Introduction to Moles

January 25, 2011

We began class by stamping our homework, the Mole Lab, and reviewing pages 7 and 8.
(Review)
- a compound is ionic if it contains a metal such as NaNO3, and is simply named sodium nitrate
- if the metal is a transition metal, the compound includes roman numerals, such as Fe3N2, which is named iron (II) nitride
- a compound is covalent if it contains two nonmetals such as PCl5, which includes a prefix, in this case, phosphorus pentachloride

- to calculate the molar mass of a compound, first write the compound's formula. Then take the number of atoms of the first element and multiply it by the element's atomic mass, found on the periodic table. Continue to do this with each element, and add up the masses of each element at the end. For example,
carbon dioxide --- CO2
(one carbon atom, 1 x 12.01 (the atomic mass of carbon)) + (2 x 16.00) = 44.01 g
44.01 g is the molar mass of carbon dioxide (for each mole of CO2 there is 44.01 g)

To calculate the number of moles of 50g of carbon dioxide, use the multiplication method that I can't remember the name of. It involves canceling out units of measurement by putting them diagonally across from eachother ------ x ------- (< like that)

SO...
begin the equation with 50 g of CO2.
50g x 1 mole/44.01 g --- grams cancel out, so you are left to divide 50 by 44.01, to get the answer 1.14 mol CO2

Pages 1 and 2 just went into more depth with the multiplication method with the name I can't remember.
Here's an example problem: What is the mass of 3.57 x 10^-4 mol of N2O5?
start off with what the problem gives you-
3.57 x 10 ^-4 mol N2O5 x 108.02* g/ 1 mol -- mol cancels out, leaving you to multiply 3.57 x 10^-4 by 108.0 to get .0386 g N2O5 (you might want to round that)

*you get 108.02 (the molar mass of N2O5) by (2 x 14.01) + (5 x 16.00)

Thats basically it. The homework was to finish pages 1 and 2.

Chain Reactions and Review

January 14, 2011

Dear Period 8,

On Friday we went over Chain Reactions and Nuclear Reactors.We also received the 1st semester review packet. Webassigns are extra credit and The Test is on Monday January 10, 2011.

Notes: The atomic # determines the type of element. Isotopes is the term used to describe an element written in this format. Uraniium has an unstable nucleus, so it is always found decaying. The atoms that it is found with are atoms it has transmuted into.

Link to Alpha, Beta, and Gamma review: http://gbs-moodle.glenbrook225.org/moodle/mod/resource/view.php?id=652

Chain Reactions:

Examples: Uranium-239

Mass: 239

Atomic Numbef: 92

Event 1-2-3-4-5-6-7
# of Reactions 1-2-4-8-16-32-64

Nuclear Reactors:

Control rods- absorb neutron to slow down a chain reaction

Fuel rods- contain 3% of U-235

Moderator- Slows down neutrons, so control rods can absorb them.

Fission- Splitting of atoms for energy

Fusion- Combining atoms to release energy ex. sunstars

The answers to the review guide: http://http://gbs-moodle.glenbrook225.org/moodle/mod/resource/view.php?id=666

Homework: Finish review guide, Webassigns extra credit, and study for Quest

Anson. V

Jan. 4 2011

Today Mandarino stamped pg. 3 for homework. the homework for today was pg. 9 and #3 on pg. 10. we learned about radioactive decay as well as aplpha and beta particles(also waves). we learned that isotopes are atoms with the same protons but different neutrons. we learned half-lives were the time period it takes for a substance undergoing decay to decrease by half.

December 14- Double Replacement Lab

Today in class we mainly reviewed our results from the double replacement lab that we did yesterday(Monday the 13th). The equations from the lab are as follows: If you still have any questions about balancing equations than you should either talk to Mrs. M or go to the TLC because we will be having our quest about Balancing equations this Thursday(December 16th).

Today we were also given back our partner quizzes, in which we were informed that we didn't do to well on, so tonight for homework we have to correct them. If you were absent or still haven't taken the partner quiz then you can get it straight off the moodle. The answer key to the quiz will be posted later.

DON'T FORGET: Our chemthink and webassign are both due at 11:59 tomorrow night.

Study for our upcoming quest!

Chandler F.

Scribe Post: Thursday, November 9, 2010

Hello,
Today in class, everybody present collected an Activity Series sheet, which basically showed which metals and nonmetals were more/ less active.  Next, we read the lovely scribe post from last night.  After that, Mrs. M made a quick announcement.  She told us that she would not be in class tomorrow, that page twenty is our homework, we have a partner quiz tomorrow, and to be ready for a quiz monday, a quest next thursday, and a CSI/ Winter Break party next friday.  She also told us that we will be reviewing as well as starting the next chapter on both tuesday, and wednesday.  Afrer that, Mrs. M stamped, and reviewed page eighteen (last nights homework).  Page eighteen was about balancing equations.  When balancing, equations, it is essential to make sure you balance the equation.  How do I do that? You must be asking yourself right now.  Well, when balancing an equation, you must make sure to see that all the elements in the reactants and products are equal, like a teeter-toter.  Lastly, we did page nineteen, which was about predicting products.  You do this by seeing what kind of a reaction it is, depending on wheter it is a synthesis, decomposition, single replacement, double replacement, or combustion. 

Thats all folks.

Reactant Types

Today in class, we went over the homework from last night. Then, we talked about reactant types. There are five different types of reactants:

Shown using variables:

1. Synthesis(combination)= A+B ->AB

2. Decomposition= AB ->A+B

3. Single Replacement= A+BC->B+AC

**A must be more reactive than the element it is replacing (In this case it is B).

4. Double Replacement= AB+CD->AD+BC

5. Combustion= C6H12+O->6CO2+6H2O

** Combustion works with hydrocarbons. It will ALWAYS produce CO2+H2O.

Shown using formulas:

1. Synthesis: 2Mg+O2->2MgO

2. Decomposition: 2H2O->2H2+O2

3. Single Replacement: Cu+2AgNO3->2Ag+Cu(NO3)2

** If the element is less reactive than the element it is replacing, there will be no reaction.

4. Double Replacement: Pb(NO3)2+K2S->PbS+2KNO3

5. Combustion: C4H10+6.5O2->4CO2+5H20

Homework tonight is page 18. Don't forget!

Polarity

Polarity is a theory in chemistry that tries to explain the unequal sharing or sharing of electrons. These types of sharing electrons define what type of bond a substance is. The bonds are either polar, meaning that the substance has an unequal sharing of electrons, like water, or if it is non-polar, meaning the substance has an almost uniform electric balance, like methane. Also, polarity can also affect the physical characteristics of a substance like melting point, boiling point, freezing point, etc.
The pull between the elements is considered electro negativity, and it is measured and justified by the formation of an electric dipole. What a dipole is is a separation of positive and negative charges into two poles. Furthermore, whichever element has more pull is deemed delta negative, represented by the greek symbol for delta, also with a negative sign. The one with the least pull is deemed delta positive.

Alec W.