VIII

Gibbs free energy is the change of G= the change of H(exothermic = H is negative, Endothermic = H is positive)- temperature the change of S. If the change in G is negative, the change will be spontaneous at the given temperature. (It is favorable). However, when the change in G is positive, the change is not spontaneous. If the change in H is positive and the change of S is negative then the reaction is not spontaneous whatever the temperature is. On the other hand,  if the change in H is negative and the change in S is positive, the reaction is spontaneous. Polymers are molecules made of long strings of monomers that are attached to each other.

Chapter VII

A chemical reaction that contains to occur on it own, once it begins is called spontaneous. Chemical reactions, are possible to control and by predicting when a reaction can occur, and how to accelerate the reaction, or to slow it down. Thermodynamics, is used to solve questions if a reaction can occur by itself. And Kinetics, is used to ask and answer how fast a reaction occurs. The main points of reactions are, is the bonds between the reactants break and new bonds form to make products? However, in order to break bonds, energy is needed and bond breaking is an endothermic change. On the other hand, making the bonds releases energy, so this is an exothermic change

 

Section VI

Electrolytes are substances that break into charged particles when dissolved in water and can conduct electricity. Non-electrolytes are molecules that do not form ions in solution and can not conduct electricity because they do not form charged particles. Two half cells make up a battery. One called anode is the one that oxidizes, and the other half-cell called cathode which does the reduction. In the lab, we used zinc and copper to put in the battery. Zinc experienced oxidation so it loses two electrons. The electrons of zinc then travel to the reducing part which is copper. The redox lets copper to continue oxidizing and 

Section V

In section 5 we learn about light. We used visible lights in our experiment. Our eyes are able to detect visible lights because of their wavelength, which is the distance between two points of a wave. All wave travel at the same speed, that is the speed of light. (3.00 x 10^8) The equation to find out the frequency is (3.00*10^8)=λ(wavelength in meters)*f(frequency). The longer the wavelength, the lower the frequency. This is also same with the energy of the light. The longer the wavelength, the lower the energy. Infrared light would have the longest wavelength but the lowest frequency and energy. Energy can be found using the equation E=h(Planck’s constant+6.63*10^-34)*f(frequency in s^-1). For an atom to emit light, its electron starts off in the ground state and needs energy for it to move up the energy level. If enough energy is given, it will reach its excited state. Fluorescence light absorbs energy, it will also release energy to its ground state right away. However, some light using a more complicated process called phosphorescence. The electron first needs to have enough energy to reach the excited state and later fall to the triplet state where it can emit light like what we saw on the glow tape. The color like blue and Ultra-Violet have the ability to emit that color because they have enough energy. 

Chem talk

In the lab, we turned a LED on and off by using metals. We used a metal to turn off the glowing LED light. 

Metals can conduct electricities, so they are used in electrical circuits, plus can conduct heat, so they are used in kitchens or cookwares, they are also used to build strong structures because they can be shaped into different shapes. 

Many metals are reacted with hydrogen and are founded in nature. Positively charged ions are involved in solid crystals or dissolved in water.When an atom reacts with another in the metal, the electrons that are placed in the metals are changed.

Oxidation-reduction reaction is a reaction that occurs between neutral metal atoms and metal ions. Oxidation = losing electron, and receiving electron = Reduction. 

 

section 3 chem 2 go~

 

  • a. CO2. b. came from the carbonated water after heated up. c. Yes. d. Yes.
  • NaHCO3(23+1+12+16*3=84)+ HC2H3O2(1+2*12+3+16*2=60)→NaC2H3O2(23+2*12+3+2*16=82)+H2O(1+2*16=33)+CO2(12+2*16=44)  84+60=144  82+33+44=159
  • a. 12g. b. 27g. c. 14+1*3=17 d. 40+12+16*3=71 e. 23+27+2(32+16*4)=242
  • a. 18/12=2.5 b. 27*0.5=13.5 c. 17*2.84=48.28 d. 10.0/71=0.14 e. 49.5/242=0.20
  • a. (L)K: 2  CI:2 O:6.  (R) K:2 CI:2 O:6. b. (L)2*40+2*35+16*6=246 (R)2*40+2+35+16*6=246 c. 1
  • a. 1 b. 12+16*2 = 44g c. 2g d. 4g
  • a. 0.025 mole 

 

Stoiciometry

The measurement molecules are called moles and how to calculate moles and the number molecules we need for a reaction to occur. The molar mass is written under the acronym of each atom. Balancing equation is also related to moles. We need to make sure each molecule or element has the same mole on both sides of the equation. If not, we need to add coefficient in front of the molecules or elements to help them balance. It is important to calculate mole in STP (standard temperature and pressure) when it comes to liquid and gas. It is important to make sure equation is able to cancel things out and left with the unit you want at last. This calculation is called the dimensional analysis. Rarely in the experiment, some products were found missing. This is why scientists came up with the percent yield method to figure out what is the original amount of product.

CH4. Section 1 Chem talk

In Gibbs free energy and energy either get released or absorbed by substances. when energy is released, it goes to the molecules making the particles get faster or into the bond of the molecules. On the other hand, a bond is not an attraction force. Bond exists in molecules but attraction force exists in between two or more molecules. An attraction force is weaker than a bond. But they both require energy to break it. If the energy change from start to finish is positive, meaning we gained energy during the process, it’s called endothermic. However, when energy changes from start to finish are negative, so when we lost or released energy during the process, it’s called an exothermic change. 

P.S.

We can say that its disorder increases when gas goes to liquid then to solid. The amount of disorder we measured is called entropy and entropy increases by solid<liquid<aquious solution< gas. 

chem to go ch4. section 1

1. a. exothermic   b. endothermic    c. exothermic

2. a. increases.     b. decreases.          c. increases

3. For the first equation:

      a. Product =2Fe2O3(s) Reactants = 4Fes+3O2         

      b. Solid molecules have the strongest atomic orginization that keeps its form. 

2nd Equation

      a. Product = 2KClO3, Reactants = 2KCl + 3O2 

      b. Since the molecules gets stronger so it gets more disordered.

4. exothermic, A

5. B

6. A

Chem Talk 7

In dye, we need a dye molecule called a chromophore to have the color we actually see. The reason why we can see colors are due to that the chromophores are able to absorb visual lights. Mordents are also very important in dyeing things. Mordent helps the dye to stick and keep the color. For example, we used a string to make the dye get in and the string works as a mordent.