl-) separate from the crystal and are surrounded by water molecules. Since the ions are surrounded by water, they can move about in the water. Since there are charged particles that can move, a solution of sodium chloride is able to conduct electricity.
The lab we did yesterday was all about visible light, energy, and the electromagnetic spectrum. We examined the colors that make up visible light and used LEDs to explore a glow-in-the-dark star. Light is a form of energy known as electromagnetic radiation. Electromagnetic radiation includes X-rays, ultraviolet (UV) rays, microwaves, and radio waves in addition to visible light. As we saw in the lab we could see visible light with our eyes, but we can not see the electromagnetic radiation with our eyes. I wish my super power was to electromagnetic radiation because that would be wicked cool! Light can be characterized by its wavelength and its energy. The wavelength of light is the distance between two corresponding points of a wave. Wavelength is measured in nanometers. A nanometer is one-billionth of a meter. Gamma rays have the shortest wavelength and radio waves have the longest wave length. In the lab we worked with visible light that had the wave length of 400 nm to 700 nm. Visible Light sits in-between Ultra-violet light and Infrared Light in the Electromagnetic spectrum. This lab was very interesting and it taught me a lot about light and what super power would be cool to have.
Metals are very shiny. Some may say they are as shiny as Mr. Dougan’s head. Metals also conduct electricity and are used in electrical circuits. They conduct heat so they are also used in cookware. Metals can also withstand high temperatures, so they are used to build strong structures. Most elements in the periodic table are metals. The majority of metals are more reactive than hydrogen and are more commonly found in nature in their ironic forms, as positively charged ions involved in solid crystals or dissolved in water. Some metals react more easily with most metal ion solutions than other metals do. The reactions that can occur between neutral metal atoms are part of a special class of reactions called oxidation-reduction reaction. Our lab was all about how metals reaction during an oxidation-reduction reaction
This lab was all about dominos. Not the pizza Dominos tho, like actual dominos. P.S. i prefer Pizza Hut over Dominos. A mole is a counting word used to count very large quantities of very small objects. 1 mol = 6.022 x 10^23. However in this lab, the actual number did not matter very much. What was most important was that one mole of anything is always the same quantity. Three moles of something is three times as much as one mole. One mole of any single kind of atom or molecule has a mass equal to its atomic or molecular mass expressed in grams.
In this lab, we generated CO2 gas and used that gas to blow up a balloon and move a lever. Each production method used different materials and generated a different amount of gas in a different amount of time. When matter undergoes a change, there often is a change in energy involved. When my group did the lab we used baking soda and vinegar. We used .5 grams of baking soda and .4 mL of vinegar to get the balloon to blow up to 6 cms. This was definetely a super cool lab and it showed our ability to work as a group! I grade this lab a 11 out of ten!!!
Ive always been fascinated by colors since i was very little. Colors are unique and bring perspective into life. In this lab we worked with putting yarn in heated tea and then dropping it in water and then taking it out. It was one of the more easier labs but the outcomes were really cool. The art of dyes comes from organic molecules that bond directly to a textile to produce a color. Since they are tightly bound to the material, they do not wash out like the early coloring agents did. One chemical feature of a dye mole that make it useful as a dye is the chromophore. The chromophore is that part of the dye molecule responsible for the color you see. Another chemical feature of a dye that make it useful as a dye is the auxochrome. The auxochrome will modify the chromophore’s ability to absorb light energy. Well the lab was cool but this chem talk was cooler 😉
The solid precipitates we observed in the investigation are insoluble compounds. They can be used as pigments for paints. If the pigment is insoluble in the liquid, it will become a suspension of particles in the liquid. When the paint dries, the pigment particles are left behind. So i guess you can say that finding pigment particles is like watching paint dry….lol. There are thousands upon thousands reactions that occur in the world, and most of them take place in water solutions. When certain cations and anions are combined, water-insoluble ionic compounds may form. When we did this lab we discovered that the egg white was the best for mixing paint and water was a close second.