End of the year blog

   Overall this year I enjoyed all the labs we did because I got to work with my friends and have a good time, but the unit I liked the most was the chemical reaction unit because it was fun to create chemical reactions and see what happens. Something I learned this year that I think will help me in the future is learning to take things a step at a time and not to rush when your doing something because you will miss the big picture like in the labs. The thing you did as a teacher that I found the most helpful that most other teacher I find don't do as often as you do is really go over stuff with us making sure we understand it and not just put the answers up and leave us alone.  Something that you could of done differently is... I really cant think of anything that I would change about the class so nothing :). The time in the classroom when I felt I was learning the most was when you would do an example of something in front of us and go though and say what you were doing and what was going on at the time, for example when you did elephants toothpaste. One thing I would do more is more projects because I think that really makes kids discover more about what their learning rather than just memorizing facts that they will forget the next day. When I switched from Mr.Kozmas to you this year I was a little nervous having a new teacher but the first day I felt very comfortable and I really enjoyed the experience I had in your class this year :).

Solutions to Reactions

        This week in chemistry we learned all about solutions and reaction rates. Solutions take a lot of practice to get them just right. The first thing you need to know about solutions is the difference between a solute and a solvent. A solute is the substance being dissolved and the solvent is the substance that does the dissolving. We learned that there are different factors that have to take place in order for a reaction to take place. One of the three is called agitation which is when you stir/shake the solution to produce more collisions between the particles. The second is to create a smaller particle size; this means creating greater surface area to allow more collisions for faster dissolving. The last is to increase the temperature, this increases the force and frequency of the collisions between the solvent and solute. There are also three kinds of solubility, the amount of substance that will dissolve in a solvent. Unsaturated solution is when more solute can be dissolved, saturated solutions is when the maximum amount of solute dissolved in a specific amount of solvent, and supersaturated solutions is when the solution contains more dissolved solute than a saturated solution, this is also a very unstable solution. Concentration is the amount of solute dissolved in a specific amount of solvent or solution. We measure of concentration by dividing the moles of solution by the liters of solution. There is also another formula for dilutions that is M1V1=M2V2, this is used to find the dilutions.

      Reaction Rates have many rules to get them just right. The reaction rate of a chemical reaction is the amount of product formed or the amount of reactant per unit of time. For a reaction to happen there needs to kinetic energy and the collision theory need to take place. Kinetics is reaction rates, how reaction rates change under varying conditions and what happens on the particle level. The collision theory has three rules there needs to be a collision, the substances must collide in the correct orientation, and the substances must collide with sufficient energy. High Ea, energy, has few collisions and low Ea has more collisions. There are many parts of a energy diagram that you should memorize. You should remember that reactants are at the beginning of the energy chart and products are at the end. AC is at the top of the hill of the energy chart, Ea is what the reactants have to overcome to become products, and Q is telling whether the energy chart is positive or negative.

      In the dilutions lab we started by doing the math to figure out how many grams of the CuSo4 we need to have and we did this by using the concentration formula. After found this out we filled out big flask half way with water and poured the solution in. We shook the flask till the solvent was completely dissolved. When it was completely dissolved we add more water til we filled the flask to the line. After this we used to Dilution formula to figure out how much of the stock solution we needed to pour into the small flask. After we poured it into the small flask we filled it with water to the small flask line. In the end we had a diluted solution and a concentrated solution.

The one on the left is the diluted solution and the one on the right is the concentrated solution. For more information about diluted and concentrated solutions vist:  http://chemistry.tutorvista.com/physical-chemistry/dilute-solution.html?view=simple                             

Chemical Reactions

Unit 12: Chemical Reactions

 

This week in chemistry we learned all about chemical reactions including the different kinds of chemical reactions, how they happen, if they will happen, and how to balance the chemical equation to make them happen. Balancing a chemical reaction isn't as easy as it seems, it takes time and practice but with help from labs like the Nail Lab learning about chemical reactions and formulas became a lot easier. 

• Basic Things to Know About Reactions:  When you first start a reaction the materials you start with are called the reactants and the material(s) you end with are called the product(s). There are many symbols that go along with knowing how a chemical reaction takes place. Some of these symbols include (+) which means used to separate 2 reactants or 2 products, (an arrow) which means used for reversible reactions, and (aq) which means aqueous solution; the substance is dissolved in water.
• Diatomic Molecules: Diatomic molecules are specific elements that occur in nature in groups rather than separate. These elements include Br2, I2, N2, H2, O2, and F2. These elements are commonly known as the "heavenly 7".
• How to Balance a Chemical Equation: Balancing a chemical equation is not always the easiest thing but with practice it becomes much easier. The first thing to know when balancing the equation is that the equation had to have equal numbers of each element in the reactants an din the products. You must write the "skeleton equation" first then count the number of atoms on the reactant side and balance it on the product side. Remember never to change subscripts and balance of element at a time and you will do fine!
• How to Know a Chemical Reaction is Taking Place: There are 5 simple things you need to remember to know a chemical reaction is taking place. 1.) a temperature change (+q) means colder and (-q) means warmer, 2.) a color change, 3.) an odor, 4.) gas bubbles, 5.) a formation o f a solid (precipitate).

Types of Chemical Reactions

• Synthesis Reactions: A synthesis reaction is when 2 or more substances react to produce a single product. If two elements react then it is always a synthesis reaction. When there is a synthesis reaction remember there will be a single ionic product.
• Combustion Reaction: A combustion reaction is when an element or compound reacts with oxygen producing energy in the form of heat or light. O2 will always be a reactant and another reactant is typically hydrocarbon. Some but not all combustion reactions are also synthesis reactions. This picture is an example of a combustion reaction because its product results in heat and light.
• 
  Tips to balancing Combustion Reactions: 1.) Place a "2" in front of the hydrocarbon, 2.) balance the C on each side, 3.) go back and balance H, 4.) balance O2 last, 5.) simplify coefficients if you can. 
•  Decomposition Reactions: A decomposition reaction is when a single compound breaks down into 2 or more elements or compounds. It is also the opposite of a synthesis reaction.
• Single Replacement Reactions: A single replacement reaction is when one element switches places with another element in a compound. An example would be A + BX (arrow) AX + B.
• To know if one element will replace another we use the Activity Series chat. Activity decreases as you go down the row.

  
• Double Replacement Reactions: A double replacement reaction is an exchange of ion between 2 compounds. The cations will stay in place and the anions with switch places. This reaction usually takes place in aqueous solutions. A double replacement reaction will produce water, a solid, or a gas.
• We know a reaction will take place if it is soluble which means both reactants must be able to dissolve in water and dissociate into their ions. One product of the reaction must be insoluble.  

Nail Lab

 

When doing the nail lab we first mass out are reactants including the nail and copper chloride. After filling the beaker with the copper chloride and letting the nails sit in there for a few days we observed that copper was starting to form on the once clean nail. We know a chemical reaction took place because there was a color change of the copper chloride and a solid forming on the nail. We determined that the reaction was a single replacement reaction because one element switched places with another element in the compound. This nail lab helped me see and observe in depth what a real chemical reaction looked like. 

• Website: http://chemistry.about.com/od/chemicalreactions/a/reactiontypes.htm

IMF's and fun

This week in chemistry we learned about forces of attractions. Some of the forces included intramolecular forces, the attractive forces that hold atoms together within a molecule, and intermolecular forces, the attractive forces that hold identical molecules together between molecules. Also we learned about the three types of IMF's. The weakest IMF is called dispersion forces (AKA London forces). These type of forces are formed when two molecules become close and the e- cloud of one repel the other e-cloud. The second type of force is called dipole-dipole forces. These forces are formed when molecules orient themselves so the the slightly negative end of one molecule is attracted to the slightly positive end of the nearby molecule. The last and strongest bond is called a hydrogen bond. A hydrogen bond is formed when electronegetive atoms cause a large partial positive charge on the hydrogen atom. We also learned about phase changes. Phase changes require energy to happen. Phase changes that absorb energy make the particles move faster and the IMF's duplicate causing melting and evaporating. Phase change that remove energy make the particles move slower and strengthened the IMF's causing freezing and condensation. Lastly we learned about the phase diagram. The temperature and pressure shown on the graph determine the phase of a substance and have opposite effects. Higher temperature causes more liquid to evaporate but higher pressure causes vapor to condense.  

This week we also did multiple labs that related to what we learned this week. One lab we did was the drops on a penny. We took water first then ethanol and dropped as many drops on the head side of a penny as we could until the water/ethanol spilled over. By doing this lab we learned that water had a stronger intermolecule force because we could as more drops of water to the head of the penny than ethanol drops.  

Another lab we did was the CO2 bubble, which was the best lab. In this lab we mixed water and dry ice to create a gas, then we took a strip of cloth and soaked it in soapy water. After this we took the strip of cloth and ran it over the bowl containg the water and dry ice. After a few trys a bubble formed on the bowl causing the bubble to expand. We learned after that the attractrion that holds the molecules together of CO2  double bonds. 

Link:http://chemed.chem.purdue.edu/genchem/topicreview/bp/intermol/intermol.html#force

Electron configuration and flame test

    This week in science we learned about electron configurations and electrons in an atom. I found electron configuration very interesting yet easy. As we continued to learn and practice the rules they became easier and easier.

    While learning about electron configuration we learned many rules pertaining to orbitals. The first rule that we learned about orbitals Aufbau principle which stated that the lowest potential energy electron in an atom is found in the 1s sub level and electrons will occupy one orbital only after the previous orbital is completely full.  Next, we learned about Pauli exclusion principle telling us that if two electrons occupy the same orbital, they must have opposite spins. Lastly, we learned Hund's rule that says electrons will pair up in an orbital only when all orbitals in the same sub level have one electron. These rules were fairly easy to learn and made sense to me. Our lab for electron configuration was the flame test lab. In this lab we lit on fire various ions and observed the colors they created. After this experiment we learned that each ion had their own specific color and that this experiment would not be a useful way to detect an individual ion because the colors would mix to form a whole new color. As the picture shows Cu+ glows green when lit on fire. In this experiment as we lit more ions on fire I was surprised to learn all the ions had such varying, vibrant and pale, colors. From Ba+ pale yellow to Li+ hot pink. In this chapter I feel I understand the laws and rules of electron configuration very well. One thing I would be more interested in learning about though would be more of why scientists use the flame test. Including what they discover that has made a difference in our world today.