This Chemistry talk was about Entropy and Enthalpy Changes in Rubber Bands. When speaking about of a change, chemists rear to the systems refer to the systems and the surroundings. Systems are the part of the universe under study. The surroundings are all the other parts of the universe that are not being studied. You need to evaluate what the system is doing: is the enthalpy increasing or decreasing? There are two types of systems: open and closed.
Whenever a change happens the particles rea-rrange. A change either happens spontaneously or not. If both factors change in the direction that favors spontaneity, the reaction will definitely be spontaneous. Gibbs free energy is a combination of the change in H, S, and T that is used to determine if a change is spontaneous at a a given temperature.
We learned about polymers a while ago and they are introduced into this section too. They explain rubber bands as being molecules made of long string of monomers which is a small repeating molecule.
- A reaction that continues after it begins.
2. “Will it continue to occur?” and “How fast will it occur?”
3. A bond being broken need energy is endothermic. A forming bond releases energy and that is exothermic.
4. the bonds keeping the atoms together.
5. Powdered iron, magnesium and salt water were used to increase the reaction time in a MRE heater.
6. A catalyst is a substance that provides a lower energy path way for a reaction which increases the speed of a reaction. it is not consumed (used up) during the reaction.
7. When using a catalyst the energy starts off higher, but in the end the become negative (slope) from gradually losing energy
this chem talk is about Enthalpy: Exothermic and Endothermic reactions. There are 2 important questions that will be frequently asked in this section: Will it continue? and How fast will it occur?. A change that, once begun, continues without an input of energy is Spontaneous. A chemist can know if a reaction will be spontaneous by testing it. they can also slow down or speed up the reactions. A theory called kinetics can be used to study the reaction rates and how they can be affected by variables such as concentration, partial size, and temp.
how spontaneous something relies on the factors, whether one is favorable or not. There is a chemical reaction that shows a reaction between Mg and water and the bullet point under it describe it. One of the points made is, “When chemical reactions happen, bonds in the reactants (starting materials) break, and new bonds form to make products (ending materials)” (Active Chemistry).
Our lab was based on electrodes, conductivity and solutions and how they react when they come into contact with different materials and charges. Electrolytes are substances that dissolve in h20 to make it conduct electricity. For a solution to be able to conduct electricity it must contain particles that can move around and react. ions are formed by dissolved compounds. The half cell where Oxidation occurs in the Anode while the other half where Reduction occurs is called the Cathode. Both are not able to exist without the other, they rely on one another.
Oxidation is the giving up of electrons and Reduction is the receiving of electrons. As Oxidation happens a Reduction also occurs simultaneously.
Today in class we learned about the activity series by doing a lab with our groups. In this section of the Chem. Talk it talks about the circuit Back in the day alchemist experimented with different metals, trying to see which ones could create one of the most expensive metals,gold. Gold is so sought after because it can be incorporated in Jewelry and since it does not react with outside chemicals or substances it is wearable in all aspects of life. Its ability to stay shiny and new is priceless. the alchemist in the chem talk discovered that some metals react easier with most metal ion solutions than other metals do. We also knew this from our chart in the text book that we looked at in class and copied in our notebooks using the chart we were able to identify how to format the equations between different elements and what the reactants would be.
This chem talk is titled Stoichiometry: How much gas is produced?
Stoichiometry is related to several areas of chemistry. We have studied moles as counting numbers before, they are again brought back in section 4.3. A mole is used to count large quantities. Three moles of something is three times as much as one mole. Each mole has a mass equal to its atomic or molecular mass. balanced equations are also a part of this section. One mole of almost any gas at standard temp. and pressure (STP) will occupy the same volume. Standard pressure is around the same pressure where i live and we live. Stoichiometry is the study of the relationships (mass-vol.) among substances involved in chemical reactions. In this section different units are converting to other units which involves cancelling, which we kind of did for our first section in the Fall.
1.) The molecular polarity is signals a separation of electric charges between atoms that are attracted to a molecule.
2.) London dispersions are the weak intermolecular forces that causes the electrons of an atom or molecule to shift slightly to form a temporary dipole moment.
Chem to go #6
This chem talk is on Intermolecular forces vs. Kinetic Molecular Motion. Intermolecular forces are the attractive forces acting between molecules. In class we spoke about Molecular Geometry and Electron geometry. We also spoke about Polarities. A polar bond is the difference in electronegativity of neighboring atoms causes the electrons to be attracted more to one of the atoms of the bond,making one atom slightly neg. and other slightly pos.. Electronegativity is the ability of an atom of an element to attract electrons in a chemical bond. In class we learned how to depict Molecular Geometry and Electron geometry of models. A molecule can have different types of labels based on bonded and unbounded pairs of the molecule. But when all atoms are paired they have the same Electron and molecular label.
So we have started something new! We are now building the models instead of just drawing the structures. This really helps with my understanding of the information because I am a visual person. The chemical structure is important in understanding new and known compounds. Isomers are compounds that have the same chemical formulas but different structural formulas. A hydrocarbon in which all carbons have single bonds is called a saturated hydrocarbon. An unsaturated hydrocarbon contains one or more carbon-carbon double or triple bonds. All carbon atoms have four bonds. In class we have been drawing our own lewis dot structures and it basically shows only the outer shell valence electrons following the octet rule which signifies that most elements need 8 valence electrons to be stable.
Ok so just noticed that we have to tap about class that is in bold or below
- We worked with models and building them in class which helped us see what they would look like in 3-D form
- We learned different names for different types of arrangements
- we made single and double bonds
- We learned how to match the degree of separation to the compound
Many reactions take place in water which is considered an aqueous solution. When Cations (+) and ions are combined a soluble ionic compound can form. A precipitate is formed when two aqueous solutions mix and create a cloud like appearance. In our lab we came a across a couple precipitates which turned partly solid, while others did not create a precipitate. Our lab was aimed at figuring out which mixture would be precipitates or not.