Thursday, November 4, 2010

Today we started class off by reviewing Lindsey's blog from the previous day. Her blog can be used as a reliable reference if you need help with the five different reaction types. Mr H also mentioned referencing packet pages 5 and 6 for pictures and definitions of the reaction types. As a review, the five reaction types are: synthesis, decomposition, combustion(REMEMBER O2!!!), single replacement, and double replacement. These reaction types were then used to determine the type of reaction on packet pages 7 and 8. The answers are as followed:
[page 7]
1. DECOMPOSITION
2. COMBUSTION/SYNTHESIS
3. SYNTHESIS
4. DECOMPOSITION
5. DECOMPOSITION
6. DOUBLE REPLACEMENT
7. SINGLE REPLACEMENT
8. SINGLE REPLACEMENT
9. SKIP!!!
10. DOUBLE REPLACEMENT\
[page 8]
11. DOUBLE REPLACEMENT
12. SKIP!!!
13. COMBUSTION
14. DECOMPOSITION
15. SINGLE REPLACEMENT
16. SINGLE REPLACEMENT
17. DOUBLE REPLACEMENT
18. DECOMPOSITION
19. COMBUSTION
20. SYNTHESIS
21. SINGLE REPLACEMENT

After determining type of reaction the chemical equations were, we moved on to the bottom of packet page 9. On this page, there were two questions giving the verbal chemical equation. Our task was to put the verbal chemical equation into symbols. Mr. H told us to find the reactants, find the products, and then balance equation. Problem number 31 states: Mercury(II) oxide decomposes into its elements. By using our knowledge from previous units, we were able to determine that the formula for mercury oxide is HgO, because they both have a charge of two which cancels out. Next, we knew that decomposes means that the two elements (Hg and O) would separate. Keeping Mr. H's UNCLE HONClBrIF in mind, specifically his cousin olive, we were able to determine that the oxygen would be O2 since all of Mr. H's uncle's children have two of arms, legs, noses, mouths, etc. Since the element oxygen was labeled O2, we would have to balance the equation out by putting a 2 in front of HgO and a 2 in front of Hg for the product. The final answer for question number 31 is: 2Hg0-->2Hg+02. The next problem (#32)follows the same criteria as #31. The problem states: Iron(II) oxide is synthesized from its elements. The reactants would both be the separated elements, because the equation is synthesized. With cousin Olive in mind again, the reactants would be Fe+O2 with products of FeO. Because there is two O elements to begin with, you would make the FeO into 2FeO. With changing the product, you would also have to change the reactant Fe to 2Fe. This makes the final answer: 2Fe+O2-->2FeO.

After these brief packet pages, we worked on the rest of our Classifying Chemical Reactions Lab (CR1). We were able to finish the eight reactions and afterwards, we shortly discussed the reactants and products for each station.
They were:
Reaction #1 R: Mg2 and O2 (synthesis)
Reaction #2 R: 2HCl and 2Mg P:H2 and 2MgCl (single replacement)
Reaction #3 R:NH4CO3 (decomposition)
Reaction #4 R: CaCO3 and 2HCl P: CaCl2 and CO2 and H2O (decomposition)
Reaction #5 R:CuCl2 and Zn P:ZnCl2 and Cu (single replacement)
Reaction #6 R:CuCl2 and Na3PO4 P:NaCl and Cu3(PO4)2 (double replacement)
Reaction #7 R:NaHO and HCl P:NaCl and H2O (double replacement)
Reaction #8 (my group didn't get there yet)

This concluded our day!
HOMEWORK:
due friday--4.2 Reading sheet W.A.\
due monday--Web Assign (one in class)
due tuesday--Web Assign
due wednesday--web assign and test prep

Wednesday, November 3, 2010

Today we went straight to the Math Computer Lab to work on our web assigns. To do one of the web assigns you needed to know how to balance equations and classify reactions. If you are still having trouble balancing equations then you should look at past blogs, textbook pages 60-61, and packet pages 1-4. Classifying reactions was a newer concept that I’m going to explain.

Synthesis:

· A + B = AB

· Formation of more complex compounds from simpler compounds

· Formation of compounds from its elements

Decomposition:

· AB = A + B

· Breaking down of more complex compounds into simpler compounds

· Opposite of synthesis

Combustion:

· REMEMBER O2

· Involve reaction of a substance with oxygen gas (O2)

· Some combustion reactions are also synthesis

Single Replacement

· Metal: A + BC = AC + A

· Non-metal: A + BC = BA + C

· If there is one element by itself on either side

· Replaces one of the ions in the compound

Double Replacement:

· AB + CD = AD + BC

· Compounds on both sides

· Precipitation Reaction and acid-base neutralization reactions

All this information and more can be found in packet pages 5-6. If you need additional information you can visit this site:

http://misterguch.brinkster.net/6typesofchemicalrxn.html

Today's chemistry class was very busy! We started class immeadiatly following the bell when Mr.H told us to copy down the title and purpose of the first lab of Unit 4, Classifying Chemical Reactions Lab. This can be found on page 17 of your Unit 4 Packet. We then put that away and took a look at Tammy's blog from yesterday. Mr.H was very impressed by it, and said that it was a good resource.

Then, we got into our packet work. Mr.H reminded us that we should have read pages 5 and 6, because that is what we would be learning today. Pages 5 and 6 were about the types of reactions. The different types are:

Synthesis-remember 2 reactants -> 1 product ex. 2 H2 + O2 -> 2H2O

Decomposition-remember 1 reactant -> 2 products ex. 2 H2O -> 2 H2 + O2

Combustion-remember ALWAYS includes oxygen(O2) ex. CH4 + O2 -> CO2 + 2 H2O

Single Replacement-remember 1 element gets replaced ex. 2 Al + 3 CuCl -> 3 Cu + 2 AlCl

Double Replacement-remember 2 elements switch places ex. HCl + NaOH -> NaCl + H2O

**for more details and great pictures, go to pages 5 and 6 in your packet.

After going over the types of reactions, we did pages 3 and 4 in the packet. While doing those problems we were also told to classify the reactions. The answers are as follows:
1. 2 CU + S -> Cu2S Synthesis
2. Na2O + H2O -> 2 NaOH (no classified reaction)
3. 2 Na + 2 H2O -> 2 NaOH + H2 Single Replacement
4. 4 Na + O2 -> 2 Na2O Combustion
5. Ba(OH)2 +CO2 -> BaCO3 + H2O (already balanced, no classified reaction)
6. 3 Ca(OH)2 + 2 H3PO4 -> Ca3(PO4)2 + 6 H2O Double Replacement
7. 2 Al + 3 ZnCl2 -> 2 AlCl3 + 3 Zn Single Replacement
8. 2 Al(OH)3 -> Al2O3 + 3 H2O Decompostion
9. 3 Ti + 2 N2 -> Ti3N4 Synthesis
10. Fe2O3 + 3 CO -> 2 Fe + 3 CO2 (No classified reaction)
(END OF PAGE 3)
11. P2O5 + 3 H2O -> 2 H3PO4
12. FeS + 2 HCl -> FeCl2 +H2S
13. Cl2 + 2 LiI -> 2 LiCl + I2
14. Hg + O2 -> 2 HgO

Some helpful hints Mr.H gave us were that not every single reaction needs to be classified, and that you should first write the chemical reaction formula out, and THEN balance it.

Before we got into the lab, Mr.H told us about his Uncle Honclbrf and his children, his uncle named his children; Harry, Oliver, Nana, Clara, Brady, Isabelle, and Fred. He also said that they were weird because they had to of every single body part, 2 legs, 2 eyes, 2 noses, to mouths, ect.
Then Mr.H showed us this:

H2O2N2Cl2Br2I2F2

This was Mr.H's clever way of telling us that the elements Hydrogen(H), Oxygen(O),

Nitrogen(N), Chlorine(Cl), Bromine(Br), Iodine(I) and Fluorine(F) always have a subscript of 2 when they stand alone in a chemical equation. This is very important to remember!!!

Finally, we got into our lab groups and began lab CR1. We did not finish becuase the lab is long, but we will resume this lab on Thursday, not Wednesday, and finish it then.

Homework: Webassign due Wednesday, Novemeber 3

Monday, November 1

We started class today by turning in our homework from the Chemthink assignment. We reviewed what we learned on Friday about chemical reactions. Here are some facts about chemical reactions:

• Always rearrangement of atoms



• Breaks bonds and forms new bonds



• Reactants (starting materials) turned into products (ending materials)



• Conservation of mass (atoms are neither created nor destroyed)



• Conservation of charge (protons and electrons are neither created nor destroyed)



• Represented symbollically by chemical equations

We then practiced what we learned by doing page 1 in the unit packet.

Question 1 involved writing the formula of reactants and products based on a picture. We talked about turning the visual into words, so it would be 1 molecule of methane gas reacts with 2 molecules of oxygen to create 1 molecule of carbon dioxide and 2 molecules of water. We then were able to write the formula for that. The arrow between the reactants and products represent that the reactants turned into the product. In question 2, we had to use our unit 1 skills to count the number of atoms in different chemical reaction formulas. The numbers should be equal in both sides of the equation, which means that the atoms were conserved. For questions 3 and 4 we had to count the number of each atom on the reactant and product side of a given equation. If there are the same number of atoms on both sides, that means it is a balanced equation.

We then learned about balancing chemical equations. Here are some important things to remember while balancing a chemical equation.

• Add coefficients in front of formulas. (Do NOT change formulas' subscripts and supersubscripts)


• Trial and error process

- do one element at a time; pick the element that is present in one location on reactant and product side

- use whole number coefficients; if a coefficient comes out to be a half number, double them all

We practiced balancing equations by doing page 2 in the packet.

With question 5, we started with balancing N. Since there were 2 N molecules on left, but only 1 on the right, we added a coefficient of 2 in front of NH3 on the product side. That caused there to be 6 H molecules on the product side. We added the coefficient 3 in front of H2 so that there would also be 6 molecules of H on the reactant side. The balanced equation was now N2+3H2 ---> 2NH3. To make sure this is correct, you could count the number of each atom on each side and make sure they are equal. Mr. H reminded us to make sure that when balancing equations, you always want the lowest possible set of whole numbers.

We were assigned our homework, which is to read page 5-6 in the packet and 60-61 in the textbook. These are about classifying reactions.

We ended class with a demonstration of the solid zinc reacting with the aqueaous hydrochloric acid. This created hydrogen gas and zinc chloride. The chemcial formula for it looked like this:

Zn(s)+2HCl (aq) ---> H2 (g) + ZnCl2 (aq)

The signs that this was a chemical reaction were that a gas formed and the test tube was warm.

Here is a video of the reaction of zinc with hydorchloric acid.

http://www.youtube.com/watch?v=CfrsElKZaLU&feature=related

Friday, October 29

This Friday we got our Unit 3 tests and our first quarter grades. We went over the test and then Mr. Henderson explained to us that the computer took off three of our worst webassign homework grades. There seemed to have been a problem, so he said that he would fix it once we went to the science computer lab. Once we got into the science computer lab we had to get with our qroups and exchange our information and work for the flight crash problems. Mr. Henderson said that if groups finished early they could start on the homework which was a Chemthink on chemical reactions. First we had to look at the tutorial to get the idea of the subject. Then we had to take a quiz on the material we just learned. You could only get 2 wrong. If you got three wrong you had to start over. mr. Henderson also told us a bout a work sheet on the back of the new packet that would be due with the Chemthink. The page has a front and a back side to it. An easy way to get it done would be, going through the tutorial and writing in the answers as you follow.

The basics of what we will be learning about in this unit is that the starting materials are called reactants, the materials that are created are called the products. You know that there has been a change when there is an arrow in between the two. This is just a little from the chemthink. There is a lot more to it than this. But I will let you figure that out for yourself.